CN106712719A - Orthogonal inductance-capacitance voltage-controlled oscillator with low power consumption and low phase noise - Google Patents

Abstract

The invention discloses a low-power-consumption and low-phase-noise quadrature inductance-capacitance voltage-controlled oscillator, comprising: two voltage-controlled oscillators VCO with the same structure, a diode-connected MOS transistor NM4 and a low-pass RC filter LPF; Among them, each VCO includes: an LC resonant network composed of an inductor and a distributed varactor structure circuit, an upper P lower N complementary negative resistance differential pair connected to the LC resonant network, and an upper P lower N complementary negative resistance differential pair. The series coupling tube and the tail current tube connected to the resistance differential pair tube; the series coupling tubes in the two VCOs are connected; the diode-connected MOS transistor NM4, the low-pass RC filter LPF, and the tail current tubes in the two VCOs are sequentially connected to form a current mirror. The above scheme has the characteristics of low power consumption, low phase noise, low phase error and high linear gain, and is suitable for phase-locked loop frequency synthesizers.

Description

Quadrature LC-VCO with Low Power Consumption and Low Phase Noise

technical field

The invention relates to the technical field of radio frequency integrated circuits, in particular to an orthogonal inductance-capacitance voltage-controlled oscillator with low power consumption and low phase noise.

Background technique

In recent years, with the rapid development of modern wireless communication technology and the rapid popularization of wireless portable devices, people's requirements for the mobility of electronic products have been limited by the development of battery capacity, and people have paid more and more attention to low power consumption design. At the same time, zero-IF and low-IF transceivers are increasingly used in wireless mobile communication systems due to their low power consumption, low cost, and high integration. Transceivers with zero-IF and low-IF structures require quadrature signals to achieve quadrature modulation and demodulation. Such a voltage-controlled oscillator (VCO) with low power consumption and low phase noise that can achieve accurate quadrature phase output becomes a transceiver key modules in .

At present, there are many ways to realize the quadrature phase output voltage-controlled oscillator. The first is a resistor-capacitor (RC) polyphase filter, whose phase shift is closely related to the RC value and is susceptible to process, voltage, and temperature (PVT) effects. At the same time, the RC polyphase filter circuit will cause signal attenuation and introduce resistance Thermal noise requires an additional amplifier stage to amplify the signal, which will also introduce a large system power consumption. The second is to use a ring oscillator, which is mostly used when the phase noise requirement is not high and the operating frequency is relatively low. According to the number of delay stages in the ring oscillator, each stage outputs a certain phase, the more stages, the more the number of output phases, and the greater the delay, the smaller the maximum output frequency generated. The third is the VCO two-frequency structure, which oscillates the VCO at twice the target frequency, and then directly divides the frequency by two to achieve quadrature. Since both the VCO and the frequency divider work at twice the target frequency, the power consumption increases , and the quadrature performance will be affected by the duty cycle of the VCO output waveform. The fourth method is to use a quadrature voltage-controlled oscillator (QVCO), directly coupling two identical LC-VCOs together, because its output has better phase noise performance and quadrature characteristics, QVCO has been widely used.

QVCO was first proposed by Rofougaran et al. in 1996. Its structure is shown in Figure 1. In this structure, the coupling tube and the switching tube are connected in parallel (called P-QVCO), and the width ratio between the coupling tube and the switching tube is defined. is the coupling strength. In a QVCO, various mismatches between two LC-VCOs will affect the quadrature signal amplitude and phase mismatch, where the amplitude mismatch can be adjusted by clipping through the output buffer, while the amplitude mismatch has no corresponding adjustment measures , so the phase error is an important indicator of QVCO. In P-QVCO, the phase error has a strong functional relationship with the coupling strength, resulting in a trade-off between phase error and phase noise, and the noise introduced by the parallel coupling tube will directly enter the resonant cavity, deteriorating the phase noise.

Andreani et al. proposed in 2002 a QVCO structure (called S-QVCO) in which a coupling tube and a switch tube are connected in series, and its structure is shown in FIG. 2 . Although the phase error in this scheme is only a weak function of the coupling strength, the phase error and phase noise performance can be optimized at the same time, but the power consumption and phase noise are still high, and further improvements are necessary.

Contents of the invention

The purpose of the present invention is to provide a low power consumption and low phase noise quadrature inductor-capacitor voltage-controlled oscillator, which has the characteristics of low power consumption, low phase noise, low phase error and high linear gain, and is suitable for phase-locked loop frequency in the synthesizer.

