Voltage-controlled oscillator

Abstract

This invention provides a voltage-controlled oscillator that reduces phase noise and expands the range of communication frequencies. [Solution] A voltage-controlled oscillator used in a communication circuit, comprising a cross-coupling circuit 21 and a transmission line module 22, wherein the cross-coupling circuit has a first transistor 211, a first capacitor 212, a second transistor 213 and a second capacitor 214, and the transmission line module has a first transmission line unit 221 and a second transmission line unit 222, thereby further achieving the objective of reducing the phase noise of the voltage-controlled oscillator and expanding the communication frequency range by eliminating the transmission line effect of the cross-coupling circuit with the transmission line module.

Description

Technical Field

[0001] The present invention relates to a voltage-controlled oscillator, and more particularly, to the structure of a voltage-controlled oscillator especially used in a communication circuit.

Background Art

[0002] With the rapid development of communication systems, the requirements for communication circuits applied to the communication systems are becoming increasingly high. In order to improve the noise tolerance of the communication circuit, the voltage-controlled oscillator is often used to enhance the noise tolerance of the communication circuit.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Conventionally, Class-F voltage-controlled oscillators increase the oscillation voltage of the communication circuit by a coupled winding unit, and acquire an additional impedance peak through the third harmonic effect, thereby forming a pseudo-square wave output voltage. Refer to Figure 1, which is a schematic diagram of a Class-F voltage-controlled oscillator of Chinese Patent No. CN110677127. As shown in the drawing, the voltage-controlled oscillator includes a first oscillation chamber 11, a cross-coupling circuit 12, and a second oscillation chamber 13, wherein the cross-coupling circuit 12 has a first transistor 121 and a second transistor 122, the gate of the first transistor 121 is electrically connected to the drain of the second transistor 122, and the drain of the first transistor 121 is electrically connected to the gate of the second transistor 122, the first oscillation chamber 11 has a first capacitor 111, a second capacitor 112, and an inductor 113, the first capacitor 111, the second capacitor 112, and the inductor 113 are connected in parallel, and the two ends are electrically connected to the drains of the first transistor 121 and the second transistor 122, respectively, and the two connected ends function as the output terminal A and input terminal B of the voltage-controlled oscillator, the first oscillation chamber 11 generates an impedance of 1x, and the second oscillation chamber 13 generates an impedance of 3x. This type of impedance suppression design reduces the effectiveness of Class-F and also increases the circuit area required for such a design. [Means for solving the problem]

[0004] In view of the shortcomings of the prior art described above, the main object of the present invention is to provide a voltage-controlled oscillator for use in a communication circuit, which includes a cross-coupling circuit and a transmission line module. The cross-coupling circuit comprises a first transistor, a first capacitor, a second transistor, and a second capacitor, with one end of the first capacitor electrically connected to the drain of the first transistor, and one end of the second capacitor electrically connected to the drain of the second transistor. The transmission line module is electrically connected to the cross-coupling circuit and comprises a first transmission line unit and a second transmission line unit, with one end of the first transmission line unit electrically connected to the other end of the second capacitor, the other end of the first transmission line unit electrically connected to the gate of the first transistor, one end of the second transmission line unit electrically connected to the other end of the first capacitor, and the other end of the second transmission line unit electrically connected to the gate of the second transistor. By eliminating the transmission line effect of the cross-coupling circuit with the transmission line module, the objective of reducing the phase noise of the voltage-controlled oscillator and expanding the communication frequency range is further achieved. The transmission line module further includes a first resistor, one end of which is electrically connected to the gate of the first transistor and the other end of the first transmission line unit, and a second resistor, one end of which is electrically connected to the gate of the second transistor and the other end of the second transmission line unit.

[0005] The first and second transistors of the voltage-controlled oscillator according to the present invention are field-effect transistors.

[0006] The voltage-controlled oscillator transmission line module according to the present invention further includes a third capacitor, one end of which is electrically connected to the one end of the first transmission line unit, and the other end of which is electrically connected to the one end of the second transmission line unit. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram of a Class-F voltage-controlled oscillator disclosed in Chinese Patent No. CN110677127. [Figure 2] This is a schematic diagram of Embodiment 1 of the voltage-controlled oscillator according to the present invention. [Figure 3] This is a schematic diagram of Embodiment 2 of the voltage-controlled oscillator according to the present invention. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to specific examples. Those skilled in the art will be able to understand other advantages and effects of the present invention from the information disclosed herein.

[0009] Referring to Figure 2, which is a schematic diagram of Embodiment 1 of the voltage-controlled oscillator according to the present invention, Figure 2 shows a voltage-controlled oscillator used in a communication circuit. The voltage-controlled oscillator includes a cross-coupling circuit 21 and a transmission line module 22, the cross-coupling circuit 21 having a first transistor 211, a first capacitor 212, a second transistor 213 and a second capacitor 214, one end of the first capacitor 212 being electrically connected to the drain S1 of the first transistor 211, one end of the second capacitor 214 being electrically connected to the drain S2 of the second transistor 214, the source (not shown) of the first transistor 211 being electrically connected to the ground terminal, the other end of the first capacitor 212 being electrically connected to one end of the second transmission line unit 222, the source (not shown) of the second transistor 213 being electrically connected to the ground terminal, and the other end of the second capacitor 214 being electrically connected to one end of the first transmission line unit 221. Furthermore, the gate G1 of the first transistor 211 and the other end of the first transmission line unit 221 are electrically connected to one end of the first resistor 223, the gate G2 of the second transistor 213 and the other end of the second transmission line unit 222 are electrically connected to one end of the second resistor 224, and the other end of the first resistor 223 and the other end of the second resistor 224 are electrically connected to each other.

