A low phase noise class-d voltage controlled oscillator based on wideband harmonic shaping technique

Abstract

A low phase noise class-D voltage controlled oscillator based on wideband harmonic shaping technology, comprising a head resonant unit, an LC resonant unit composed of a first inductive unit, a second inductive unit and a first capacitive unit, a negative resistance unit, a variable capacitive unit, an array capacitive unit and an output unit, the output end of the head resonant unit is connected with one end of the first inductive unit, the other end of the first inductive unit is connected with one end of the negative resistance unit, the other end of the negative resistance unit is connected with the first capacitive unit, the first capacitive unit is connected with the variable capacitive unit, the variable capacitive unit is connected with one end of the array capacitive unit, the other end of the array capacitive unit is connected with one end of the second inductive unit, the other end of the second inductive unit is grounded, two input ends of the output unit are connected with the variable capacitive unit, and two output ends are used as output ports of the voltage controlled oscillator.

Description

Technical Field

[0001] This invention pertains to voltage-controlled oscillators, specifically a low-phase-noise Class D voltage-controlled oscillator based on broadband harmonic shaping technology. Background Technology

[0002] In communication systems, the voltage-controlled oscillator (VCO) is a core component of the phase-locked loop (PLL), and its performance is crucial to the overall efficiency of the wireless transceiver system. Oscillators must meet various performance requirements during design, such as low phase noise, high quality factor, wide tuning range, low power consumption, and small area. Design techniques are employed to ensure that the oscillator generates a stable oscillation waveform while meeting these performance specifications.

[0003] Class D voltage-controlled oscillators are widely used in advanced CMOS processes, achieving large output swings in the GHz band, and also feature small chip area and simple design. Traditional Class D voltage-controlled oscillator circuits include... Figure 1 As shown. The inductor L adopts a center-tapped structure, with the tap connected to the power supply V. DD The other two ends are connected in parallel with capacitor C, and NMOS transistor M D1 With NMOS transistor M D2 These two switching transistors form a cross-coupled pair. The drains of the two NMOS transistors are connected in parallel with capacitor C, and their sources are connected to ground. Inductor L and capacitor C form a parallel resonant network. Due to imperfections in the actual components, the LC resonant structure will have additional resistance, which will continuously consume the energy of the resonant network, causing the waveform amplitude to gradually decay. The cross-coupled pair is composed of two NMOS transistors. As an active device, its equivalent resistance is -2 / g. m g m To reduce the transconductance of an NMOS transistor, using a larger NMOS transistor can lower g. m This increases the equivalent negative resistance, compensating for the energy loss of the resonant circuit and ensuring the start-up of the Class D voltage-controlled oscillator. During circuit oscillation, using advanced CMOS technology to provide switches with lower on-resistance and parasitic capacitance, current can transfer from one switch to another in a very short time. The two switches alternately turn on and off, outputting two inverted waveforms. This structure consists of only one LC resonant circuit and two cross-coupled NMOS transistors, making it simple to design and providing a large output swing. However, traditional Class D voltage-controlled oscillators have the following drawbacks:

[0004] First, it has low harmonic impedance. In traditional Class D voltage-controlled oscillators, the parasitic capacitance C between the gate and substrate of the two cross-coupled NMOS transistors is low. gs This will reduce the value of the common-mode impedance at twice the resonant frequency, thus reducing the harmonic suppression effect.

[0005] Secondly, the harmonic impedance bandwidth is narrow. The common-mode impedance of a traditional Class D voltage-controlled oscillator is a narrow-band impedance that decays rapidly near twice the resonant frequency. When the resonant frequency is changed using a variable capacitor, the common-mode impedance decays rapidly, leading to an increase in the second harmonic component and worsening the phase noise. Therefore, manual tuning is required to make the common-mode impedance at its maximum value.

[0006] Third, the frequency adjustment range is small. Traditional Class D voltage-controlled oscillators only use a variable capacitor C to adjust the resonant frequency of the LC resonant network. However, the capacitance value of the variable capacitor is not large, and due to the influence of parallel parasitic capacitance, the proportion of the variable capacitor in the total capacitance is reduced. Therefore, the actual tunable range of the resonant frequency becomes narrower.

