SU1737730A1 - Device for forming quadrature signals - Google Patents

Abstract

The device relates to the field of radio engineering and can be used in devices with signal processing in quadrature channels. The purpose of the invention is to reduce the change in the amplitude of the orthogonal signal when operating in the frequency range. The device contains a fixed phase shifter 1, an adder 2, a first 3 and a second 4 controlled attenuators, a differential amplifier 5, a multiplier 6, a low-pass filter 7, a quadratic detector 8 and a controlled amplifier 9. Using a quadratic detector 8 and a controlled amplifier 9, the amplitude correction of the output orthogonal signal is used, for which the voltage of the phase error from the output of the filter 7 is used. 2 Il. 1 tab.

Description

The invention relates to the field of radio engineering and can be used in devices with signal processing in quadrature channels,

The purpose of the invention is to reduce the change in the amplitude of the orthogonal signal when operating the device in the frequency range.

Fig. 1 shows a structural diagram of the device proposed: Fig. 2 is a vector diagram explaining its principle of operation.

The quadrature signal shaping device contains a fixed phase shifter 1, an adder 2. a first attenuator 3. a second attenuator 4, a differential amplifier 5, a multiplier 6, a low-pass filter 7, a quadratic detector 8, and a controlled amplifier 9.

The device works as follows.

The input signal of a single amplitude UBX (Fig. 1,2) can be represented as

 & s. where sho is the circular frequency.

The signal at the output of the fixed phase shifter 1 as a result of inaccuracies in the tuning (manufacturing) of the most fixed phase shifter 1, or due to adverse factors, as well as when operating in the frequency range, may have a phase different from 90 ° at some angle tp.

(ufct + y).

We first consider how the phase error p in this device is eliminated and how the orthogonality of the signals at the outputs, i.e., is automatically maintained. . In this case, we will not consider the circuit of automatic control of the amplitude of the output signal, for which we assume that from the output of the quadratic detector there are 8 signals to the control input of the controllable

sl C

NJ

SA) VI VJ CO

ABOUT

silica 9 is not received, and the coefficient of the latter is equal to 1.

Then at the output of the adder 2, the signal appears

 Uex slnfote t + p) + D A cosufcx.

where YES is the amplitude of the signal at the output of the differential amplifier 4.

By rewriting this expression as

U90 ° -Astn (f), where

A - / T + D # -2 AAslnp;

) -YES u cosy)

at the output of multiplier 6, we receive a signal

U6 U90 ° xU0 "Astn (caot + F) -soz

After filter 7 we have:

and A8 pF. Since the output of the filter 7 generates a voltage proportional to (at small F) the phase error F, then when it acts on the controlled attenuators 3 and 4 at the output of the differential amplifier 5, a correction signal Liv is produced (see Fig. 2), condition for the orthogonality of the output signals ().

Now consider how the adjustment of the amplitude of the orthogonal signal.

Suppose that the voltage at the output of the controlled amplifier Uy depends on the voltage Uynp at its control input as follows:

wow about + iopr) -ifv,

That is, the gain K of controlled amplifier 9 depends on Uynp as follows:

K-1 + Uynp,

where Uynp is the voltage at the output of the quadratic detector 8. On the other hand, the voltage at the output of the quadratic detector 8 is

 If.

Combining the last two expressions, we get

K 1 + sln2 p,

This shows that the gain K of the controlled amplifier 9 increases with increasing p and, therefore, the amplitude of the output oscillation of the quadrature output is corrected from the level upwards with increasing p.

Let us estimate the efficiency of the amplitude correction blocks of the orthogonal signal introduced into the proposed device when the device operates in the frequency range (i.e. when the phase shift caused by the fixed phase shifter 1 changes). To do this, we calculate and tabulate the amplitude variation of the signal Ugo0 for cases where the gain of the controlled amplifier 9 is not controlled (- like in the prototype) and if controlled by the law K 1 + sln2 p,

As can be seen from the table, at any values (p, the change in the amplitude of the oscillation Ugo ° from one is less with the operation of the controlled amplifier 9 than with it.

The proposed device is

fundamentally wide-range in frequency and, moreover, can operate over a wide range of temperatures, humidity, etc., since any changes in the phase shift of a fixed phase shifter 1 (leading it away from a value of 90 °) are immediately compensated for in the circuits of the device proposed amplitude correction), in accordance with the described algorithm.

Claims (1)

Invention Formula A quadrature signal shaping device containing a controlled phase shifter and serially connected multiplier and lower filter Frequency inputs of the multiplier are connected to the input and output of the controlled phase shifter, respectively, the output of the low-pass filter is connected to its control input, and the input and output of the controlled phase shifter are the outputs of the device In order to reduce the change in the amplitude of the orthogonal signal when the device operates in the frequency range, the controlled phase shifter is made in the form of a fixed phase shifter, whose input is the input of the controlled phase shifter, controlled amplifier and adder, od which is the output of the controlled a phase shifter, serially connected differential amplifier, the output of which is connected to the second input of the adder, and a quadratic detector, the output of which is connected to the control input of the controlled amplifier, as well as two controlled attenuators with opposite control characteristics, whose inputs are connected to the input of the device, and the outputs - according to direct and the inverted inputs of the differential amplifier, and the control inputs are the control input of the controlled phase shifter. fc / 2