[0010] The transmission line module 22 is electrically connected to the cross-coupling circuit 21. The transmission line module 22 has a first transmission line unit 221 and a second transmission line unit 222. One end of the first transmission line unit 221 is electrically connected to the other end of the second capacitor 214, and the other end of the first transmission line unit 221 is electrically connected to the gate G1 of the first transistor 211. One end of the second transmission line unit 222 is electrically connected to the other end of the first capacitor 212, and the other end of the second transmission line unit 222 is electrically connected to the gate G2 of the second transistor 213. By eliminating the transmission line effect of the cross-coupling circuit 21 with the transmission line module 22, the objective of reducing the phase noise of the voltage-controlled oscillator and expanding the communication frequency range is further achieved. More specifically, the transmission line module 22 (equivalent to an inductor) and the first capacitor 212 / second capacitor 214 facilitate the generation of negative resistance at low frequencies. Since negative resistance eliminates positive resistance in the first oscillation chamber, this makes it easier to achieve the oscillation initiation conditions, reduce transistor size, lower power consumption, reduce phase noise, and further achieve the objectives of expanding the communication frequency range.

[0011] Furthermore, the inductance value of the transmission line module 22 and the capacitance values ​​of the first capacitor 212 / second capacitor 214 can provide oscillation initiation conditions by appropriately adjusting the negative resistance value. As shown in the following equation, L ML4 C is the inductance of the transmission line. gs This is the parasitic resistance of the transistor.

[0012]

number

[0013] Referring to Figure 3, which is a schematic diagram of Embodiment 2 of the voltage-controlled oscillator according to the present invention, as shown in the drawing, in order to improve the frequency tripling effect generated by the voltage-controlled oscillator, the gate G1 of the first transistor 211 and the other end of the first transmission line unit 221 are electrically connected to one end of the first resistor 223, the gate G2 of the second transistor 213 and the other end of the second transmission line unit 222 are electrically connected to one end of the second resistor 224, and the other end of the first resistor 223 and the other end of the second resistor 224 are electrically connected to each other. In addition, a third capacitor 225 is electrically connected between the one end of the first transmission line unit 221 and the one end of the second transmission line unit 222. More specifically, one end of the third capacitor 225 is electrically connected to the one end of the first transmission line unit 221, and the other end of the third capacitor 225 is electrically connected to the one end of the second transmission line unit 222. The first resistor 223, the second resistor 224, and the third capacitor 225 can strengthen the impedance generated by the voltage-controlled oscillator, thereby bringing the waveform output from the voltage-controlled oscillator closer to a square wave, and thus achieving the objective of enhancing the phase noise removal of the communication circuit by the voltage-controlled oscillator. More specifically, the third capacitor 225, the first transmission line unit 221 / second transmission line unit 222, and the first capacitor 212 / second capacitor 214 generate a third harmonic, and an additional impedance peak can be obtained at three times the frequency, thereby bringing the waveform output from the voltage-controlled oscillator closer to a square wave, and thus achieving the objective of enhancing the phase noise removal of the communication circuit by the voltage-controlled oscillator. Thus, the voltage-controlled oscillator according to the present invention is modified by replacing the second oscillation chamber 13 in Figure 1 with a third capacitor 225.

[0014] The above embodiments merely exemplarily explain the features and effects of the present invention, and are not intended to limit the scope of the substantial technical content of the present invention. A person skilled in the art can modify and change the above embodiments without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the rights of the present invention is as set forth in the claims described below.

Explanation of Reference Numerals

[0015] 11 First oscillation chamber 12 Cross-coupling circuit 13 Second oscillation chamber 111 First capacitor 112 Second capacitor 113 Inductor 121 First transistor 122 Second transistor 21 Cross-coupling circuit 22 Transmission line module 211 First transistor 212 First capacitor 213 Second transistor 214 Second capacitor 221 First transmission line unit 222 Second transmission line unit 223 First resistor 224 Second resistor 225 Third capacitor A Output terminal B Input terminal S1, S2 Drain G1, G2 Gate

Claims

1. A voltage-controlled oscillator used in communication circuits, A cross-coupling circuit having a first transistor, a first capacitor, a second transistor, and a second capacitor, wherein one end of the first capacitor is electrically connected to the drain of the first transistor, and one end of the second capacitor is electrically connected to the drain of the second transistor. A transmission line module electrically connected to the cross-coupling circuit and having a first transmission line unit and a second transmission line unit, wherein one end of the first transmission line unit is electrically connected to the other end of the second capacitor, the other end of the first transmission line unit is electrically connected to the gate of the first transistor, one end of the second transmission line unit is electrically connected to the other end of the first capacitor, and the other end of the second transmission line unit is electrically connected to the gate of the second transistor, and the transmission line module reduces the phase noise of the voltage-controlled oscillator by eliminating the transmission line effect of the cross-coupling circuit. The aforementioned transmission line module is A first resistor, one end of which is electrically connected to the gate of the first transistor and the other end of the first transmission line unit, The system further includes a second resistor, one end of which is electrically connected to the gate of the second transistor and the other end of the second transmission line unit, The other end of the first resistor and the other end of the second resistor are electrically connected to each other. Voltage-controlled oscillator.

2. The first and second transistors are field-effect transistors. The voltage-controlled oscillator according to claim 1.

3. The transmission line module further includes a third capacitor, one end of which is electrically connected to the one end of the first transmission line unit, and the other end of which is electrically connected to the one end of the second transmission line unit. The voltage-controlled oscillator according to claim 1.

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