TWI399919B - Self-adjustable impedance matching circuit - Google Patents

Description

Adaptive impedance matching circuit

The present invention relates to a microwave circuit, and more particularly to an adaptive impedance matching circuit.

The impedance of the load in the microwave circuit must match the impedance of the pre-stage circuit to optimize the performance of the microwave circuit. For this reason, an impedance matching circuit is designed in the microwave circuit. The impedance value of the existing impedance matching circuit is fixed. However, for a microwave product with more and more functions, the load will vary within a certain range during use, which may cause mismatch of the impedance matching circuit, thereby affecting The performance of microwave circuits.

In view of this, it is necessary to provide an adaptive impedance matching circuit that can automatically adjust its impedance according to the variation of the load to achieve timely impedance matching.

An adaptive impedance matching circuit includes an input terminal, an output terminal, a variable impedance circuit, first and second directional couplers, a subtraction unit, and an adjustment unit. A variable impedance circuit is coupled between the input terminal and the output terminal, the variable impedance circuit including a variable capacitor. A first directional coupler is coupled between the variable impedance circuit and the input for measuring an input power of the input. a second directional coupler is connected between the variable impedance circuit and the output end, The output power of the output is measured. A subtraction unit is coupled between the first directional coupler and the second directional coupler for calculating a difference between the input power and the output power. The adjusting unit is connected between the subtracting unit and the variable impedance circuit for adjusting a bias voltage of the variable capacitor according to the difference, thereby changing an impedance value of the variable impedance circuit to achieve timely impedance matching.

When the output power fluctuates due to the load change, the present invention can automatically adjust the impedance of the variable impedance circuit according to the power difference between the input end and the output end, thereby achieving timely impedance matching between the load and the pre-stage circuit.

10‧‧‧Pre-stage circuit

20‧‧‧Adaptive impedance matching circuit

21‧‧‧ input

22‧‧‧First directional coupler

24‧‧‧Second directional coupler

23‧‧‧Variable impedance circuit

231‧‧‧ input

232, 233‧‧‧ fixed capacitor

234‧‧‧Inductance components

235‧‧‧output

236‧‧‧ Grounding

237‧‧‧Variable Capacitance

238‧‧‧resistance

239‧‧‧ Adjusting end

25‧‧‧ Output

26, 28‧‧‧AC/DC converter module

27‧‧‧Adjustment unit

271‧‧‧Power supply

29, 31‧ ‧ amplifier

30‧‧‧Subtraction unit

40‧‧‧ load

P1, P2‧‧‧ power

S‧‧‧Difference

1 is a circuit block diagram of an adaptive impedance matching circuit according to an embodiment of the present invention.

2 is a circuit diagram of a variable impedance circuit of the adaptive impedance circuit of FIG. 1.

The automatic inspection method and inspection system for the injection molded workpiece provided by the present invention will be further described in detail below with reference to the accompanying drawings.

Referring to FIG. 1 and FIG. 2, an adaptive impedance matching circuit 20 according to an embodiment of the present invention is provided. The adaptive impedance matching circuit 20 includes an input 21 and an output 25, the input 21 being coupled to a pre-stage circuit 10, the output 25 being coupled to a load 40, the impedance of the load 40 being used The process changes within a certain range.

The adaptive impedance matching circuit 20 includes a variable impedance circuit 23, a first directional coupler 22, a second directional coupler 24, and an AC/DC (AC/DC) conversion module 26. 28. An amplifier 29, 31, a subtraction unit 30, an adjustment unit 27, and a power supply 271. The input of the first directional coupler 22 is connected to the input 21 of the adaptive impedance matching circuit 20, the output of the first directional coupler 22 is connected to the input 231 of the variable impedance circuit 23, and the second directional coupler 24 The input terminal is connected to the output terminal 235 of the variable impedance circuit 23, and the output terminal of the second directional coupler 24 is connected to the output terminal 25. The coupling end of the first directional coupler 22 is connected to the input end of the AC/DC conversion module 26, the output end of the AC/DC conversion module 26 is connected to the input end of the amplifier 29, and the output end of the amplifier 29 is connected to one of the subtraction units 30. The input end of the second directional coupler 24 is connected to the input end of the AC/DC converter module 28, the output end of the AC/DC converter module 28 is connected to the input end of the amplifier 31, and the output end of the amplifier 31 is connected to the subtraction unit 30. Another input. The output of the subtraction unit 30 is connected to the input of the adjustment unit 27, and the output of the adjustment unit 27 is connected to the adjustment terminal 239 of the variable impedance circuit 23. The power supply 271 is connected to the adjustment unit 27 to supply power to the adjustment unit 27.

The first directional coupler 22 is used to measure the power P1 of the input 21 of the impedance matching circuit 20, that is, the output power of the pre-stage circuit 10. In the present embodiment, the magnitude of the power is represented by an alternating current value. The power signal P1 is converted into a DC signal by the AC/DC conversion module 26, amplified by the amplifier 29, and input to the subtraction unit 30. Of course, in other embodiments, other electrical signals may also be used to characterize the power P1, such as voltage.

The second directional coupler 24 is used to measure the power P2 of the output 25 of the impedance matching circuit 20, ie the power applied to the load 40. The power signal P2 is converted into a DC signal by the AC/DC conversion module 28, amplified by the amplifier 31, and input to the subtraction method. Unit 30.

