RU2520426C1 - Method and scheme for threshold voltage loss reduction and stabilisation of mos transistors at ic - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: device includes a source of reverse bias for MOS transistors substrate in regard to their sources that generates stabilised reverse-bias voltage, which increases with decrease of threshold voltage of the MOS transistor sensor with the source short-circuited to the substrate. The device includes a charge pump device that generates pulsating voltage with absolute value bigger than absolute value of the substrate reverse-bias voltage, a threshold voltage sensor for the MOS transistors, an operating amplifier, and a resistance divider.

EFFECT: decrease of loss current and stabilisation of threshold voltage for submicron MOS transistors with low threshold voltage values at MOS IC.

6 cl, 6 dwg, 1 tbl

Description

The group of inventions relates to electronics and can be used in submicron MOS integrated circuits (ICs) of signal processing.

Modern submicron CMOS IC technologies are characterized by lower threshold voltages and increased drain-source leakage. The leakage problem is exacerbated by the spread of threshold voltages of MOS transistors (Vth) due to deviation of the process parameters in the manufacture of ICs, as well as drift of threshold voltages during the operation of ICs with temperature changes and influences leading to charge generation in the oxide. Higher threshold voltage values lead to lower circuit speed, and lower thresholds lead to higher drain-source leaks. For analog ICs, the spread of threshold voltages and their change during operation can lead to degradation of accuracy parameters and disturbances in the functioning of the IC long before the leakage current problem appears, therefore, one of the most important ways to increase the reliability of analog circuits is to stabilize threshold voltages, i.e., compensate for the technological spread and threshold voltage drift during IP operation.

The purpose of the invention is to reduce the leakage current of the drain-source of submicron MOS transistors, as well as the stabilization of threshold voltages in the MOS IC.

It is known that the reverse bias of the substrate relative to the sources increases the threshold voltage of MOS transistors and, thereby, reduces the drain-source leakage current, see, for example, S. Zi, Physics of Semiconductor Devices, Moscow, Mir, 1984. , vol. 2, pp. 18-19. The reverse bias of the substrate also reduces the drain-source leakage current of MOS transistors in the subthreshold region, drastically reducing the so-called characteristic gate-source voltage S, which is required to reduce the drain-source leakage current in the subthreshold region by an order of magnitude (S. Zi “Physics of Semiconductor Devices”, Moscow, Mir Publishing House, 1984, v. 2, p. 23).

Known circuits that form a reverse bias of the substrate to reduce the leakage current of MOS transistors in the IC, for example, the circuit according to US patents US 4401897, US 4581546, US 5909140, US 7504876B1, US 7746160B1 and application US 20080191791, A1.

The basis of all these schemes is a charge pump that generates a pulsating voltage, either higher than the voltage of the power source for the n-substrate of p-channel MOS transistors, or lower than the voltage of the common bus (ground) for the p-substrate of n-channel MOS transistors. This ripple voltage is applied to the substrate, forming its reverse bias relative to the sources of MOS transistors. Usually this bias is used in the passive (stby) mode of the IC to reduce the current consumption due to transistor leaks, while the pulsating nature of the bias voltage of the substrate is uncritical. However, the ripple bias voltage of the substrate in the active mode of the IC can cause problems, especially in analog ICs, which are critical to interference from the ripple voltage of the substrate.

