CN-122001303-A - W-band low-noise voltage-controlled oscillator based on transformer resonant cavity and harmonic extraction

CN122001303ACN 122001303 ACN122001303 ACN 122001303ACN-122001303-A

Abstract

The invention relates to a W-band low-noise voltage-controlled oscillator based on transformer resonant cavity and harmonic extraction, which comprises a dual-core in-phase coupled oscillator core, a two-bit switch capacitor group, a linearization variable capacitor group and an output buffer, wherein the dual-core in-phase coupled oscillator core comprises a transformer resonant cavity and a harmonic extraction network, a fundamental wave oscillation signal is generated in the transformer resonant cavity and is coupled and output to the output buffer, a high-power second harmonic oscillation signal is generated in the harmonic extraction network and is output as a target oscillation signal, the two-bit switch capacitor group adopts an HBT switch with excellent high-frequency performance, the tuning range of the oscillator is divided into four sub-bands, the tuning gain is reduced, the capacitance value of the linearization variable capacitor group is linearly changed along with the tuning voltage, the conversion mechanism of flicker noise is restrained, and the output buffer realizes load isolation and buffering of the fundamental wave oscillation signal. The voltage-controlled oscillator has low tuning gain and high output power in the W wave band, and realizes excellent phase noise.

Inventors

LU QIJUN
CHEN YIFU
CHEN LINHE
ZHANG TAO
AN XIN
LIU BEI
ZHU ZHANGMING

Assignees

西安电子科技大学

Dates

Publication Date: 20260508
Application Date: 20251229

Claims (10)

