KR20070010684A - Radio receiver and method for matching impedance of antenna using junction capacitance according to voltage change - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a radio receiver and a method for matching an impedance of an antenna using a junction capacitance according to a voltage change.

2. The technical problem to be solved by the invention

In the present invention, when receiving an FM radio signal using an earphone line antenna in a wireless communication terminal incorporating a radio receiver, since the direction of the antenna matching unit and the impedance of the antenna are always changed, RSSI (Received Signal) for optimal antenna impedance matching Strength Indication) Converts the voltage according to the numerical value and adjusts the value of the junction capacitance (capacitor capacitance) according to the voltage change by stage by the variable capacitor diode (Varactor) to maintain the impedance matching of the antenna to improve the FM radio reception sensitivity. The present invention aims to provide a radio receiver and a method for matching an impedance of an antenna by using a junction capacitance according to a voltage change to improve and provide an optimal performance.

3. Summary of Solution to Invention

The present invention provides a radio receiver comprising: an antenna for receiving an FM radio signal; An antenna matching unit connected in series with the antenna; A radio chip for receiving a radio signal through an RF IN terminal; A RSSI (Received Signal Strength Indication) unit for outputting a voltage whose FM reception sensitivity is changed to a predetermined range according to the directionality and the impedance change of the line antenna according to the reception power of the RF IN terminal; An A / D converter (ADC) for converting an analog voltage output from the RSSI unit into a digital voltage; A D / A converter (DAC) for separating the digital voltage from the A / D converter (ADC) step by step and converting the digital voltage into an analog voltage; Multiplexing means for receiving an analog voltage value converted by the D / A converter and selecting and outputting a gain according to a voltage changed in stages; And a variable capacitance diode (Varactor, Baricap) for matching impedance by adjusting the junction capacitance in the antenna matching unit according to the voltage changed in each step.

4. Important uses of the invention

The present invention is used in a wireless communication terminal.

Description

Radio receiver for impedance matching of the antenna by using condenser capacitance according to voltage variation and Method approximate

1 is a view showing an embodiment of applying an antenna impedance by matching a resistor and a capacitor to an ADC according to a voltage change output from an RSSI unit of a conventional FM radio receiver chip;

2 is a block diagram of an embodiment of a radio receiver for matching impedance of an antenna using a junction capacitance according to a voltage change according to the present invention;

3 is a flowchart illustrating a radio reception method in which an impedance of an antenna is matched using a junction capacitance according to a voltage change according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10: RF IN 11: Radio Chip

12: RSSI Part 13: ADC

14: DAC 15: Mux

16: Variable Capacitance Diode (Varactor)

The present invention relates to a radio receiver and a method for matching an impedance of an antenna using a junction capacitance according to a voltage change, and more particularly, to an FM radio signal using an earphone line antenna in a wireless communication terminal having a radio receiver. Since the direction of the antenna matching unit and the impedance of the antenna are always changed when receiving the signal, the voltage is converted according to the received signal strength indication (RSSI) value for optimal antenna impedance matching, and the stepped by the variable capacitor diode (Varactor). The impedance of the antenna using the junction capacitance according to the voltage change to adjust the value of the junction capacitance (capacitor capacitance) according to the voltage change to make the impedance matching of the antenna constant to improve the FM radio reception sensitivity to provide optimal performance. Of a radio receiver and a method for matching the same The.

In the present invention, a wireless communication terminal is a mobile communication terminal, a personal mobile communication terminal (PCS), a personal digital assistant (PDA), a smart phone, a next generation mobile communication terminal (IMT-2000), such as a wireless LAN terminal while carrying the individual A terminal capable of wireless communication.

FIG. 1 is a diagram illustrating an embodiment of applying an antenna impedance by matching a resistor and a capacitor to an ADC according to a voltage change output from an RSSI unit of a conventional FM radio receiver chip.

In general, when receiving an FM radio wave in a wireless communication terminal having a radio receiver, that is, when receiving a radio broadcast signal using an earphone line antenna for FM radio reception, the directionality of the antenna matching unit and the impedance of the antenna are constantly changed. As performance is difficult to expect, the antenna matching unit performs impedance matching using resistance, inductance, and capacitance using RSSI (Received Signal Strength Indication) of the radio receiving chip.