Closest to the claimed is a source of reverse bias of the substrate according to US patent "Substrate Bias Feedback Scheme to Reduce Chip Leakage Power" No. 8085085B1, M. Cl. G05F 1/10, pr. 06.28.2010, publ. 12/27/2011, presented in Figure 1. A known source of reverse bias of the substrate includes a charge pump 100, which generates a pulsating bias voltage of the substrate of the MOS transistors Vsub 140, and two operational amplifiers (op-amps) 110 and 120. The first op-amp 110 together with the transistor 115 and the resistor Rbias 116 forms a reference current , the value of which is determined by the reference voltage Vref 103 and the resistor Rbias 116. The current of the transistor 112, proportional to the reference current, is compared with the leakage current of the drain-source of the reference n-channel MOS transistor 113, shorted to the source and the common terminal 104 shutter. If the leakage current of the transistor 113 is greater than the current of the transistor 112, then the voltage at the inverting input of the second op-amp 120 decreases and becomes lower than the voltage Vpwr 105 set at the non-inverting input. The output voltage of the op-amp 120 increases, causing an increase in the absolute value of the negative output voltage Vsub 140 of the pump device. Thus, the op-amp 120 regulates the output voltage of the charge pump, providing an averaged leakage current of the reference MOS transistor at the current level set by the transistor 112.

The described reverse bias source can be used both in the passive and in the active mode, reducing the influence of the leakage current on the parameters of the IC with variations in the process technology, temperature, and supply voltage (in the literature on these conditions: process - P, voltage - V, temperature - T are denoted by "PVT"). However, this source has the aforementioned drawback associated with the pulsating nature of the reverse bias voltage generated by the charge pump, which makes it unacceptable in analog circuits. The disadvantage of this source of reverse bias is the inability to adequately compensate for the technological variation of the threshold voltage and its drift caused by operating conditions. The latter is due to the fact that the current comparator that activates the charge pump is a threshold device configured for one specific value of the leakage current of the MOS transistor-sensor with a gate shorted to the source, and cannot adequately respond to changes in the leakage current in the subthreshold region with an exponential dependence on voltage shutter source. The third drawback is due to the presence of severe restrictions on the maximum voltage of the drain-substrate of MOS transistors. Obviously, the maximum value of the ripple voltage of the reverse bias of the substrate should not exceed the difference between the maximum voltage of the drain-substrate and the maximum supply voltage. In this case, the minimum value of the ripple voltage of the reverse bias may not be sufficient to achieve the goal of eliminating leaks, taking into account the dependence of the charge pump efficiency on PVT. In addition, to prevent possible failure of the IC due to exceeding the maximum voltage of the drain-substrate of MOS transistors with reverse bias on the substrate, an additional reverse bias voltage limiting device is used in the well-known reverse bias source, which leads to the complication and increase of the source current consumption (by 1, a level limiting device is not shown for simplicity).

The aim of the invention is to reduce the leakage current drain-source and the stabilization of the threshold voltage of the MOS transistors in the MOS IC.

The goals are achieved in that in a method of reducing drain-source leakage and stabilizing threshold voltages of MOS transistors in an IC, including generating a ripple voltage by the charge pumping device and generating a reverse bias voltage of the MOS transistors, a ripple output voltage of the charge pump device with an absolute value greater than the absolute the values of the reverse bias voltage of the MOS transistor substrate are converted to a stabilized reverse bias voltage of the MOS transistor substrate tori, increasing with decreasing threshold voltage of the MOS transistor-sensor.

The goals are also achieved by the fact that in the circuit to reduce drain-source leakage and stabilize threshold voltages of MOS transistors in an IC, including a source of reverse bias of the substrate relative to the sources, containing a charge pump device and an operational amplifier, the charge pump device generates a pulsating voltage with an absolute value of a larger absolute the reverse bias voltage of the substrate, the non-inverting input of the operational amplifier is connected to the output of the threshold voltage sensor MOS transistor s, inverting the input to the output of the resistive divider connected between the terminals of the reference voltage and the output of the amplifier, and the output of the amplifier forms the output of a reverse bias voltage source and is connected to the substrate of the MOS transistors, and the output stage of the operational amplifier is powered from the output of the charge pump.

In a particular case, in the circuit to reduce drain-source leakage and stabilize threshold voltages of n-channel MOS transistors, the goals are achieved in that the charge pump device generates a pulsating negative voltage with an absolute value greater than the absolute value of the reverse bias voltage of the substrate, a non-inverting input of the operational amplifier is connected to the output of the threshold voltage sensor of n-channel MOS transistors, an inverting input to the output of a resistive divider connected between the terminals of the reference voltage and output of the amplifier, and the output of the amplifier forms the output of a negative bias voltage source and is connected to the p-substrate of n-channel MOS transistors, the source and substrate of the n-channel MOS transistor of the output stage of the operational amplifier connected to the output of the charge pump.