The purpose of the present invention is achieved through the following technical solutions:

A low-power-consumption and low-phase-noise quadrature inductor-capacitor voltage-controlled oscillator, comprising: two voltage-controlled oscillators VCO with the same structure, a diode-connected MOS transistor NM4, and a low-pass RC filter LPF;

Among them, each VCO includes: an LC resonant network composed of an inductor and a distributed varactor structure circuit, an upper P lower N complementary negative resistance differential pair connected to the LC resonant network, and an upper P lower N complementary negative resistance differential pair. The series coupling tube and the tail current tube connected to the resistance differential pair tube;

The series coupling tubes in the two VCOs are connected; the diode-connected MOS tube NM4, the low-pass RC filter LPF, and the tail current tubes in the two VCOs are connected in sequence to form a current mirror.

The LC resonant network composed of the inductor and the distributed varactor structure circuit includes:

The distributed varactor structure circuit includes: a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a A varactor Cv1, a second varactor Cv2, a third varactor Cv3 and a fourth varactor Cv4; wherein:

One end of the first capacitor C1 is connected to the first voltage output end, and the other end is connected to the first resistor R1 and the first varactor Cv1; one end of the second capacitor C2 is connected to the second voltage output end, and the other end is connected to the second resistor R2 and the first varactor Cv1. The second varactor Cv2 is connected; one end of the third capacitor C3 is connected to the first voltage output end, and the other end is connected to the third resistor R3 and the third varactor Cv3; one end of the fourth capacitor C4 is connected to the second voltage output end, The other end is connected to the fourth resistor R4 and the fourth varactor Cv4; the other end of the first resistor R1 is connected to the other end of the second resistor R2 and connected to the first bias voltage VB1; the other end of the third resistor R3 is connected to the first bias voltage VB1. The other ends of the four resistors R4 are connected to the second bias voltage VB2; the other ends of the four varactors Cv1-Cv4 are connected together to the control voltage Vcont;

Both ends of the inductance L are respectively connected to the first voltage output end and the second voltage output end of the VCO, thereby forming an LC resonant network with a distributed varactor structure circuit.

The upper P lower N complementary negative resistance differential pair includes: a first switching tube PM1, a second switching tube PM2, a third switching tube NM1 and a fourth switching tube NM2; wherein:

The drain end of the first switching tube PM1 is connected to the drain end of the third switching tube NM1 as the first voltage output end of the VCO; the drain end of the second switching tube PM2 is connected to the drain end of the fourth switching tube NM2 as the output terminal of the VCO a second voltage output terminal;

The gate terminal of the first switch tube PM1 and the gate terminal of the third switch tube NM1 are both connected to the second voltage output terminal, and the gate terminal of the second switch tube PM2 is connected to the first voltage output terminal with the gate terminal of the fourth switch tube NM2;

The upper P and lower N complementary negative resistance differential pair tubes are equivalent to negative resistance, and after being connected to the LC resonant network, energy compensation is performed on the LC resonant network.

The series coupling tubes include: a first coupling tube PMc1 and a second coupling tube PMc2; wherein:

The common source terminal of the first coupling tube PMc1 and the second coupling tube PMc2 is connected to the power supply, the drain terminal of the first coupling tube PMc1 is connected to the source terminal of the first switching tube PM1, and the drain terminal of the second coupling tube PMc2 is connected to the second switching tube PM2 source.

The tail current tube is NM3, the drain of which is connected to the common source of the third switching tube NM1 and the fourth switching tube NM2, and the source is grounded to provide a DC bias for the VCO.

The connection of the series coupling tubes in the two VCOs includes:

The two VCOs are respectively marked as VCO_A and VCO_B, and the series coupling tubes are all PMOS tubes;

VCO_A includes a first voltage output node QP and a second voltage output node QN, the series coupling transistors in VCO_A include a first coupling transistor PMc1a and a second coupling transistor PMc2a, and the common source terminals of the first coupling transistor PMc1a and the second coupling transistor PMc2a connected to the power supply; VCO_B includes the first voltage output node IP and the second voltage output node IN, the series coupling transistor of VCO_B includes the first coupling transistor PMc1b and the second coupling transistor PMc2b, and the common coupling transistor PMc1b and the second coupling transistor PMc2b The source terminal is connected to the power supply;

The first voltage output terminal IP of VCO_B is connected to the gate terminal of the first coupling transistor PMc1a of VCO_A, the second voltage output terminal IN of VCO_B is connected to the gate terminal of the second coupling transistor PMc2a of VCO_A, and the first voltage output terminal QP of VCO_A is connected to VCO_B The gate terminal of the second coupling transistor PMc2b of VCO_A, the second voltage output terminal QN of VCO_A is connected to the gate terminal of the first coupling transistor PMc1b of VCO_B.