1. The W-band low-noise voltage-controlled oscillator based on transformer resonant cavity and harmonic extraction is characterized by comprising a dual-core in-phase coupled oscillator core, a two-bit switched capacitor group, a linearization variable capacitor group and an output buffer; The dual-core in-phase coupled oscillator core is used for generating a fundamental wave oscillation signal based on the discrete capacitance value and the fine tuning capacitance value and coupling the fundamental wave oscillation signal to the output buffer, and the harmonic extraction network is used for extracting a second harmonic from the fundamental wave oscillation signal and performing power synthesis to generate and output a target oscillation signal LO 1 of a W wave band; The two-bit switch capacitor group is configured to provide corresponding discrete capacitance values for the dual-core in-phase coupled oscillator core in response to the binary state combination of the switch control voltage V S1 and the switch control voltage V S2 , so as to divide the total tuning range of the oscillation frequency output by the dual-core in-phase coupled oscillator core into a plurality of discrete sub-bands that overlap with each other, and realize step-by-step tuning of the oscillation frequency; The linearization variable capacitor group is used for responding to a continuously-changing direct-current control voltage signal V T and outputting a fine-tuning capacitance value, and the fine-tuning capacitance value is used for continuously adjusting the oscillation frequency in any sub-frequency band determined by the two-bit switch capacitor group; The output buffer is used for carrying out load isolation and buffering on the fundamental oscillation signals and outputting two paths of fundamental oscillation signals LO 2 and LO 3 in a differential mode.
2. The W-band low-noise voltage controlled oscillator based on transformer resonant cavity and harmonic extraction of claim 1, wherein the dual-core in-phase coupled oscillator core comprises a first transformer resonant cavity, a second transformer resonant cavity, a harmonic extraction network, a first oscillator core and a second oscillator core; The first transformer resonant cavity and the second transformer resonant cavity have the same structure; the first oscillator core and the second oscillator core are identical in structure; The first oscillator core is connected with the first transformer resonant cavity, and the second oscillator core is connected with the second transformer resonant cavity; The first oscillator core and the second oscillator core are connected to a node V E1 、V E2 to realize in-phase coupling, so that the first oscillator core and the second oscillator core generate fundamental wave oscillation signals with the same amplitude, frequency and phase; the first transformer resonant cavity and the second transformer resonant cavity multiplex capacitances provided by the two-bit switched capacitor group and the linearization variable capacitor group to determine the frequency of the fundamental oscillation signal; The harmonic extraction network is used for respectively extracting second harmonic signals from common mode nodes in the first oscillator core and the second oscillator core and positioned at the collector of the transistor, and performing power synthesis on the extracted second harmonic signals to generate the target oscillation signal LO 1 ; The fundamental oscillation signal is coupled and output to the output buffer through two transformer resonant cavities.
3. The W-band low-noise voltage-controlled oscillator based on transformer resonant cavity and harmonic extraction according to claim 2, wherein, The first transformer resonant cavity comprises an inductor L1 and an inductor L2, and the second transformer resonant cavity comprises an inductor L3 and an inductor L4, wherein the coupling coefficients of the two transformer resonant cavities are the same; the harmonic extraction network comprises a transmission line TL1, a transmission line TL2, a transmission line TL3, a transmission line TL4, a transmission line TL5 and a capacitor C1; the first oscillator core comprises a transistor Q1, a transistor Q2, a capacitor C3, a capacitor C4, a resistor R1, a transmission line TL6 and a transmission line TL7; The second oscillator core comprises a transistor Q3, a transistor Q4, a capacitor C5, a capacitor C6, a capacitor C7, a resistor R2, a transmission line TL8 and a transmission line TL9; The node V E1 、V E2 is used as a connecting node of the dual-core in-phase coupled oscillator core, the two-bit switched capacitor bank and the linearization variable capacitor bank, and ports OUT1, OUT2, OUT3 and OUT4 are used as four output ends of the dual-core in-phase coupled oscillator core to be connected with the output buffer; The node V E1 is connected to one end of the transmission line TL6, the emitter of the transistor Q1, one end of the capacitor C2, one end of the transmission line TL9, one end of the capacitor C6, and the emitter of the transistor Q4, respectively; The node V E2 is connected to one end of the capacitor C3, the emitter of the transistor Q2, one end of the transmission line TL7, one end of the capacitor C5, the emitter of the transistor Q3, and one end of the transmission line TL8, respectively; The other end of the capacitor C2 is connected with the other end of the capacitor C3, the other end of the transmission line TL6, the other end of the transmission line TL7, one end of the resistor R1 and one end of the capacitor C4 are connected, and the other end of the resistor R1 and the other end of the capacitor C4 are grounded; The other end of the capacitor C5 is connected with the other end of the capacitor