In a particular case, in the circuit to reduce drain-source leakage and stabilize threshold voltages of p-channel MOS transistors, the goals are achieved by the fact that the charge pump device generates a pulsating voltage with a value greater than the sum of the supply voltages and the positive bias of the n-substrate, the non-inverting input of the operational amplifier is connected to the output of the threshold voltage sensor of p-channel MOS transistors, the inverting input to the output of the resistive divider connected between the terminals of the ground and the output of the amplifier, and the output the amplifier forms the output of a positive bias voltage source and is connected to the n-substrate of the p-channel MOS transistors, the source and substrate of the p-channel MOS transistor of the output stage of the operational amplifier connected to the output of the charge pump.

In a particular case, in the circuit to reduce drain-source leakage and stabilize threshold voltages of n-channel MOS transistors, the goals are achieved in that the threshold voltage sensor of n-channel MOS transistors includes a current-sensing resistor connected between the reference voltage output and the drain of the n-channel MOS transistor, the source of which is connected to its substrate and the earth outlet, and the gate connected to the drain forms the output of the sensor, and the ratio of the current specified by the current-setting resistor and the slope of the MOS transistor-sensor and determines the steepness of the dependence of the reverse bias of the substrate on the threshold voltage.

In a particular case, in the circuit to reduce drain-source leakage and stabilize threshold voltages of p-channel MOS transistors, the goals are achieved in that the threshold voltage sensor of r-channel MOS transistors includes a current-sensing resistor connected between the ground terminal and the drain of the p-channel MOS transistor, the source , which is connected to its substrate and the power output, and the gate connected to the drain forms the output of the sensor, and the ratio of the current set by the current-setting resistor and the slope of the MOS transistor-sensor is determined t the steepness of the dependence of the reverse bias of the substrate on the threshold voltage.

The goal of reducing the leakage current of the drain-source of MOS transistors in the inventive method and circuits is achieved by reverse biasing the substrate of MOS transistors relative to their sources. The effect of reducing the leakage current is achieved, both by increasing the threshold voltage in proportion to the square root of the reverse bias voltage (see, for example, S. Zi, “Physics of Semiconductor Devices,” Moscow, Mir Publishing House, 1984, vol. 2 , pp. 18-19), and by reducing the characteristic gate-source voltage S, required to reduce the drain-source leakage current by an order of magnitude in the subthreshold region (S. Z. “Physics of Semiconductor Devices”, Moscow, Mir ", 1984, v. 2, p. 23). It is known that the reverse bias of the substrate of MOS transistors increases the threshold voltage of MOS transistors the more, the thicker the gate dielectric and the higher the concentration of impurities in the substrate, therefore, reverse bias of the substrate even more effectively eliminates leakage through spurious channels under a thick dielectric, which can occur, for example, in the result of exposure to operational factors generating a charge in the oxide. Unlike the known ones, in the inventive method and circuit, the reverse bias voltage of the substrate is not pulse, but stabilized, which makes it possible to use them in analog ICs without sacrificing accuracy parameters.

The goal of stabilization of threshold voltages is achieved by the fact that in the claimed schemes the source of reverse bias of the substrate generates a reverse bias voltage that increases with decreasing threshold voltage of the MOS transistor with a source shorted to the substrate, emitted by the MOS transistor-sensor. In this case, the threshold voltage of the MOS transistor-sensor corresponds to the technological angle of the manufacturing process (the values of the gate dielectric thickness, impurity concentration in the substrate, etc. obtained during the manufacturing process) and depends on the current operating conditions and external influences (for example, decreases with increasing temperature, changes when the charge in the oxide changes). Thus, if, for some technological or operational reasons, the effective threshold voltage of the MOS transistor-sensor decreases or increases relative to the set value, the reverse bias voltage will increase or decrease accordingly, thereby reducing the magnitude of the change in the effective threshold voltage of MOS transistors with reverse bias by the substrate.