The diode-connected MOS transistor NM4, the low-pass RC filter LPF and the tail current transistors in the two VCOs are sequentially connected to form a current mirror including:

The drain terminal of the diode-connected NM4 is connected to the gate terminal, connected to the current source, and the source terminal is grounded. The gate terminal passes through the low-pass RC filter LPF and is connected to the gate terminal of the tail current transistor NM3a in VCO_A and the tail current transistor NM3b in VCO_B. .

It can be seen from the above-mentioned technical solution provided by the present invention that 1) the oscillation unit of the quadrature voltage-controlled oscillator adopts an upper P lower N cross-coupled complementary structure, and such a complementary structure realizes current multiplexing. Only a smaller current is required, which can effectively reduce the power consumption of the circuit. 2) Low phase noise is achieved by the following three points: QVCO adopts the PMOS series coupling method, and the coupling tube and the switching tube are connected into a Cascode structure, which effectively reduces the noise contribution of the coupling tube; in order to obtain the same transconductance, the size of the PMOS should be larger than NMOS, PMOS is used as the coupling tube instead of NMOS, which effectively reduces the 1/f noise of the coupling tube; in the current mirror, NM4 is smaller in size than the tail current tube, adding an RC low-pass filter can filter out part of NM4 and Noise from the external power supply. At the same time, the phase error is only a weak function of the coupling strength, and the phase error and phase noise performance can be optimized simultaneously. 3) A distributed varactor structure is adopted, and two sets of varactor pairs are used, and their linear ranges are respectively controlled by bias voltages VB1 and VB2, which can expand the linear range of the control voltage and improve the linearity of the QVCO gain.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings on the premise of not paying creative work.

Fig. 1 is the circuit diagram of parallel coupling type QVCO in the prior art that the background technology of the present invention provides;

Fig. 2 is the circuit diagram of series coupling type QVCO in the prior art that background technology of the present invention provides;

FIG. 3 is a schematic diagram of a low-power-consumption and low-phase-noise quadrature inductor-capacitor voltage-controlled oscillator circuit provided by an embodiment of the present invention;

4 is a schematic circuit diagram of a distributed varactor structure provided by an embodiment of the present invention;

Fig. 5 is the simulation result schematic diagram of the transient waveform of QVCO that the embodiment of the present invention provides;

6 is a schematic diagram of the simulation results of the phase noise of the QVCO provided by the embodiment of the present invention;

FIG. 7 is a schematic diagram of a simulation result of a phase error of a QVCO provided by an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

An embodiment of the present invention provides a low power consumption and low phase noise quadrature inductor-capacitor voltage-controlled oscillator, as shown in FIG. 3 , which mainly includes: two voltage-controlled oscillators VCO (denoted as VCO_A and VCO_B), diode-connected MOS transistor NM4 and low-pass RC filter LPF;

Among them, each VCO includes: an LC resonant network composed of an inductor and a distributed varactor structure circuit, an upper P lower N complementary negative resistance differential pair connected to the LC resonant network, and an upper P lower N complementary negative resistance differential pair. The series coupling tube and the tail current tube connected to the resistance differential pair tube;

The series coupling tubes in the two VCOs are connected; the diode-connected MOS tube NM4, the low-pass RC filter LPF, and the tail current tubes in the two VCOs are connected in sequence to form a current mirror.

The specific structures of the LC resonant network, the upper P and the lower N complementary negative resistance differential pair tubes, series coupling tubes and tail current tubes will be described in detail below.

1. LC resonant network.

It includes: distributed varactor structure circuit and inductance.