[0007] Fourth, it is sensitive to flicker noise up-conversion. Traditional Class D voltage-controlled oscillators use cross-coupled pairs composed of NMOS transistors, and its inductor L is a single-turn inductor with a small inductance and high quality factor, at 1 / f 3 The large phase noise corner frequency at certain points makes Class D voltage-controlled oscillators highly sensitive to flicker noise upconversion. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of traditional Class D voltage-controlled oscillators and provide a low-phase-noise Class D voltage-controlled oscillator based on broadband harmonic shaping technology. While ensuring the characteristics of high output voltage swing and small chip area, the oscillator's tuning range is widened, and automatic harmonic tuning is achieved within a certain range, thereby increasing the output voltage swing and reducing phase noise.

[0009] The technical solution to achieve the purpose of this invention is as follows: a low phase noise Class D voltage-controlled oscillator based on broadband harmonic shaping technology, comprising a head resonant unit, an LC resonant unit composed of a first inductor unit, a second inductor unit, and a first capacitor unit, a negative resistance unit, a variable capacitor unit, an array capacitor unit, and an output unit. The output terminal of the head resonant unit is connected to one end of the first inductor unit, the other end of the first inductor unit is connected to one end of the negative resistance unit, the other end of the negative resistance unit is connected to the first capacitor unit, the first capacitor unit is also connected to the variable capacitor unit, the variable capacitor unit is also connected to one end of the array capacitor unit, the other end of the array capacitor unit is connected to one end of the second inductor unit, the other end of the second inductor unit is grounded, the two input terminals of the output unit are connected to the variable capacitor unit, and the two output terminals serve as the output ports of the voltage-controlled oscillator.

[0010] Preferably, the head resonant unit includes a capacitor C1, an inductor L1, and an inductor L2. One end of inductor L1 is connected to one end of capacitor C1, and the other end of inductor L1 is connected to one end of inductor L2. The other end of capacitor C1 is connected to a power supply V. DDThe other end of inductor L1 forms the output port, and the other end of inductor L2 is connected to the power supply V. DD One end of inductor L2 forms the output port, and there is a coupling coefficient k between inductor L1 and inductor L2. m .

[0011] Preferably, the head resonant unit resonates at the second harmonic frequency of the voltage-controlled oscillator.

[0012] Preferably, the first inductor unit includes an inductor L. d1 Inductor L d2 The second inductor unit includes inductor L s1 Inductor L s2 The first capacitor unit includes capacitor C m1 Capacitor C m2 The inductor L d1 One end, inductor L d2 One end of each is connected to the output port of the head resonant unit, and the inductor L d1 The other end, inductor L d2 The other end serves as the output port of the first inductor unit; the capacitor C m1 One end is connected to capacitor C m2 One end of the capacitor C is connected to the capacitor C. m1 The other end, capacitor C m2 The other end also serves as both ends of the first capacitor unit; the inductor L s1 One end, inductor L s2 One end of each is used as one end of the second inductor unit, and the inductor L s1 The other end, inductor L s2 The other end of each serves as the other end of the second inductor unit.

[0013] Preferably, the negative resistance unit includes PMOS transistor M1, PMOS transistor M2, and inductor L. f1 Inductor L f2 Capacitor C f1 Capacitor C f2 The source of PMOS transistor M1 is connected to the inductor L. d1 At the other end, the gate of PMOS transistor M1 is connected to capacitor C. m1 At the other end, the drain of PMOS transistor M1 is connected to the gate of PMOS transistor M2; the source of PMOS transistor M2 is connected to inductor L. d2 At the other end, the drain of PMOS transistor M2 is connected to capacitor C. m2 At the other end, the drain of PMOS transistor M2 is connected to the gate of PMOS transistor M1, and the gate of PMOS transistor M2 is connected to the drain of PMOS transistor M1. The substrates of both PMOS transistors M1 and M2 are connected to the power supply V. DD Inductor Lf1 With capacitor C f1 The circuit is connected in parallel, with one end connected to the drain of PMOS transistor M1 and the other end grounded; inductor L f2 With capacitor C f2 Connected in parallel, one end is connected to the drain of PMOS transistor M2, and the other end is grounded.