The invention is illustrated by drawings.

Figure 1 presents a diagram of reducing the leakage current of the drain-source of MOS transistors in an IC with a well-known prototype source of reverse bias of the substrate of MOS transistors.

Figure 2 presents a diagram of the reduction of leakage current drain-source and stabilization of the threshold voltage of the MOS transistors in the IC with the claimed source of reverse bias of the substrate of the MOS transistors according to claims 1 and 2 of the Formula.

Figure 3 presents a diagram of reducing the drain-source leakage current and stabilizing the threshold voltages of n-channel MOS transistors in ICs with the claimed source of reverse bias of the p-substrate and the threshold voltage sensor of n-channel MOS transistors according to claims 3 and 4 of the Formula.

Figure 4 presents a diagram of reducing the drain-drain leakage current and stabilizing the threshold voltages of the p-channel MOS transistors in the IC with the claimed source of reverse bias of the n-substrate and the threshold voltage sensor of the p-channel MOS transistors according to claims 5 and 6 of the Formula.

Figure 5 transistors in the IP presents the connection diagram of the operational amplifier in the inventive sources of reverse bias of the substrate according to claims 3 and 5 of the Formula.

Below, by the example of the drawings, a description is given of the device and operation of the inventive circuits of sources of reverse bias of the substrate of MOS transistors.

Figure 2 presents a diagram of reducing the leakage current of the drain-source and stabilization of the threshold voltage of the MOS transistors with the claimed source of reverse bias of the substrate of the MOS transistors relative to the sources according to claims 1 and 2 of the Formula. The reverse bias source circuit includes a charge pump 100, which generates at its output 201 a voltage pulsating with the frequency of the input clock frequency 102 (Fclk) with an absolute value greater than the absolute value of the required reverse bias voltage of the substrate and supplied to the output stage of the operational amplifier 210. Non-inverting input 212 the amplifier 210 is connected to the output of the threshold voltage sensor of the MOS transistors 260, the inverting input 211 to the output of the resistive divider from the resistors 220 (R1) and 230 (R2) connected between the output E 250 and the reference voltage output of the amplifier 240. The output amplifier 240 is also the output of the reverse bias voltage source and connected to the substrate of MOS transistors, the leakage current which requires reduced.

Figure 3 presents a diagram of reducing the drain-drain leakage current and stabilization of threshold voltages of n-channel MOS transistors with the p-substrate reverse bias source and threshold voltage sensor of n-channel MOS transistors claimed in claims 3 and 4 of the Formula. The above reverse bias source circuit includes a charge pump 100, which generates a negative voltage pulsating with an input clock frequency 102 (Fclk) at its output 301, with an absolute value greater than the absolute value of the required reverse bias voltage of the p-substrate and supplied to the output stage of the operational amplifier 310 The non-inverting input 212 of the amplifier 310 is connected to the output of the threshold voltage sensor of the n-channel MOS transistors 360, the inverting input 211 to the output of the resistive divider from the resistor ov 220 (R1) and 230 (R2), connected between the terminals of the reference voltage 350 and the output of the amplifier 340. The output 340 of the amplifier is also the output of a negative bias voltage source (-Vpbulk) and connected to the p-substrate of n-channel MOS transistors, current leaks to be reduced. The threshold voltage sensor of n-channel MOS transistors 360 in accordance with claim 3 of the Formula includes a current-sensing resistor 370 connected between the output of the reference voltage 350 and the drain of the n-channel MOS transistor 380, the source of which is connected to its substrate and the earth terminal 390, and the gate connected to the drain, forms the output of the sensor, and the ratio of the current specified by the current-setting resistor and the slope of the MOS transistor-sensor 380 determines the slope of the dependence of the reverse bias of the substrate on the threshold voltage.