The subtraction unit 30 is for calculating the difference S of the powers P1 and P2, and outputs the difference S to the adjustment unit 27. The adjusting unit 27 is for adjusting the impedance value of the variable impedance circuit 23 according to the difference S until P1 and P2 are equal. In the present embodiment, the power source 271 supplies the adjustment unit 27 with the voltage required for the adjustment, and the adjustment unit 27 changes the impedance value of the variable impedance circuit 23 by adjusting the bias voltage applied to the variable impedance circuit 23.

The above directional coupler, AC/DC conversion module, amplifier, subtraction unit, and adjustment unit are well known to those skilled in the art, and the specific structure of the above components will not be described here.

The variable impedance circuit 23 includes fixed capacitors 232, 233, an inductive element 234, a variable capacitor 237, and a resistor 238. The inductance element 234 is connected at one end to the output terminal 235 of the variable impedance circuit 23, and at the other end to the one end of the fixed capacitor 233. One end of the fixed capacitor 232 is connected to the input terminal 231 of the variable impedance circuit 23. The other ends of the fixed capacitors 232, 233 are connected to each other. The variable capacitor 237 has one end connected between the fixed capacitors 232 and 233 and the other end connected to the ground end 236. One end of the resistor 238 is connected between the fixed capacitors 232, 233, and the other end is connected to the regulating end 239 of the variable impedance circuit 23.

The inductance element 234 and the variable capacitor 237 are used to form an LC circuit, and the bias voltage is applied to change the capacitance value of the capacitor 237 to change the impedance of the LC circuit. The resistor 238 is for receiving the voltage applied from the adjustment unit 27 and applying the voltage to the variable capacitor 237. Fixed capacitors 232, 233 are used to isolate DC points in the circuit The amount is ensured that it will not be applied to the load 40.

The specific values of the capacitor, the inductor, and the resistor can be determined according to actual conditions. For example, when the resistance of the load 40 is designed to be 50 ohms, the inductance of the inductor element 234 can be designed to be 469 uH, and the capacitance range of the variable capacitor 237 can be designed as 5.8uF~0.37uF, correspondingly, the bias voltage applied to the variable capacitor 237 ranges from 0 to 40V DC, the resistance of the resistor 238 is 0 ohm, and the capacitance of the fixed capacitors 232 and 233 is 50 pF, respectively. At this time, the impedance range of the impedance matching circuit 20 is (0.1-j2.9)~(34.1-j33.7) Ohm.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. However, the above description is only the preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiments, and equivalent modifications or variations made by those skilled in the art in light of the spirit of the present invention are It should be covered by the following patent application.

10‧‧‧Pre-stage circuit

20‧‧‧Adaptive impedance matching circuit

21‧‧‧ input

22‧‧‧First directional coupler

24‧‧‧Second directional coupler

23‧‧‧Variable impedance circuit

25‧‧‧ Output

26, 28‧‧‧AC/DC converter module

27‧‧‧Adjustment unit

271‧‧‧Power supply

29, 31‧ ‧ amplifier

30‧‧‧Subtraction unit

40‧‧‧ load

P1, P2‧‧‧ power

S‧‧‧Difference

Claims (8)

An adaptive impedance matching circuit includes an input end; an output end; a variable impedance circuit connected between the input end and the output end, the variable impedance circuit comprising a variable capacitor, the variable capacitor The capacitance value ranges from 5.8uF to 0.37uF, and the impedance value of the variable impedance circuit ranges from (0.1-j2.9) to (34.1-j33.7) Ohm; one is connected to the variable impedance circuit and the input terminal a first directional coupler for measuring the input power of the input: a second directional coupler connected between the variable impedance circuit and the output for measuring the output power of the output; a subtracting unit between the first directional coupler and the second directional coupler, configured to calculate a difference between the input power and the output power; and a connection between the subtracting unit and the variable impedance circuit And an adjusting unit configured to adjust a bias voltage of the variable capacitor according to the difference, thereby changing an impedance value of the variable impedance circuit to achieve timely impedance matching. The adaptive impedance matching circuit of claim 1, wherein the power measured by the first directional coupler and the second directional coupler is represented by an alternating current signal, and the adaptive impedance matching circuit further includes a connection. a first AC/DC conversion module between the first directional coupler and the subtraction unit, and a second AC/DC conversion module connected between the second directional coupler and the subtraction unit And for converting the AC signals measured by the first directional coupler and the second directional coupler into DC signals, respectively. The adaptive impedance matching circuit of claim 2, further comprising a first amplifier connected between the first AC/DC conversion module and the subtraction unit, and connected to the second intersection/ a second amplifier between the DC conversion module and the subtracting unit for respectively amplifying the power signal measured by the first directional coupler and the second directional coupler and outputting the amplified signal to the subtracting unit . The adaptive impedance matching circuit of claim 1, further comprising a power source connected to the adjusting unit for supplying power to the adjusting unit. The adaptive impedance matching circuit of claim 1, wherein the variable impedance circuit further includes a first fixed capacitor and a second fixed capacitor, the first fixed capacitor being connected to the input end, the second One end of the fixed capacitor is connected to the output end, and the other ends of the first fixed capacitor and the second fixed capacitor are connected to each other. The adaptive impedance matching circuit of claim 5, wherein the variable capacitor is grounded at one end, and the other end is connected between the first fixed capacitor and the second fixed capacitor and further connected to the adjusting unit. The adaptive impedance matching circuit of claim 6, wherein the variable impedance circuit further comprises a resistor connected to the adjusting unit through the resistor. The adaptive impedance matching circuit of claim 5, wherein the variable impedance circuit further comprises an inductor, and the second fixed capacitor passes the inductor Connect to this output.