[0014] Preferably, the variable capacitor unit includes capacitors C connected in sequence. m3 Variable capacitor C v1 Capacitor C m4 Variable capacitor C v2 Capacitor C m3 Not with variable capacitor C v1 One end of the connection serves as a connection terminal for the variable capacitor unit, and the capacitor C m4 Not with variable capacitor C v2 One end of the connection serves as the other connection end of the variable capacitor unit.

[0015] Compared with the prior art, the significant advantages of this invention are:

[0016] (1) High harmonic impedance. The head resonant unit of the present invention can increase the impedance value of the second harmonic and suppress the influence of the second harmonic component on the resonant circuit, thereby suppressing the phase noise degradation of the voltage-controlled oscillator.

[0017] (2) Wide harmonic impedance bandwidth. The head resonant unit of the present invention can keep the phase of the second harmonic at about 0 degrees over a wide frequency band and the phase of the third harmonic at about -90 degrees over a wide frequency band. Therefore, the common mode impedance is near the maximum value over a wide frequency band, and there is no need to manually tune the common mode impedance to the maximum value.

[0018] (3) Wide tuning range and high tuning accuracy. Both the variable capacitor unit and the array capacitor unit in this invention can adjust the resonant frequency of the LC resonant unit. The array capacitor unit allows for coarse frequency tuning, while the variable capacitor unit allows for fine frequency tuning. The voltage-controlled oscillator achieves a precise tuning range from 6 to 7.5 GHz (see...). Figure 5 ).

[0019] (4) Insensitive to flicker noise upconversion. The present invention uses PMOS active devices as the cross-coupled pairs of the voltage-controlled oscillator, which has advantages over bipolar devices in the common-mode secondary resonance resonant circuit. At the same time, the load applied to the resonant circuit by the PMOS device when the transistor is pushed in is lower. The PMOS transistor has a device area that is 2 to 3 times larger than that of the NMOS transistor with the same driving capability, and has lower flicker noise. Therefore, the use of PMOS active devices is insensitive to flicker noise upconversion.

[0020] (5) Low phase noise. The inductor L in the LC resonant unit of this invention... dInductor L s The coupling coefficient k1 between them forms a periodic time-varying inductor, which, together with the positive feedback impedance of higher harmonics, increases the output swing to 5.5V. DD This also increases the common-mode impedance of the second harmonic, which reduces phase noise (see...). Figure 6 ).

[0021] (6) Good output stability. The output unit of this invention is a buffer amplifier composed of two two-stage CMOS inverters. The first stage of the amplifier can increase the input impedance and suppress the influence of the amplifier on phase noise, while the second stage is used to drive a 50-ohm load. The K-stability factor is greater than 1 throughout the entire frequency band, and even at the lowest point, the K-stability factor is 6. Therefore, the buffer amplifier will not cause output waveform distortion due to its own instability.

[0022] (7) Large output swing. The inductor L in the LC resonant unit of this invention... d Inductor L s The coupling coefficient k1 between them forms a periodic time-varying inductor, which increases the amplitude enhancement factor to 2. Combined with the positive feedback impedance of higher harmonics, this increases the peak voltage of the voltage-controlled oscillator to 4.5V, and the output voltage swing can reach 5.5V. DD The swing amplitude is much larger than that of a traditional Class D voltage-controlled oscillator. Attached Figure Description

[0023] Figure 1 The circuit schematic of a traditional Class D voltage-controlled oscillator.

[0024] Figure 2 This is a circuit block diagram of the voltage-controlled oscillator of the present invention.

[0025] Figure 3 This is the circuit schematic diagram of the voltage-controlled oscillator of the present invention.