Figure 4 presents a diagram of reducing the drain-drain leakage current and stabilization of threshold voltages of p-channel MOS transistors with the reverse bias source of the n-substrate and the threshold voltage sensor of p-channel MOS transistors as claimed in paragraphs 5 and 6 of the Formula. The above reverse bias source circuit includes a charge pump 100, which generates a positive voltage pulsating with an input clock frequency 102 (Fclk) at its output 401, which is greater than the sum of the supply voltage and the required positive bias voltage of the n-substrate and supplied to the output stage of the operational amplifier 410. The non-inverting input 212 of the amplifier 410 is connected to the output of the threshold voltage sensor of the p-channel MOS transistors 460, the inverting input 211 to the output of the resistive divider from the resistors 220 (R1) and 230 (R2) connected between the terminals of the earth 490 and the output of the amplifier 440. The output 440 of the amplifier is also the output of a reverse bias voltage source (Vnbulk) and is connected to the n-substrate of p-channel MOS transistors whose leakage current needs to be reduced. The threshold voltage sensor of p-channel MOS transistors 460 in accordance with claim 5 of the Formula includes a current-sensing resistor 470 connected between the ground terminal 490 and the drain of the p-channel MOS transistor 480, the source of which is connected to its substrate and the power terminal 450, and the gate connected with the drain, forms the output of the sensor, and the ratio of the current specified by the pick-up resistor and the slope of the MOS transistor-sensor 480 determines the slope of the dependence of the reverse bias of the substrate on the threshold voltage.

Figure 5 presents the connection diagram of the operational amplifier in the inventive sources of reverse bias of the substrate according to claims 3 and 5 of the Formula. On figa presents a connection diagram of an operational amplifier in the claimed source according to claim 3 of the Formula of the reverse (negative) bias of the p-substrate of n-channel MOS transistors. The input stage 510 of the amplifier with non-inverting 212 and inverting 211 inputs is connected to the terminals of the supply voltage 350 and ground 390. The output stage of the amplifier consists of a complementary pair of n- and p-channel MOS transistors 5 13 and 5 14 controlled by the outputs of the input stage, the combined drains of which form an output of an amplifier 340 connected to a biased p-substrate of n-channel MOS transistors. The source and substrate of the output p-channel transistor are connected to the output of the supply voltage 350, and the source and substrate of the output n-channel transistor are connected to the output of the charge pump 301 with a pulsating negative voltage, the absolute value of which is greater than the absolute value of the required offset of the p-substrate. At the same time, a stabilized negative voltage (-Vpbulk) of the reverse bias of the p-substrate of the required value and with a significantly reduced ripple is formed at the amplifier output.

On figb presents a connection diagram of an operational amplifier in the claimed source according to claim 5 of the Formula of the reverse (positive) bias of the n-substrate of p-channel MOS transistors. The input stage 510 of the amplifier with non-inverting 212 and inverting 211 inputs is connected to the terminals of the supply voltage 450 and ground 490. The output stage of the amplifier consists of an output stage controlled by a complementary pair of n- and p-channel MOS transistors 515 and 516, the combined drains of which form the output of the amplifier 440, connected to a biased n-substrate of p-channel MOS transistors. The source and substrate of the output n-channel transistor are connected to the ground terminal 490, and the source and substrate of the output p-channel transistor are connected to the output of the charge pump 401 with a pulsating positive voltage greater than the sum of the supply voltage and the required positive bias voltage of the n-substrate. At the same time, a stabilized positive voltage (Vnbulk) of the reverse bias of the n-substrate of the required magnitude and with a significantly reduced ripple is formed at the amplifier output.