C6, the other end of the transmission line TL8, the other end of the transmission line TL9, one end of the resistor R2 and one end of the capacitor C7 are connected, and the other end of the resistor R2 and the other end of the capacitor C7 are grounded; The collector of the transistor Q1, the collector of the transistor Q2, one end of the transmission line TL1 and one end of the transmission line TL2 are connected, the other end of the transmission line TL1 is connected with a power supply voltage V CC1 , the base of the transistor Q1 and the base of the transistor Q2 are connected with the inductor L2, the inductor L2 is coupled with the inductor L1, and two ends of the inductor L1 are respectively used as the port OUT1 and the port OUT2; The collector of the transistor Q3, the collector of the transistor Q4, one end of the transmission line TL3 and one end of the transmission line TL4 are connected, the other end of the transmission line TL4 is connected with the power supply voltage V CC1 , the inductor L4 is connected between the base of the transistor Q3 and the base of the transistor Q4, the inductor L4 is coupled with the inductor L3, two ends of the inductor L3 are respectively used as a port OUT3 and a port OUT4, and the center taps of the inductor L2 and the inductor L4 are connected with the bias voltage V B1 ; The other end of the transmission line TL2, the other end of the transmission line TL3 and one end of the transmission line TL5 are connected, the other end of the transmission line TL5 is connected with one end of the capacitor C1, and the other end of the capacitor C1 is used as the port OUT5.
4. The W-band low-noise voltage controlled oscillator based on transformer resonant cavity and harmonic extraction of claim 1, wherein the binary state combination of the switch control voltage V S1 and the switch control voltage V S2 comprises: 1) A state in which V S1 is low and V S2 is low; 2) A state in which V S1 is low and V S2 is high; 3) A state in which V S1 is high and V S2 is low; 4) A state in which V S1 is high and V S2 is high; wherein each binary state combination corresponds to a subband.
5. The W-band low-noise voltage-controlled oscillator based on transformer resonant cavity and harmonic extraction of claim 1, wherein the two-bit switched capacitor group comprises a transistor Q5, a transistor Q6, a transistor Q7, a transistor Q8, a transistor Q9, a transistor Q10, a transistor Q11, a transistor Q12, a capacitor C8, a capacitor C9, a capacitor C10, a capacitor C11, a capacitor C12, a capacitor C13, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, and a resistor R12, The switch control voltage V S1 enters one end of the resistor R4 and one end of the resistor R9 respectively; The switch control voltage V S2 enters one end of the resistor R5 and one end of the resistor R10 respectively; The other end of the resistor R4 is respectively connected with the base electrode of the transistor Q5 and the base electrode of the transistor Q6, the emitter electrode of the transistor Q5 and the collector electrode of the transistor Q6 are respectively connected with one end of the resistor R7, one end of the capacitor C10, the emitter electrode of the transistor Q8 and the collector electrode of the transistor Q7, the other end of the resistor R7 and the other end of the capacitor C10 are respectively grounded, the collector electrode of the transistor Q5 and the emitter electrode of the transistor Q6 are respectively connected with one end of the resistor R3 and one end of the capacitor C8, and the other end of the resistor R3 is grounded; The other end of the resistor R5 is respectively connected with the base electrode of the transistor Q7 and the base electrode of the transistor Q8, the collector electrode of the transistor Q8 and the emitter electrode of the transistor Q7 are both connected with one end of the resistor R6 and one end of the capacitor C9, and the other end of the resistor R6 is grounded; The other end of the resistor R9 is respectively connected with the base electrode of the transistor Q9 and the base electrode of the transistor Q10, the emitter electrode of the transistor Q9 and the collector electrode of the transistor Q10 are respectively connected with one end of the resistor R12, one end of the capacitor C13, the emitter electrode of the transistor Q12 and the collector electrode of the transistor Q11, the other end of the resistor R12 and the other end of the capacitor C13 are respectively grounded, the collector electrode of the transistor Q9 and the emitter electrode of the transistor Q10 are respectively connected with one end of the resistor R8 and one end of the capacitor C11, and the other end of the resistor R8 is grounded; The other end of the resistor R10 is respectively connected with the base electrode of the transistor Q11 and the base electrode of the transistor Q12, the collector electrode of the transistor Q12 and the emitter electrode of the transistor Q11 are respectively connected with one end of the resistor R11 and one end of the capacitor C12, the other end of the resistor R11 is grounded, and the other end of the capacitor C11 and the other end of the capacitor C12 are respectively connected with a node V E2 of the dual-core in-phase coupling oscillator core.