However, by simply adjusting the junction capacitance (capacitance value) by the resistors R1 and R2 and the capacitor C1 according to the change in voltage (0 to V _DD ) output from the RSSI unit 12 of the FM radio receiver chip. It is difficult to keep the impedance matching of the antenna constant.

As described above, the conventional wireless communication terminal incorporating the FM radio receiver uses a compensation circuit by modifying the antenna perpendicular to the receiver through the role of the earphone to improve the FM reception sensitivity, but in terms of performance of the antenna. As the line of the earphone is used as an antenna, it is difficult to expect a constant reception performance such that the directionality and the impedance of the antenna are always changed, and thus there is a problem that the FM reception sensitivity is lowered.

The present invention has been proposed to solve the above problems, and for optimal antenna impedance matching, the voltage is converted according to RSSI (Received Signal Strength Indication) value and the voltage is changed according to the step-by-step voltage change by a variable capacitor (Varactor). Radio impedance matching the impedance of the antenna using the junction capacity according to the voltage change to adjust the value of the junction capacity (capacitor capacity) to make the impedance matching of the antenna constant to improve the FM radio reception sensitivity to provide optimal performance. It is an object of the present invention to provide a receiving apparatus and a method thereof.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. It will also be appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

An apparatus of the present invention for achieving the above object, the radio receiving apparatus, comprising: an antenna for receiving an FM radio signal; An antenna matching unit connected in series with the antenna; A radio chip for receiving a radio signal through an RF IN terminal; A RSSI (Received Signal Strength Indication) unit for outputting a voltage whose FM reception sensitivity is changed to a predetermined range according to the directionality and the impedance change of the line antenna according to the reception power of the RF IN terminal; An A / D converter (ADC) for converting an analog voltage output from the RSSI unit into a digital voltage; A D / A converter (DAC) for separating the digital voltage from the A / D converter (ADC) step by step and converting the digital voltage into an analog voltage; Multiplexing means for receiving an analog voltage value converted by the D / A converter and selecting and outputting a gain according to a voltage changed in stages; And a variable capacitance diode (Varactor, Baricap) for matching the impedance by adjusting the junction capacitance in the antenna matching unit according to the voltage changed in each step.

According to an aspect of the present invention, there is provided a method of receiving a radio signal, the method comprising: receiving a radio signal through an antenna; Outputting, through the RSSI unit, a voltage whose FM reception sensitivity is changed to a predetermined range according to the directionality and the impedance change of the line antenna according to the received power; Converting an analog voltage output from the RSSI unit into a digital voltage; Dividing the digital voltage step by step and converting the digital voltage into an analog voltage; Selecting and outputting a gain according to the voltage which is changed step by step by converting the converted analog voltage value; And adjusting the variable junction capacitance by the variable capacitance diode according to the electric field according to the voltage which is changed in stages to always maintain the constant impedance matching of the antenna matching unit.

The above objects, features, and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. Could be. In describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of an embodiment of a radio receiver for matching an impedance of an antenna using a junction capacitance according to a voltage change according to the present invention.

As shown in FIG. 2, a radio receiving apparatus in which an impedance of an antenna is matched using a junction capacitance according to a voltage change according to the present invention includes an earphone line antenna (ANT) for receiving an FM radio signal and a serial with the antenna. A radio chip 11 for receiving a radio signal through an inductor L, a resistor R, and an RF IN terminal 10 connected to the radio chip 11 and the radio chip 11, and an FM radio receiver RX-FRONT- RSSI (Received Signal Strength Indication) unit 12 for outputting a voltage whose FM reception sensitivity is changed from 0V to VDD according to the directionality and the impedance change of the line antenna according to the received power of the RF IN terminal 10 connected to the END). ), An A / D converter (ADC) 13 and the A / D converter 13 for converting an analog voltage output from the RSSI unit 12 into a digital voltage according to the signal received by the radio chip 11. Dividing digital voltage from 3 steps D / A converter (DAC) 14 for converting to analog voltage and the analog voltage value converted by the D / A converter 14 is inputted voltage (step 1, 0V ~ 1.2V, LOW voltage), (2 phases, 1.3V ~ 2V, MID voltage), (3 phases, 2.1V ~ VDD, HIGH voltage)), and a strong electric field (G0, HIGH voltage), a medium electric field (G1, MID voltage) , The mux 15 for selecting and outputting a gain according to the weak electric field (G2, LOW voltage), and if the voltage in the reverse direction is high so that the antenna matching unit always matches the optimum impedance according to the voltage change step by step, the junction capacitance (Capacitor capacitance, capacitance value) includes a variable capacitance diode (Varactor, Barricap) (16) for adjusting the variable junction capacitance through the characteristic that the junction capacity is increased when the voltage is low and the voltage is low.