Consider the work of the claimed formula 3 and 4 of the Formula for reducing the leakage current of the drain-source of n-channel MOS transistors with a source of reverse bias of the p-substrate and the threshold voltage sensor of n-channel MOS transistors shown in FIG. 3. The charge pump 100 generates at its output 301 a negative voltage pulsating with the frequency of the input clock frequency 102 (Fclk) with an absolute value greater than the absolute value of the required reverse bias voltage of the p-substrate. The pulsating nature and the absolute value of the output voltage of the charge pump do not allow it to be directly fed to the substrate of n-channel MOS transistors in analog ICs due to its effect on the parameters through stray capacitances of the drain-substrate, channel-substrate and gate-substrate, and also due to excess allowable voltage drain-substrate n-channel MOS transistors. Note that the voltage of the gate-substrate is not critical, since when the voltage at the gate of the n-channel MOS transistor is higher than the threshold, the gate is shielded from the substrate by the channel region and the depletion layer of the p-n junction between the n-channel and the p-substrate. The operational amplifier 310 in an inverting switch performs the function of generating, at its output 340, a stabilized negative reverse bias voltage of the p-substrate of n-channel MOS transistors, with an absolute value increasing with decreasing threshold voltage of the n-channel MOS transistor with a source shorted to the substrate. To perform this function, the non-inverting input 212 of the amplifier 210 is connected to the output of the threshold voltage sensor of the n-channel MOS transistors 360, the inverting input 211 to the output of the resistive divider from the resistors 220 (R1) and 230 (R2) connected between the terminals of the reference voltage 350 and the output of the amplifier 340. The output 340 of the amplifier is the output of a reverse bias voltage source and is connected to the p-substrate of n-channel MOS transistors, the leakage current of which must be reduced.

The threshold voltage sensor of n-channel MOS transistors 360 in accordance with claim 3 generates a voltage Vgsn at its output equal to the gate-source voltage of transistor 380 at a current determined by formulas (1) and (2)

,

,

where Idsn is the drain current of the MOS transistor-sensor, specified by the resistance of the current-setting resistor Rt, from the reference voltage source Vref;

Kn is the slope of the n-channel MOS transistor-sensor;

Vthn is the threshold voltage of the n-channel MOSFET sensor.

It can be seen from (1) that the output voltage of the sensor Vgsn generally depends on the threshold voltage Vthn and the slope Kn of the MOS transistor. However, by decreasing the sensor current Idsn given by the resistance of the current-sensing resistor Rt and increasing the slope Kn, we can almost eliminate the influence of the slope Kn on the output voltage of the sensor, then with Idsn much less than Kn we can assume that Vthn is equal to Vgsn.

By choosing a small value of the Idsn / Kn ratio, the MOS transistor sensor can be introduced into the subthreshold region with the exponential dependence of the drain current on the gate-source voltage, while the output voltage of the sensor Vgsn is less than the threshold voltage and its dependence on the current value is much weaker. At the same time, in the subthreshold region, small changes in the threshold voltage lead to large changes in the output voltage of the sensor and, accordingly, to a stronger dependence of the magnitude of the reverse bias on the threshold voltage.

The equation of state of the inverting amplifier 340 can be written in the form (3)

where Vin is the voltage at the inverting input of the op-amp, approximately equal to Vgsn;

R1 and R2 are the resistances of the divider resistors;

Vbulk is the op amp output voltage used to reverse bias the p-substrate.

Neglecting the zero offset of the amplifier, expressions (3) and taking into account that Vgsn is equal to Vthn, can be written in the form (4):

From expression (4), knowing the values of Vthn, Vref and the required value of Vbulk, we can determine the required value of the ratio of the resistances of the resistors of the divider R2 / R1.

The symmetric scheme of the source of reverse bias of the n-substrate p-MOS transistors according to claims 5, 6 of the Formula shown in FIG. 4 works and is described in a similar way.