[0026] Figure 4 This is a schematic diagram of the half-cycle current flow direction of the LC resonant unit of the present invention.

[0027] Figure 5 This refers to the frequency range that the voltage-controlled oscillator of this invention can achieve under different tuning voltages and different array capacitors.

[0028] Figure 6 This refers to the phase noise range of the voltage-controlled oscillator of the present invention at different resonant frequencies at frequency offsets of 100kHz and 1MHz.

[0029] Figure 7 This is a schematic diagram of a switched capacitor.

[0030] Figure 8 This is a schematic diagram of a two-stage inverter. Detailed Implementation

[0031] like Figure 2 As shown, a low-phase-noise Class D voltage-controlled oscillator based on broadband harmonic shaping technology includes a head resonant unit (1), an LC resonant unit (2) composed of a first inductor unit (2.1), a second inductor unit (2.3), and a first capacitor unit (2.2), a negative resistance unit (3), a variable capacitor unit (4), an array capacitor unit (5), and an output unit (6). The output terminal of the head resonant unit (1) is connected to one end of the first inductor unit (2.1), and the other end of the first inductor unit (2.1) is connected to the negative resistance unit (3). One end is connected to the negative resistance unit (3), and the other end is connected to the first capacitor unit (2.2). The first capacitor unit (2.2) is also connected to the variable capacitor unit (4). The variable capacitor unit (4) is also connected to one end of the array capacitor unit (5). The other end of the array capacitor unit (5) is connected to one end of the second inductor unit (2.3). The other end of the second inductor unit (2.3) is grounded. The two input ends of the output unit (6) are connected to the variable capacitor unit (4). The two output ends serve as the output ports of the voltage-controlled oscillator. In this invention, the head resonant unit (1) can improve the common-mode impedance of the voltage-controlled oscillator; the LC resonant unit (2) includes a capacitor-inductor parallel resonant network to generate an oscillation signal; the negative resistance unit (3) provides a negative resistance value for the resonant circuit to compensate for the energy loss of the resonant circuit and ensure that the voltage-controlled oscillator can start oscillating; the variable capacitor unit (4) and the array capacitor unit (5) provide a capacitor with a variable capacitance value for the resonant circuit, so that the resonant frequency can be adjusted within a certain range, wherein the array capacitor unit (5) coarsely adjusts the capacitance value and the variable capacitor unit (4) finely adjusts the capacitance value.

[0032] like Figure 3 As shown, in a further embodiment, the head resonant unit (1) includes a capacitor C1, an inductor L1, and an inductor L2. One end of the inductor L1 is connected to one end of the capacitor C1, and the other end of the inductor L1 is connected to one end of the inductor L2. The other end of the capacitor C1 is connected to the power supply V. DD The other end of inductor L1 forms the output port, and the other end of inductor L2 is connected to the power supply V. DD One end of inductor L2 forms the output port, and there is a coupling coefficient k between inductor L1 and inductor L2. m The head resonant unit (1) resonates at the second harmonic frequency of the voltage-controlled oscillator.

[0033] like Figure 3 As shown, in a further embodiment, the first inductor unit (2.1) includes an inductor L. d1 Inductor L d2 The second inductor unit (2.3) includes inductor L s1Inductor L s2 The first capacitor unit (2.2) includes capacitor C. m1 Capacitor C m2 The inductor L d1 One end, inductor L d2 One end of each is connected to the output port of the head resonant unit (1), and the inductor L d1 The other end, inductor L d2 The other end serves as the output port of the first inductor unit (2.1); the capacitor C m1 One end is connected to capacitor C m2 One end of the capacitor C is connected to the capacitor C. m1 The other end, capacitor C m2 The other end also serves as both ends of the first capacitor unit (2.2); the inductor L s1 One end, inductor L s2 One end of each serves as one end of the second inductor unit (2.3), wherein the inductor L s1 The other end, inductor L s2 The other end of each serves as the other end of the second inductor unit (2.3).