The present invention adjusts the variable junction capacitance matching of the antenna matching unit in accordance with the step-by-step voltage change of the received radio signal using the RSSI (Received Signal Strength Indication) unit 12 of the radio chip 11, thereby always providing a constant impedance. The variable capacitance diode 16 is used to match and improve the FM reception sensitivity.

When receiving an FM radio signal using an earphone line antenna in a wireless communication terminal having a built-in radio receiver, the RSSI unit has an FM reception sensitivity depending on the directionality and the impedance of the line antenna according to the received power. The output voltage (0V to VDD) changed to (12) is output.

The output voltage of the RSSI unit 12 according to the reception of the radio signal is separated into the DAC 14 in three stages through the ADC 13 and input to the mux 15 so that the first stage (0 V to 1.2 V, LOW) is output. Voltage), two phases (1.3V ~ 2V, MID voltage), three phases (2.1V ~ VDD, HIGH voltage) and are divided into the variable capacitance diodes (Varactor, antenna matching part) according to the strong electric field, the medium electric field, and the weak electric field. Baricap) 16 is used to adjust the junction capacitance (capacitance value) according to the voltage change.

In this way, the impedance change is a change in the FM reception sensitivity, so that the antenna matching structure has a three-stage junction capacitance by supplying voltages from stage 1 to stage 3. If the output of the mux 15 in the variable capacitance diode (Varactor, Barri Cap) 16 is a strong electric field (if the reception field is good), three stages (2.1V ~ VDD) having a high voltage is applied, and if the medium field is MID The second stage (1.3V ~ 2V) with voltage is applied, and the first stage (0V ~ 1.2V) with LOW voltage is applied to the weak electric field to adjust the junction capacitance (capacitance value).

The variable capacitance diode 16 determines the step-by-step voltage applied from the RSSI unit 12 when it is impossible to listen to the broadcast according to the portable state or the direction of the headphone line while listening to the FM broadcast. Adjust the junction capacitance to keep the impedance matching constant.

The variable capacitance diode 16 adjusts the variable junction capacitance through a characteristic in which the junction capacitance decreases when the reverse voltage is high (HIGH voltage) and when the voltage is low (LOW voltage). Optimum impedance matching is kept constant in the matching unit to increase the reception sensitivity of the FM radio.

The variable capacitance diode 16 lowers the junction capacitance according to the HIGH voltage (step 3) in the case of a strong field, maintains a predetermined junction capacity in the MID voltage (step 2) in the case of a medium field, and low voltage (1) in the case of a weak field. By increasing the junction capacity according to the step), the impedance matching of the antenna is always kept constant to improve the reception sensitivity of the FM radio.

Referring to FIG. 2, the hysteresis curve for determining the gain of the antenna according to the radio reception power is controlled by the FM radio. At this time, the mux 15 is controlled by G0, G1, and G2 according to the strong electric field, the medium electric field, and the weak electric field to adjust the impedance of the antenna by adjusting the junction capacitance according to the stepwise voltage change in the variable capacitance diode 16. Keep constant to improve the efficiency of FM radio reception.

Since the FM radio receiver does not need to lengthen the length of the headphone wire due to the FM reception sensitivity compensation function according to the optimum impedance matching, practicality and convenience are emphasized.

3 is a flowchart illustrating a radio reception method in which an impedance of an antenna is matched using a junction capacitance according to a voltage change according to the present invention.

First, an FM radio signal is received through an antenna ANT at an FM radio receiver RX-FRONT-END (100), and a radio chip connected to the FM radio receiver RX-FRONT-END at a radio chip 11. According to the received power input to the RF IN terminal 10 of (11), an output of a voltage whose FM reception sensitivity is changed from 0V to VDD due to the directionality and the impedance change of the line antenna is output through the RSSI unit 12 (101). .

The analog voltage output from the RSSI unit 12 is converted into a digital voltage by the ADC 13 (102), and the digital voltage is converted into an analog voltage by the DAC 14 (103).