6. The W-band low-noise voltage controlled oscillator based on transformer resonant cavity and harmonic extraction of claim 1, wherein the linearized variable capacitance set comprises a capacitor C14, a capacitor C15, a capacitor C16, a capacitor C17, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a varactor VARC1, and a varactor VARC2, The direct-current control voltage signal V T enters the control end of the variable capacitance tube VARC1 and the control end of the variable capacitance tube VARC2 respectively; one end of the varactor VARC1 is respectively connected with one end of the resistor R13 and one end of the capacitor C14, and the other end of the varactor VARC1 is respectively connected with one end of the resistor R14 and one end of the capacitor C15, wherein the other end of the resistor R13 and the other end of the resistor R14 are both connected with a bias voltage V B2 , the other end of the capacitor C14 is connected with a node V E1 of the dual-core in-phase coupled oscillator core, and the other end of the capacitor C15 is connected with a node V E2 of the dual-core in-phase coupled oscillator core; One end of the varactor VARC2 is respectively connected with one end of the resistor R15 and one end of the capacitor C16, and the other end of the varactor VARC2 is respectively connected with one end of the resistor R16 and one end of the capacitor C17, wherein the other end of the resistor R15 and the other end of the resistor R16 are both connected with a bias voltage V B3 ; the other end of the capacitor C16 is connected with the other end of the capacitor C14, and the other end of the capacitor C17 is connected with the other end of the capacitor C15.
7. The W-band low-noise voltage controlled oscillator according to claim 1, wherein the output buffer comprises a transistor Q13, a transistor Q14, a transistor Q15, a transistor Q16, a transistor Q17, a transistor Q18, a transistor Q19, a transistor Q20, a transistor Q21, a capacitor C18, a capacitor C19, a capacitor C20, a capacitor C21, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, and a resistor R26, Ports IN1, IN2, IN3, IN4 are respectively connected with ports OUT1, OUT2, OUT3, and OUT4 of the dual-core IN-phase coupled oscillator core; One end of the capacitor C18 is used as the port IN1, and the other end of the capacitor C18 is respectively connected with one end of the resistor R17 and the base electrode of the transistor Q13, and one end of the capacitor C19 is used as the port IN2, and the other end of the capacitor C19 is respectively connected with one end of the resistor R18 and the base electrode of the transistor Q15; The emitter of the transistor Q13 is connected with the collector of the transistor Q14 and the tap between the emitter and the collector is used as the positive terminal for outputting the fundamental oscillation signal LO 2 , and the emitter of the transistor Q15 is connected with the collector of the transistor Q16 and the tap between the emitter and the collector is used as the negative terminal for outputting the fundamental oscillation signal LO 2 ; The emitter of the transistor Q14 is connected with one end of the resistor R19, the emitter of the transistor Q16 is connected with one end of the resistor R20, the base of the transistor Q14, the base of the transistor Q16, the base of the transistor Q18, the base of the transistor Q20 and the base of the transistor Q21 are connected, the base and the collector of the transistor Q21 are connected, and the collector of the transistor Q21 is connected with one end of the resistor R26; An emitter of the transistor Q21 is connected to one end of the resistor R25; one end of the capacitor C20 is used as a port IN3, and the other end of the capacitor C20 is respectively connected with one end of the resistor R21 and the base electrode of the transistor Q17, one end of the capacitor C21 is used as a port IN4, and the other end of the capacitor C21 is respectively connected with one end of the resistor R22 and the base electrode of the transistor Q19; The emitter of the transistor Q17 is connected with the collector of the transistor Q18 and the tap between the emitter and the collector is used as the positive terminal for outputting the fundamental oscillation signal LO 3 , and the emitter of the transistor Q19 is connected with the collector of the transistor Q20 and the tap between the emitter and the collector is used as the negative terminal for outputting the fundamental oscillation signal LO 3 ; An emitter of the transistor Q18 is connected to one end of the resistor R23, and an emitter of the transistor Q20 is connected to one end of the resistor R24; The other end of the resistor R26, the other end of the resistor R17, the other end of the resistor R18, the collector of the transistor Q13, the collector of the transistor Q15, the other end of the resistor R21, the other end of the resistor R22, the collector of the transistor Q17 and the collector of the transistor Q19 are connected with a power supply voltage V CC2 ; The other end of the resistor R25, the other end of the resistor R19, the other end of the resistor R20, the other end of the resistor R23 and the other end of the resistor R24 are all grounded.
8. The W-band low-noise voltage-controlled oscillator based on transformer resonant cavity and harmonic extraction of claim 1, wherein the output frequency range of the target oscillating signal LO 1 is 99GHz to 106GHz, and the phase noise at 1MHz frequency offset in the full frequency band is lower than 95DBc/Hz, the output power is higher than 1.2dBm。
9. The W-band low-noise voltage controlled oscillator based on transformer resonant cavity and harmonic extraction of claim 3, wherein the lengths of the transmission lines TL1 and TL4 are configured to exhibit quarter-wavelength shorting line characteristics at a target second harmonic frequency to provide high impedance of the second harmonic at the collector common mode nodes of the transistors Q1-Q2 and Q3-Q4.
10. The W-band low-noise voltage controlled oscillator based on transformer resonant cavity and harmonic extraction of any one of claims 3 to 7, wherein the W-band low-noise voltage controlled oscillator is obtained using SiGe BiCMOS technology.