[0034] The capacitor C1, inductor L1, and inductor L2 of the head resonant unit (1) constitute a common-mode extended resonant circuit. The connection point of inductor L1 and inductor L2 is equivalent to a virtual ground for the differential-mode signal, so the differential-mode impedance and common-mode impedance can be considered separately. Inductor L1 and inductor L2 are connected to the LC resonant unit (2) by inductor L... d1 Inductor L d2 Inductor L s1 Inductor L s2 The 1:2 transformers together form a composite inductor with a resonant point at twice the resonant frequency. Furthermore, their respective resonant circuits are out of phase, resulting in a common-mode impedance with approximately zero phase in the frequency range near twice the resonant frequency. This allows the voltage-controlled oscillator (VCO) to suppress the effects of the second harmonic and achieve automatic tuning of the second harmonic within a certain range, as the common-mode impedance and phase change relatively little near the second harmonic.

[0035] The LC resonant unit (2) includes a first inductor unit (2.1), a second inductor unit (2.3), and a first capacitor unit (2.2), wherein the first inductor unit (2.1) includes an inductor L d1 Inductor L d2 The second inductor unit (2.3) includes inductor L s1 Inductor L s2 Together, they form a 1:2 transformer. The first capacitor unit (2.2) includes capacitor C. m1 Capacitor C m2The LC resonant unit (2) is the resonant circuit of the voltage-controlled oscillator. Capacitors Cm1 and Cm2 are both 400pF, equivalent to being connected in parallel with the composite inductor. This causes the third-mode resonant frequency to be lower than three times the resonant frequency of the voltage-controlled oscillator. This is because the parallel capacitor increases the total capacitance, reducing the capacitive reactance and thus decreasing the total impedance of the resonant circuit, resulting in a lower resonant frequency. The phase of the differential-mode impedance near the third resonant frequency remains around -90 degrees, equivalent to a capacitor. This makes the effect of the third harmonic on the resonant circuit equivalent to only one capacitor, and the phase change near the third resonant frequency is very small. Therefore, the voltage-controlled oscillator can achieve automatic tuning of the third harmonic. Inductor L d The value is 300 pH, and the inductance is L. s The value of is 732 pH, the coupling coefficient k1 is 0.78, and the coupling coefficient is... The value of .

[0036] like Figure 3 As shown, in a further embodiment, the negative resistance unit (3) includes PMOS transistor M1, PMOS transistor M2, and inductor L. f1 Inductor L f2 Capacitor C f1 Capacitor C f2 The source of PMOS transistor M1 is connected to the inductor L. d1 At the other end, the gate of PMOS transistor M1 is connected to capacitor C. m1 At the other end, the drain of PMOS transistor M1 is connected to the gate of PMOS transistor M2; the source of PMOS transistor M2 is connected to inductor L. d2 At the other end, the drain of PMOS transistor M2 is connected to capacitor C. m2 At the other end, the drain of PMOS transistor M2 is connected to the gate of PMOS transistor M1, and the gate of PMOS transistor M2 is connected to the drain of PMOS transistor M1. The substrates of both PMOS transistors M1 and M2 are connected to the power supply V. DD Inductor L f1 With capacitor C f1 The circuit is connected in parallel, with one end connected to the drain of PMOS transistor M1 and the other end grounded; inductor L f2 With capacitor C f2 Connected in parallel, one end is connected to the drain of PMOS transistor M2, and the other end is grounded.