1) As shown in Figure 4, the distributed varactor structure circuit includes: first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C4, first resistor R1, second resistor R2, third resistor R3, the fourth resistor R4, the first varactor Cv1, the second varactor Cv2, the third varactor Cv3 and the fourth varactor Cv4; wherein:

One end of the first capacitor C1 is connected to the first voltage output end, and the other end is connected to the first resistor R1 and the first varactor Cv1; one end of the second capacitor C2 is connected to the second voltage output end, and the other end is connected to the second resistor R2 and the first varactor Cv1. The second varactor Cv2 is connected; one end of the third capacitor C3 is connected to the first voltage output end, and the other end is connected to the third resistor R3 and the third varactor Cv3; one end of the fourth capacitor C4 is connected to the second voltage output end, The other end is connected to the fourth resistor R4 and the fourth varactor Cv4; the other end of the first resistor R1 is connected to the other end of the second resistor R2 and connected to the first bias voltage VB1; the other end of the third resistor R3 is connected to the first bias voltage VB1. The other ends of the four resistors R4 are connected to the second bias voltage VB2; the other ends of the four varactors Cv1-Cv4 are connected together to the control voltage Vcont.

2) Both ends of the inductance L are respectively connected to the first voltage output terminal and the second voltage output terminal of the VCO, thereby forming an LC resonant network with a distributed varactor structure circuit.

Those skilled in the art can understand that adding a or b to the end of each of the above components means the components in VCO_A or VCO_B; for example, adding a to the end of the first capacitor C1 above means that the first A capacitor C1a is represented as a component in VCO_A; b is added to the end of the first capacitor C1 above, that is, the first capacitor C1b is represented as a component in VCO_B. Of course, the various components that appear later are also similar, so they will not be described in detail, but the representation of the above marks is only for distinguishing, not to limit the solution itself.

2. Upper P and lower N complementary negative resistance differential pair tubes.

It mainly includes: a first switching tube PM1, a second switching tube PM2, a third switching tube NM1 and a fourth switching tube NM2; wherein:

The drain terminal of the first switching tube PM1 is connected to the drain terminal of the third switching tube NM1 as the first voltage output terminal of the VCO; the second switching tube PM2 is connected to the drain terminal of the fourth switching tube NM2 as the second voltage of the VCO output terminal;

The gate terminal of the first switch tube PM1 and the gate terminal of the third switch tube NM1 are both connected to the second voltage output terminal, and the gate terminal of the second switch tube PM2 is connected to the first voltage output terminal with the gate terminal of the fourth switch tube NM2;

The upper P and lower N complementary negative resistance differential pair tubes are equivalent to negative resistance, and after being connected to the LC resonant network, energy compensation is performed on the LC resonant network.

3. Series coupling tube.

It mainly includes: the first coupling tube PMc1 and the second coupling tube PMc2; where:

The common source terminal of the first coupling tube PMc1 and the second coupling tube PMc2 is connected to the power supply, the drain terminal of the first coupling tube PMc1 is connected to the source terminal of the first switching tube PM1, and the drain terminal of the second coupling tube PMc2 is connected to the second switching tube PM2 source.

4. Tail current tube.

The tail current tube is NM3, the drain of which is connected to the common source of the third switching tube NM1 and the fourth switching tube NM2, and the source is grounded to provide a DC bias for the VCO.

In the embodiment of the present invention, VCO_A and VCO_B are connected through series coupling transistors; the series coupling transistors are all PMOS transistors. 3, VCO_A includes a first voltage output node QP and a second voltage output node QN, the series coupling transistors in VCO_A include a first coupling transistor PMc1a and a second coupling transistor PMc2a, the first coupling transistor PMc1a and a second coupling transistor PMc2a The common source of the coupling tube PMc2a is connected to the power supply; VCO_B includes the first voltage output node IP and the second voltage output node IN, the series coupling tube of VCO_B includes the first coupling tube PMc1b and the second coupling tube PMc2b, the first coupling tube PMc1b and the The common source terminal of the second coupling tube PMc2b is connected to the power supply;

The first voltage output terminal IP of VCO_B is connected to the gate terminal of the first coupling transistor PMc1a of VCO_A, the second voltage output terminal IN of VCO_B is connected to the gate terminal of the second coupling transistor PMc2a of VCO_A, and the first voltage output terminal QP of VCO_A is connected to VCO_B The gate terminal of the second coupling transistor PMc2b of VCO_A, the second voltage output terminal QN of VCO_A is connected to the gate terminal of the first coupling transistor PMc1b of VCO_B.