To verify the feasibility and evaluation of the parameters, a scheme for the source of negative reverse bias of the p-substrate of 5 V n-channel MOS transistors with 180 nm CMOS technology for use in precision digital-to-analog and analog-to-digital converters was developed. The bias source circuit includes a switching pump charge unit operating with an input clock frequency of Fclk = 2 MHz, a low-power operational amplifier, a polysilicon resistive divider, and a threshold voltage sensor on a MOS transistor with a channel width and length of 8 μm and 0.5 μm, respectively, and source shorted to substrate. The threshold voltage sensor operates at a typical current of 3.6 μA, set by a polysilicon resistor. The entire source circuit is made on 5V MOS transistors and is designed to operate in the range of supply voltages from 3V to 5.5V. In this case, the source circuit was developed taking into account the guarantee of the absence of exceeding the permissible operating voltages of the drain-substrate, source-substrate, gate-source and gate-drain of 5.5V MOS transistors specified by the manufacturer.

The simulation results of the developed scheme of the source of negative reverse bias of the p-substrate of 5 V n-channel MOS transistors in the range of supply voltages are presented in Table 1.

Columns 1 and 2 show the simulation conditions: technological corner (wp-worst power, typ-type process, ws-worst speed) and temperature. It should be noted that the supply voltage of the circuit in the range of 3V-5.5V practically does not affect the results. Columns 3, 4, and 5, 6 show the average voltages at the output of the charge pump and the output of the source (amplifier output) and their ripple amplitudes. Columns 7 and 8 show the threshold voltages of the n-channel MOS transistor with a source shorted to the substrate (Vbulk = 0) and the same MOS transistor with the bias applied to the substrate (Vbulk <0). Columns 9 and 10 show the drain-source leakage currents of an n-channel MOS transistor with a source shorted to the substrate (Vbulk = 0) and the same MOS transistor with the bias applied to the substrate (Vbulk <0).

Table 1 Simulation results of the negative reverse bias source circuit of the p-substrate of n-channel MOS transistors at Vref = 4.1 V Conditions Charge pump block output voltage, mV Amplifier output voltage (Vout = Vbulk), mV Threshold voltage n MOS (Vthn), V Leakage current drain-source, pA / μm corner T ° C average ripple p-p average ripple p-p sensor, Vbulk = 0 with Vbulk <0 Vbulk = 0 with Vbulk <0 one 2 3 four 5 6 7 8 9 10 wp 125 -748 56 -588 0.57 0.74 0.93 47.9 1.30 wp 25 -845 52 -466 0.65 0.82 0.97 0.28 0.01 wp -60 -881 56 -356 0.74 0.89 1.01 0.00 0.00 typ 125 -787 fifty -469 0.49 0.82 0.97 5.92 0.39 typ 25 -895 45 -344 0.58 0.90 1.01 0.00 0.00 typ -60 -915 51 -227 0.67 0.97 1,04 0.00 0.00 ws 125 -857 41 -329 0.44 0.90 1.01 1,69 0.31 ws 25 -964 37 -204 0.52 0.98 1.05 0.00 0.00 ws -60 -971 42 -87 0.60 1.05 1,08 0.00 0.00 | max, min | 971 56 588 0.74 1.05 1,08 47.9 1.3 max-min 223 501 0.31 0.15

As can be seen from the table, the claimed circuit of the reverse bias source of the p-substrate of n-channel MOS transistors reduces the maximum leakage current of the drain-source 5 V MOS transistors with a minimum channel length of 0.5 μm by 37 times from 48 pA to 1.3 pA per micron width channel, reduces the spread of the effective threshold voltage by more than 2 times from 0.31 V to 0.15 V, reduces the amplitude of the ripple at the source output by 76 times from 56 mV to 0.74 mV. Note that the maximum absolute reverse bias of 588 mV was obtained under conditions (wp, 125 ° С) with a minimum threshold voltage of 0.74 V. Under these same conditions, the absolute value of the voltage at the output of the charge pump is significantly larger: 748 mV, which ensures the possibility of further increasing the reverse bias on the p-substrate in the case of a decrease in the threshold voltage of the n-channel MOS transistor-sensor during operation, and thereby, partial compensation for this decrease.