[0037] The cross-coupled pair formed by PMOS transistors M1 and M2 in the negative resistance unit (3) not only compensates for the energy consumption of the resonant circuit, but also acts as a switch that is constantly turned on and off. One oscillation cycle can be divided into two half-cycles. The T1 cycle is when PMOS transistor M1 is on and PMOS transistor M2 is off, and the T2 cycle is when PMOS transistor M2 is on and PMOS transistor M1 is off. During the T1 cycle, due to the coupling inductance L sThe existence of equivalent inductance L T1 The value is L d -M; During cycle T2, due to the presence of the DC blocking capacitor C, the equivalent inductance L T2 The value is L d Amplitude enhancement factor L T2 / L T1 The value of is 2. This significantly increases the output voltage swing, thus improving phase noise. For PMOS transistors M1 and M2, which exhibit nonlinear behavior, the harmonics of the gate and drain voltages alter the harmonics of the drain current. Inductor L f1 Capacitor C f1 The drain load impedance and inductance L of PMOS transistor M1 are... f2 Capacitor C f2 The drain load impedance of PMOS transistor M2. When the generated second harmonic current flows through the drain load impedance of PMOS transistor M1, a second harmonic voltage is generated at the drain. This voltage induces the fundamental current again through the nonlinearity of the PMOS transistor. When the enhanced drain current at the resonant frequency flows through the drain load impedance, it can further increase the drain voltage at the resonant frequency, thus forming positive feedback. At the same time, the load impedance oscillates at the frequency of the second harmonic, which can increase the common-mode impedance. Finally, it can increase the output voltage swing at the resonant frequency and improve the phase noise of the voltage-controlled oscillator.

[0038] like Figure 3 As shown, in a further embodiment, the variable capacitor unit (4) includes capacitors C connected in sequence. m3 Variable capacitor C v1 Capacitor C m4 Variable capacitor C v2 Capacitor C m3 Not with variable capacitor C v1 One end of the connection serves as a connection terminal for the variable capacitor unit (4), and the capacitor C m4 Not with variable capacitor C v2 One end of the connection serves as the other connection end of the variable capacitor unit (4).

[0039] like Figure 7 As shown, in a further embodiment, the array capacitor unit (5) is provided with a 5-bit switched capacitor array, and each switched capacitor is provided with an NMOS transistor M. C1 Capacitor C C1 Capacitor C C2 Resistance R C1 Resistance R C2 , by PMOS transistor M C2 and NMOS transistor M C3 The inverter is constructed; the output unit (6) is equipped with two two-stage inverters, each of which is equipped with a capacitor C.B1 Capacitor C B2 Capacitor C B3 Resistance R B1 Resistance R B2 PMOS transistor M B1 and NMOS transistor M B2 The inverter and PMOS transistor M are constructed B3 and NMOS transistor M B4 An inverter is constructed from these components.

[0040] Both the variable capacitor unit (4) and the array capacitor unit (5) are used to tune the resonant frequency of the voltage-controlled oscillator. The variable capacitor unit (4) is tuned by the tuning voltage V. tune Adjust the variable capacitor C v1 and variable capacitor C v2 The voltage drop is adjusted to obtain different capacitance values. Because the capacitance range of the variable capacitor unit (4) is much smaller than the total capacitance range of the array capacitor unit (5), it can be used to fine-tune the resonant frequency. The array capacitor unit (5) controls the switching voltage V of the five switching units. Bit Adjusting the capacitance connected to the resonant circuit can be used to coarsely tune the resonant frequency.

[0041] This invention employs CMOS technology and utilizes a periodic time-varying common-mode spread spectrum inductor to suppress high-order harmonic components generated by circuit nonlinearity, enabling automatic tuning within a certain frequency band. It also utilizes a periodic time-varying transformer to increase the swing amplitude of the voltage-controlled oscillator (VCO), and employs cross-coupled pairs formed by PMOS transistors and high-order harmonic positive feedback impedances to collectively improve the phase noise of the VCO and enhance its quality factor. Furthermore, it uses variable capacitors and array capacitors to broaden the tuning range of the VCO.

[0042] See Figure 4 As can be seen, the current loops of the LC resonant unit (2) of the present invention are in two half-cycles. (a) The figure shows that in the T1 cycle, the current flows into the ground through the switch. (b) The figure shows that the current is blocked by the capacitor C, forming an oscillation loop.

[0043] See Figure 5 As can be seen, the present invention is based on voltage V tune Under the control of [the system], the frequency of the voltage-controlled oscillator can be adjusted between 6 and 7.5 GHz. Because the slope of the voltage frequency line is very small, the voltage V [is low / high / low]. tune Variations between 0 and 1.2 volts only cause a change of about 2% in the oscillation frequency, demonstrating the wide tuning range and high tuning accuracy of the present invention.