In addition, the drain terminal of the diode-connected NM4 is connected to the gate terminal, connected to the current source, and the source terminal is grounded. The gate terminal passes through the low-pass RC filter LPF, and is connected to the gate of the tail current transistor NM3a in VCO_A and the tail current transistor NM3b in VCO_B. end connected.

Those skilled in the art can understand that the polarity of the MOS transistors can be determined according to the structures shown in Figures 3 to 4; at the same time, it can also be determined according to the marks of the corresponding MOS transistors, that is, those starting with N are NMOS transistors, for example , the third switching tube NM1 and the fourth switching tube NM2 are both NMOS tubes; those starting with P are PMOS tubes, for example, the first switching tube PM1 and the second switching tube PM2 are both PMOS tubes.

The above solution of the embodiment of the present invention mainly has the following advantages compared with the prior art:

1) The oscillation unit of the quadrature voltage-controlled oscillator adopts an upper P lower N cross-coupled complementary structure. Such a complementary structure realizes current multiplexing, and only needs a smaller current under the condition of a certain transconductance, which can effectively reduce the circuit power consumption.

2) Low phase noise is achieved by the following three points: QVCO adopts the PMOS series coupling method, and the coupling tube and the switching tube are connected into a Cascode structure, which effectively reduces the noise contribution of the coupling tube; in order to obtain the same transconductance, the size of the PMOS should be larger than NMOS, PMOS is used as the coupling tube instead of NMOS, which effectively reduces the 1/f noise of the coupling tube; in the current mirror, NM4 is smaller in size than the tail current tube, adding an RC low-pass filter can filter out part of NM4 and Noise from the external power supply. At the same time, the phase error is only a weak function of the coupling strength, and the phase error and phase noise performance can be optimized simultaneously.

3) A distributed varactor structure is adopted, and two sets of varactor pairs are used, and their linear ranges are respectively controlled by bias voltages VB1 and VB2, which can expand the linear range of the control voltage and improve the linearity of the QVCO gain.

On the other hand, in order to verify the present invention, the QVCO proposed in this embodiment is simulated under the 130nm CMOS process. Under the power supply voltage of 1.5V, the QVCO consumes 950uA current, the center frequency is 2.4GHz, and at 1MHz frequency offset The phase noise is -123.9dBc/Hz, and the maximum phase error is 0.7 degrees. We often use the quality factor FOM to characterize the performance of the oscillator, according to the formula of FOM as follows:

Among them, f ₀ represents the center frequency, Δf represents the frequency deviation, P represents the power consumption, and PN(Δf) represents the phase noise at the frequency deviation;

The FOM of the QVCO is obtained as high as 191.4, which shows that the invention has outstanding advantages in low power consumption and low phase noise. Accompanying drawing 5 is the simulation result of the transient waveform of QVCO, accompanying drawing 6 is the simulation result of QVCO phase noise, and accompanying drawing 7 is the simulation result of QVCO phase error.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field can easily conceive of changes or changes within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (7)

1. a kind of orthogonal LC voltage controlled oscillator of low-power consumption low phase noise, it is characterised in that including：Two have phase Isostructural voltage controlled oscillator VCO, the metal-oxide-semiconductor NM4 and low pass R/C filters LPF of diode connection；

Wherein, every VCO includes：LC resonant networks and LC Resonance Neural Networks that inductance is constituted with distributed varactor structure circuit The series coupled that N complementary negative resistance differential pair tube and the negative resistance differential pair tube complementary with N under upper P are connected under the connected upper P of network Pipe and tail current pipe；

Series coupled pipe in two VCO is connected；Metal-oxide-semiconductor NM4, the low pass R/C filters LPF and two VCO of diode connection In tail current pipe be sequentially connected composition current mirror.

2. a kind of orthogonal LC voltage controlled oscillator of low-power consumption low phase noise according to claim 1, its feature It is that the LC resonant networks that the inductance is constituted with distributed varactor structure circuit include：

Distributed varactor structure circuit includes：First electric capacity C1, the second electric capacity C2, the 3rd electric capacity C3, the 4th electric capacity C4, first Resistance R1, second resistance R2,3rd resistor R3, the 4th resistance R4, the first varactor Cv1, the second varactor Cv2, the 3rd transfiguration Pipe Cv3 and the 4th varactor Cv4；Wherein：