Receiving the D / A converted analog voltage value, the voltage divided into three stages from the mux 15 ((step 1, 0V ~ 1.2V, LOW voltage), (step 2, 1.3V ~ 2V, MID voltage), (Step 3, 2.1V to VDD, HIGH voltage) selects and outputs the gain according to the strong electric field (G0, HIGH voltage), the medium electric field (G1, MID voltage), and the weak electric field (G2, LOW voltage) (104). ).

In the variable capacitor diode (Varactor) (16), the higher the reverse voltage output from the mux 15, the smaller the junction capacitance (capacitance value), the lower the reverse voltage, the variable junction capacitance through the characteristics of higher junction capacity By adjusting the voltage, the impedance matching of the antenna matching unit is constantly maintained according to the step-by-step voltage change, thereby improving the reception sensitivity efficiency of the FM radio (105).

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

The present invention as described above, the antenna (ANT) impedance matching according to the step-by-step voltage change by the variable capacitance diode used to improve the FM reception sensitivity in a wireless communication terminal with a built-in radio receiver to optimize the impedance of the antenna By using the value, the antenna is less affected by the actual headphone line by using the ground line of the headphone line, and there is an effect of improving the FM reception sensitivity because the radio broadcast listening is not impossible depending on the direction.

In addition, when the FM reception sensitivity of a wireless communication terminal having a radio receiver is lowered, it is converted to MONO, and thus it is difficult to listen to high quality. Therefore, the impedance matching of the antenna is kept constant to improve reception sensitivity. This allows the reception of an optimum high quality FM stereo broadcast.

Claims (4)

In the radio receiver, An antenna for receiving an FM radio signal; An antenna matching unit connected in series with the antenna; A radio chip for receiving a radio signal through an RF IN terminal; A RSSI (Received Signal Strength Indication) unit for outputting a voltage whose FM reception sensitivity is changed to a predetermined range according to the directionality and the impedance change of the line antenna according to the reception power of the RF IN terminal; An A / D converter (ADC) for converting an analog voltage output from the RSSI unit into a digital voltage; A D / A converter (DAC) for separating the digital voltage from the A / D converter (ADC) step by step and converting the digital voltage into an analog voltage; Multiplexing means for receiving an analog voltage value converted by the D / A converter and selecting and outputting a gain according to a voltage changed in stages; And Variable capacitance diode (Varactor, Barricap) for matching the impedance by adjusting the junction capacitance in the antenna matching unit according to the voltage changed in each step Radio receiving device matching the impedance of the antenna by using a junction capacitance according to the voltage change including a. The method of claim 1, The variable capacitance diode, Voltage change, characterized in that the impedance matching of the antenna is kept constant by adjusting the junction capacitance in accordance with the electric field of the reverse voltage which is changed in the step (for example, step 1, step 2, step 3) applied from the multiplexing means. Radio receiving apparatus matching the impedance of the antenna by using the junction capacity according to. The method according to claim 1 or 2, The variable capacitance diode, The output of the multiplexing means is a strong electric field G0, 2.1 V to V _DD , HIGH voltage, 3 stages), lowers the junction capacitance of the antenna matching unit, and maintains a predetermined junction capacitance if the medium field (G1, 1.3V ~ 2V, MID voltage, 2 stages), and weak field (G2, 0V ~ 1.2). V, LOW voltage, step 1) is a radio receiving device that matches the impedance of the antenna using the junction capacity according to the voltage change, characterized in that the impedance matching of the antenna is always maintained by increasing the junction capacitance. In the radio receiving method, Receiving a radio signal via an antenna; Outputting, through the RSSI unit, a voltage whose FM reception sensitivity is changed to a predetermined range according to the directionality and the impedance change of the line antenna according to the received power; Converting an analog voltage output from the RSSI unit into a digital voltage; Dividing the digital voltage step by step and converting the digital voltage into an analog voltage; Selecting and outputting a gain according to the voltage which is changed step by step by converting the converted analog voltage value; And Adjusting the variable junction capacitance by the variable capacitance diode according to the electric field according to the voltage changed in step by step to always maintain constant impedance matching of the antenna matching unit Radio receiving method matching the impedance of the antenna by using a junction capacitance according to the voltage change including a.

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