[0044] See Figure 6As can be seen, the phase noise of the present invention ranges from -105.5 to -101.7 dBc / Hz at a frequency offset of 100 kHz from the carrier within the resonant frequency range of 6 to 7.5 GHz, and from -128 to -123 dBc / Hz at a frequency offset of 1 MHz from the carrier. The results show that the phase noise of the present invention is low.

[0045] The Class D oscillator designed in this invention consumes 26mW of power at a 1-volt supply voltage. In CMOS technology, this Class D oscillator uses common-mode resonant extended inductor technology, achieving a phase noise of -128 to -123 dBc / Hz at an operating frequency of 6–7.5 GHz and an offset frequency of 1 MHz, with a quality factor of 184–191.3 dBc / Hz. Considering the tuning range, the quality factor is 191–198.2 dBc / Hz. The chip core area is 0.1 mm². 2 The tuning range is 22.2%.

Claims

1. A low-phase-noise Class D voltage-controlled oscillator based on broadband harmonic shaping technology, characterized in that, The device includes a head resonant unit (1), an LC resonant unit (2) composed of a first inductor unit (2.1), a second inductor unit (2.3), and a first capacitor unit (2.2), a negative resistance unit (3), a variable capacitor unit (4), an array capacitor unit (5), and an output unit (6). The output terminal of the head resonant unit (1) is connected to one end of the first inductor unit (2.1), the other end of the first inductor unit (2.1) is connected to one end of the negative resistance unit (3), the other end of the negative resistance unit (3) is connected to the first capacitor unit (2.2), the first capacitor unit (2.2) is connected to the variable capacitor unit (4), the variable capacitor unit (4) is connected to one end of the array capacitor unit (5), the other end of the array capacitor unit (5) is connected to one end of the second inductor unit (2.3), the other end of the second inductor unit (2.3) is grounded, and the two input terminals of the output unit (6) are connected to the variable capacitor unit (4). The two output terminals serve as the output ports of the voltage-controlled oscillator. The head resonant unit (1) includes a capacitor C1, an inductor L1, and an inductor L2. One end of the inductor L1 is connected to one end of the capacitor C1, and the other end of the inductor L1 is connected to one end of the inductor L2. The other end of the capacitor C1 is connected to a power supply V. DD The other end of inductor L1 forms the output port, and the other end of inductor L2 is connected to the power supply V. DD One end of inductor L2 forms the output port, and there is a coupling coefficient k between inductor L1 and inductor L2. m The head resonant unit (1) resonates at the second harmonic frequency of the voltage-controlled oscillator; the first inductor unit (2.1) includes an inductor L. d1 Inductor L d2 The second inductor unit (2.3) includes inductor L s1 Inductor L s2 The first capacitor unit (2.2) includes capacitor C. m1 Capacitor C m2 The inductor L d1 One end, inductor L d2 One end of each is connected to the output port of the head resonant unit (1), and the inductor L d1 The other end, inductor L d2 The other end serves as the other end of the first inductor unit (2.1); the capacitor C m1 One end is connected to capacitor C m2 One end of the capacitor C is connected to the capacitor C. m1 The other end, capacitor C m2 The other end also serves as both ends of the first capacitor unit (2.2); the inductor L s1 One end, inductor L s2 One end of each serves as one end of the second inductor unit (2.3), wherein the inductor L s1 The other end, inductor L s2 The other end of each serves as the other end of the second inductor unit (2.3), with inductance L d1 With inductor L s1 There is a coupling coefficient k1, and an inductance L d2 With inductor L s2 There is a coupling coefficient k1 between them.