Thus, the inventive method and circuit for reducing leakage and stabilization of threshold voltage of MOS transistors are new, can be implemented and can significantly reduce the leakage current of MOS transistors, as well as reduce the spread and drift of threshold voltage during operation of the IC.

Claims (6)

1. A method of reducing drain-source leakage and stabilizing threshold voltages of MOS transistors in an IC, including generating a ripple voltage by the charge pump and generating a reverse bias voltage of the MOS transistors, characterized in that the ripple voltage with an absolute value greater than the absolute value of the reverse bias voltage of the substrate MOS transistors are converted to a stabilized reverse bias voltage of the MOS transistor substrate, increasing with decreasing threshold voltage voltage of the MOS transistor-sensor. 2. A circuit for reducing drain-source leakage and stabilizing threshold voltages of MOS transistors in an IC, including a source of reverse bias of the substrate relative to the sources, containing a charge pump device and an operational amplifier, and characterized in that the charge pump device generates a ripple voltage with an absolute value that is greater than the absolute the reverse bias voltage of the substrate, the non-inverting input of the operational amplifier is connected to the output of the threshold voltage sensor of the MOS transistors, inverting the input d to the output of the resistive divider connected between the terminals of the reference voltage and the output of the amplifier, and the output of the amplifier forms the output of a reverse bias voltage source and is connected to the substrate of MOS transistors, and the output stage of the operational amplifier is powered from the output of the charge pump. 3. The circuit for reducing drain-source leakage and stabilizing threshold voltages of n-channel MOS transistors in an IC according to claim 2, including a source of negative bias of the p-substrate relative to the sources, and characterized in that the charge pump device generates a pulsating negative voltage with an absolute value greater the absolute value of the voltage of the reverse bias of the substrate, the non-inverting input of the operational amplifier is connected to the output of the threshold voltage sensor of n-channel MOS transistors, the inverting input to the output of the cut a positive divider connected between the terminals of the reference voltage and the output of the amplifier, and the output of the amplifier forms the output of a negative bias voltage source and is connected to the p-substrate of n-channel MOS transistors, the source and substrate of the n-channel MOS transistor of the output stage of the operational amplifier connected to the output of the device charge pump. 4. A circuit for reducing drain-source leakage and stabilizing threshold voltages of n-channel MOS transistors in an IC according to claim 3, characterized in that the threshold voltage sensor of n-channel MOS transistors includes a current-sensing resistor connected between the reference voltage output and the n-channel drain The MOS transistor, the source of which is connected to its substrate and the ground terminal, and the gate connected to the drain forms the output of the sensor, and the ratio of the current set by the current-sensing resistor and the slope of the MOS transistor-sensor determines the slope the dependence of the reverse bias of the substrate on the threshold voltage. 5. A circuit for reducing drain-source leakage and stabilizing threshold voltages of p-channel MOS transistors in an IC according to claim 2, including a source of positive bias of the n-substrate relative to the sources, and characterized in that the charge pump device generates a pulsating voltage with a magnitude greater than the sum of the voltages power supply and positive bias of the n-substrate, the non-inverting input of the operational amplifier is connected to the output of the threshold voltage sensor of p-channel MOS transistors, the inverting input to the output of the resistive divider is included nnogo between ground and the output terminals of the amplifier, and the output of the amplifier constituting the output of the positive bias voltage source and connected to the n-substrate p-channel MOS transistors, the source and the substrate p-channel MOS transistor of the output stage of the operational amplifier is connected to the output of the charge pump device. 6. A circuit for reducing drain-source leakage and stabilizing threshold voltages of p-channel MOS transistors in an IC according to claim 5, characterized in that the threshold voltage sensor of p-channel MOS transistors includes a current-sensing resistor connected between the ground terminal and the drain of the p-channel MOS a transistor, the source of which is connected to its substrate and the power output, and the gate connected to the drain forms the output of the sensor, and the ratio of the current set by the current-setting resistor and the slope of the MOS transistor-sensor determines the slope of selfless substrate bias on the threshold voltage.

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