Description

W-band low-noise voltage-controlled oscillator based on transformer resonant cavity and harmonic extraction Technical Field The invention belongs to the technical field of millimeter wave integrated circuits, and particularly relates to a W-band low-noise voltage-controlled oscillator based on transformer resonant cavity and harmonic extraction. Background Millimeter wave frequency bands, particularly W-band (75-110 GHz), have become key carriers for next-generation high-speed communication, high-resolution radar and imaging systems by virtue of extremely wide available bandwidths. The core of the frequency synthesizer is a voltage-controlled oscillator with low phase noise and wide tuning range. However, conventional design approaches face significant challenges when the oscillator operating frequency is increased to the W-band. First, oscillators based on cross-coupled structures have difficulty achieving excellent phase noise in the W-band, limited by the switching performance and limited output swing of CMOS transistors at very high frequencies. Secondly, although the colpitts structure can work at higher frequency, the common collector load inductance of the colpitts structure can introduce obvious parasitic effect, so that the maximum oscillation amplitude is limited, the breakdown risk of a transistor is increased, and the further optimization of phase noise is restricted. Furthermore, direct use of varactor tuning to achieve a wide tuning range can result in excessive tuning gain, making the oscillation frequency extremely sensitive to control voltage noise, exacerbating in-band phase noise, and exacerbating reference spurs when applied to a phase locked loop. In order to overcome the above problems, the prior art introduces a switched capacitor array for frequency band division to reduce tuning gain, and attempts to adopt a harmonic extraction technology to reduce the core oscillation frequency and improve the quality factor of passive devices. However, in the W-band, the effective implementation of these techniques is limited by the inherent nature of the process. For example, the turn-off performance of the MOS switch in the conventional silicon-based CMOS process is drastically degraded in the W-band, resulting in a low quality factor of the switched capacitor array, a drastic increase in insertion loss, and no effective frequency band division and noise optimization can be achieved. Therefore, how to implement a voltage-controlled oscillator with low phase noise, high output power, wide tuning range and low tuning gain in the W-band becomes a key technical problem to be solved in the current millimeter wave integrated circuit design field. Disclosure of Invention In order to solve the problems in the prior art, the invention provides a W-band low-noise voltage-controlled oscillator based on transformer resonant cavity and harmonic extraction. The technical problems to be solved by the invention are realized by the following technical scheme: the invention provides a W-band low-noise voltage-controlled oscillator based on transformer resonant cavity and harmonic extraction, which comprises a dual-core in-phase coupling oscillator core, a two-bit switch capacitor group, a linearization variable capacitor group and an output buffer, wherein the dual-core in-phase coupling oscillator core is connected with the output buffer; The dual-core in-phase coupled oscillator core comprises a transformer resonant cavity and a harmonic extraction network integrated in the transformer resonant cavity, wherein the transformer resonant cavity is used for generating a fundamental wave oscillating signal based on the discrete capacitance value and the fine tuning capacitance value and coupling and outputting the fundamental wave oscillating signal to the output buffer, the harmonic extraction network is used for extracting second harmonic from the fundamental wave oscillating signal and performing power synthesis to generate and output a W-band target oscillating signal LO 1, the two-bit switch capacitance group is used for responding to binary state combination of a switch control voltage V S1 and a switch control voltage V S2 and providing corresponding discrete capacitance values for the dual-core in-phase coupled oscillator core so as to divide the total tuning range of the oscillating frequency output by the dual-core in-phase coupled oscillator core into a plurality of mutually overlapped discrete sub-bands and realize step tuning of the oscillating frequency, the linearization variable capacitance group is used for responding to a continuously variable direct current control voltage signal V T and outputting a fine tuning capacitance value used for determining the oscillating frequency in the two-bit switch capacitance group, and performing differential buffer mode on the oscillating signal LO 2 and the oscillating signal is outputted by the dual-core in the dual-phase coupled oscillator core. Compared with