2. The low phase noise Class D voltage-controlled oscillator based on broadband harmonic shaping technology according to claim 1, characterized in that, The negative resistance unit (3) includes PMOS transistor M1, PMOS transistor M2, and inductor L. f1 Inductor L f2 Capacitor C f1 Capacitor C f2 The source of PMOS transistor M1 is connected to the inductor L. d1 At the other end, the drain of PMOS transistor M1 is connected to capacitor C. m1 At the other end, the drain of PMOS transistor M1 is connected to the gate of PMOS transistor M2; the source of PMOS transistor M2 is connected to inductor L. d2 At the other end, the drain of PMOS transistor M2 is connected to capacitor C. m2 At the other end, the drain of PMOS transistor M2 is connected to the gate of PMOS transistor M1, and the gate of PMOS transistor M2 is connected to the drain of PMOS transistor M1. The substrates of both PMOS transistors M1 and M2 are connected to the power supply V. DD Inductor L f1 With capacitor C f1 The circuit is connected in parallel, with one end connected to the drain of PMOS transistor M1 and the other end grounded; inductor L f2 With capacitor C f2 Connected in parallel, one end is connected to the drain of PMOS transistor M2, and the other end is grounded.

3. The low phase noise Class D voltage-controlled oscillator based on broadband harmonic shaping technology according to claim 2, characterized in that, The variable capacitor unit (4) includes capacitors C connected in sequence. m3 Variable capacitor C v1 Capacitor C m4 Variable capacitor C v2 Capacitor C m3 Not with variable capacitor C v1 The other end of the connection serves as a connection terminal for the variable capacitor unit (4), with capacitor C m4 Not with variable capacitor C v2 The other end of the connection serves as another connection point for the variable capacitor unit (4).

4. The low phase noise Class D voltage-controlled oscillator based on broadband harmonic shaping technology according to claim 3, characterized in that, The array capacitor unit (5) adopts a 5-bit switched capacitor array design, and each switched capacitor includes an NMOS transistor M. C1 Capacitor C C1 Capacitor C C2 Resistance R C1 Resistance R C2 And a first inverter, the first inverter being a PMOS transistor M C2 and NMOS transistor M C3 Composition; Capacitor C C1 One end is connected to the first port P1, and the other end is connected to the resistor R. C1 One end and NMOS transistor M C1 The source; capacitor C C2 One end is connected to the second port P2, and the other end is connected to resistor R. C2 One end and NMOS transistor M C1 Drain; Resistor R C1 With resistance R C2 The other end is connected to the output of the inverter, and the NMOS transistor M C1 The gate is connected to the input of the inverter; the switching control voltage V Bit Connect the input terminal of the inverter, and connect the output port P1 to the capacitor C of the variable capacitor unit (4). m3 At the other end, output port P2 is connected to capacitor C of variable capacitor unit (4). m4 The other end.

5. The low phase noise Class D voltage-controlled oscillator based on broadband harmonic shaping technology according to claim 3, characterized in that, The output unit (6) is composed of two identical two-stage inverters cascaded together, each two-stage inverter including a capacitor C. B1 Capacitor C B2 Capacitor C B3 Resistance R B1 Resistance R B2 The second inverter and the third inverter, the second inverter is composed of PMOS transistor M B1 and NMOS transistor M B2 The third inverter is composed of a PMOS transistor M. B3 and NMOS transistor M B4 Composition, capacitor C B1 One end is connected to the input port V in The other end is connected to the PMOS transistor M. B1 and NMOS transistor M B2 Gate and resistor R B1 One end, resistor R B1 The other end is connected to the bias voltage V BB Capacitor C B2 One end is connected to PMOS transistor M B1 and NMOS transistor M B2 The output of the second inverter is connected to the PMOS transistor M at the other end. B3 and NMOS transistor M B4 The input terminal of the third inverter is composed of resistor R. B2 One end is connected to PMOS transistor M B3 and NMOS transistor M B4 The input terminal of the third inverter is connected to the PMOS transistor M at the other end. B3 and NMOS transistor M B4 The output terminal of the third inverter, capacitor C B3 One end is connected to PMOS transistor M B3 and NMOS transistor M B4 The output of the third inverter is connected to the output port V. out The two input ports of the output unit (6) are respectively connected to the C of the variable capacitor unit (4). m3 The other end and C m4 At the other end, the two output ports constitute the output ports of the voltage-controlled oscillator.

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