The one termination first voltage output end of the first electric capacity C1, the other end is connected with first resistor R1 and the first varactor Cv1；The The one termination second voltage output end of two electric capacity C2, the other end is connected with second resistance R2 and the second varactor Cv2；3rd electric capacity The one termination first voltage output end of C3, the other end is connected with 3rd resistor R3 and the 3rd varactor Cv3；The one of 4th electric capacity C4 Termination second voltage output end, the other end is connected with the 4th resistance R4 and the 4th varactor Cv4；The other end of first resistor R1 with The other end of second resistance R2 is connected, and meets the first bias voltage VB1；The other end of 3rd resistor R3 is another with the 4th resistance R4's End is connected, and meets the second bias voltage VB2；The other end of four varactor Cv1~Cv4 is connected together, and connects control voltage Vcont；

The two ends of inductance L connect the first voltage output end of VCO and second voltage output end respectively, so as to distributed varactor knot The LC resonant networks of structure circuit composition.

3. a kind of orthogonal LC voltage controlled oscillator of low-power consumption low phase noise according to claim 1, its feature It is that N complementary negative resistance differential pair tube includes under the upper P：First switch pipe PM1, second switch pipe PM2, the 3rd switching tube NM1 and the 4th switching tube NM2；Wherein：

The drain terminal of first switch pipe PM1 is connected with the drain terminal of the 3rd switching tube NM1, used as the first voltage output end of VCO；Second The drain terminal of switching tube PM2 is connected with the drain terminal of the 4th switching tube NM2, used as the second voltage output end of VCO；

The grid end of first switch pipe PM1 is all connected with second voltage output end, second switch pipe with the grid end of the 3rd switching tube NM1 The grid end of PM2 is connected first voltage output end with the grid end of the 4th switching tube NM2；

N complementary negative resistance differential pair tube is equivalent to negative resistance under upper P, after being connected with LC resonant networks, energy is carried out to LC resonant networks Amount compensation.

4. a kind of orthogonal LC voltage controlled oscillator of low-power consumption low phase noise according to claim 3, its feature It is that series coupled pipe includes：First coupling pipe PMc1 couples pipe PMc2 with second；Wherein：

First coupling pipe PMc1 couples the common source termination power of pipe PMc2 with second, and the drain terminal of the first coupling pipe PMc1 connects first and opens The source of pipe PM1 is closed, the drain terminal of the second coupling pipe PMc2 connects the source of second switch pipe PM2.

5. a kind of orthogonal LC voltage controlled oscillator of low-power consumption low phase noise according to claim 3, its feature It is that the tail current pipe is NM3, its drain terminal is connected with the 3rd switching tube NM1 with the common source end of the 4th switching tube NM2, source Ground connection, for VCO provides direct current biasing.

6. a kind of orthogonal LC voltage controlled oscillator of low-power consumption low phase noise according to claim 1, its feature It is that the series coupled pipe in described two VCO is connected and includes：

Two VCO are designated as VCO_A and VCO_B respectively, and series coupled pipe therein is PMOS；

VCO_A includes first voltage output node QP and second voltage output node QN, and the series coupled pipe in VCO_A includes the One coupling pipe PMc1a couples pipe PMc2a, the first coupling pipe PMc1a with second and the common source termination electricity of pipe PMc2a is coupled with second Source；VCO_B includes that first voltage output node IP includes first with the series coupled pipe of second voltage output node IN, VCO_B Coupling pipe PMc1b couples pipe PMc2b, the first coupling pipe PMc1b with second and the common source termination power of pipe PMc2b is coupled with second；

The first voltage output end IP of VCO_B connects the grid end of the first coupling pipe PMc1a of VCO_A, the second voltage output of VCO_B End IN connects the grid end of the second coupling pipe PMc2a of VCO_A, and the first voltage output end QP of VCO_A connects the second coupling pipe of VCO_B The grid end of PMc2b, the second voltage output end QN of VCO_A connects the grid end of the first coupling pipe PMc1b of VCO_B.

7. a kind of orthogonal LC voltage controlled oscillator of low-power consumption low phase noise according to claim 6, its feature It is that the tail current pipe in metal-oxide-semiconductor NM4, the low pass R/C filters LPF and two VCO of diode connection is sequentially connected composition Current mirror includes：

The drain terminal of the NM4 of diode connection is connected with grid end, connects current source, and source is grounded, and grid end is by low pass R/C filters LPF, the grid end with the tail current pipe NM3b in tail current pipe NM3a and VCO_B in VCO_A is connected.