An ultra-wideband voltage-controlled oscillator circuit

Abstract

The present invention discloses an ultra-wideband voltage-controlled oscillator circuit, which relates to the technical field of semiconductor integrated circuits and is used to solve the problems of electromagnetic interference risk, narrow frequency adjustment range and high power consumption in the existing voltage-controlled oscillator. It includes a switched capacitor array, a transformer-loaded switched inductor, a variable capacitor and cross-coupled transistors; both ends of the transformer-loaded switched inductor are respectively connected to both ends of the switched capacitor array, and the transformer-loaded switched inductor is connected in parallel with the switched capacitor array; both ends of the switched capacitor array are respectively connected to a variable capacitor, and the variable capacitor is connected to the cross-coupled transistors. By adopting an 8-shaped transformer-loaded switched inductor, the output frequency adjustment range of the single-core voltage-controlled oscillator is expanded, and the problem of serious frequency perturbation caused by electromagnetic interference to external circuit modules is solved. It has a wider frequency adjustment range compared with other single-core LC_VCOs, and has a smaller area and lower power consumption performance compared with other multi-core multi-mode LC_VCOs.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor integrated circuits, and particularly to an ultra-wideband voltage-controlled oscillator circuit. Background Art

[0002] With the rapid development of wireless communication technology and high-speed wired communication technology, communication protocols in different frequency ranges emerge in an endless stream. At the same time, the demand for clock generators that can meet multiple frequency ranges is increasing day by day. The voltage-controlled oscillator with a wide output frequency range, as a key component of the clock generator (phase-locked loop), has become a research hotspot in the academic and industrial circles today.

[0003] Voltage-controlled oscillators can be divided into two categories according to whether an inductance structure is adopted in the circuit. The voltage-controlled oscillator without an inductance is a ring oscillator. The ring oscillator consists of multiple delay units forming a loop, and the phase of the loop open-loop transfer function is ∠H(jw) = -180°, |H(jw)| = 1. There is no inductance in the ring oscillator circuit, which has the advantages of not generating serious electromagnetic interference to the outside world, high design flexibility, wide frequency adjustment range, and small layout area. It is widely used in today's frequency synthesizers with a wide output frequency range. The voltage-controlled oscillator with an inductance is called an inductance-capacitance voltage-controlled oscillator (LC_VCO). The LC_VCO uses an inductance and a capacitance to form a resonator and adds a negative resistance formed by a cross-coupled pair of transistors. When g m R p ≥1, the oscillation starting condition of the oscillator is satisfied. Where g m is the gain coefficient of the cross-coupled pair of transistors, and R p is the parallel parasitic resistance of the resonator. Due to the high Q value of the resonator, the LC_VCO has good phase noise performance and a high figure of merit FOM. However, compared with the ring oscillator, the disadvantage of the LC_VCO is that since the output frequency can only be adjusted by the varactor and the capacitance connected to the resonator, it is difficult to greatly increase the output frequency range of the LC_VCO.

[0004] In the voltage-controlled oscillator architecture in the prior art, the inductance has a large electromagnetic interference to the external system, and there is a risk of electromagnetic interference to other modules on a multi-module chip, narrow frequency adjustment range, and high power consumption.

[0005] Therefore, there is an urgent need to provide a more reliable ultra-wideband voltage-controlled oscillator circuit. Summary of the Invention

[0006] The purpose of the present invention is to provide an ultra-wideband voltage-controlled oscillator circuit to solve the problems of electromagnetic interference risk, narrow frequency adjustment range, and high power consumption of the voltage-controlled oscillator in the prior art.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides an ultra-wideband voltage-controlled oscillator circuit, the circuit comprising:

[0009] A switched capacitor array, a transformer-loaded switched inductor, a variable capacitor, and cross-coupled transistors;

[0010] Both ends of the transformer-loaded switched inductor are respectively connected to both ends of the switched capacitor array, and the transformer-loaded switched inductor is connected in parallel with the switched capacitor array;

[0011] Both ends of the switched capacitor array are respectively connected to a variable capacitor, and the variable capacitor is connected to the cross-coupled transistors.

[0012] Optionally, the cross-coupled transistors include a first MOS transistor and a second MOS transistor;

[0013] The gate of the first MOS transistor and the drain of the second MOS transistor are commonly connected to one end of the transformer-loaded switched inductor, the drain of the first MOS transistor and the gate of the second MOS transistor are commonly connected to the other end of the transformer-loaded switched inductor, and the source of the first MOS transistor and the source of the second MOS transistor are both connected to ground.

[0014] Optionally, the transformer-loaded switched inductor is a figure-eight transformer-loaded switched inductor.

[0015] Optionally, the variable capacitor includes a first capacitor and a second capacitor; a first port of the first capacitor is connected to one end of the switched capacitor array, and a first port of the second capacitor is connected to the other end of the switched capacitor array; a second port of the first capacitor and a second port of the second capacitor are connected to each other.

[0016] Optionally, the transformer-loaded switched inductor includes a primary coil and a secondary coil, and the secondary coil surrounds the primary coil in a figure-eight shape.

[0017] Optionally, the primary coil is the thickest metal layer in the voltage-controlled oscillator circuit; the secondary coil is other metal layers except the primary coil.

[0018] Optionally, based on the simplified model of the transformer-loaded switched inductor, the formula:

[0019] L eff ≈(1-k 2 )L1

[0020]

[0021]

[0022] Calculate the relevant parameter values of the transformer load switch inductor;

[0023] Among them, L eff is the total inductance value of the transformer load switch inductor, R eff is the parasitic resistance of the transformer load switch inductor, Q eff is the main inductor quality factor Q value of the transformer load switch inductor, L1 is the inductance value of the primary coil, L2 is the inductance value of the secondary coil, k is the coupling coefficient between the primary coil and the secondary coil, and R2 is the parasitic resistance of the secondary coil.

[0024] Optionally, the transformer load switch inductor increases the output frequency adjustment range of a single-core voltage-controlled oscillator through transformer load switch technology.

[0025] Optionally, the cross-coupled transistors are used to provide negative resistance for the ultra-wideband voltage-controlled oscillator circuit. When g m R p ≥1, the oscillation starting condition of the oscillator is satisfied; among them, g m is the gain coefficient of the pair of cross-coupled transistors, and R p is the parallel parasitic resistance of the resonator.

[0026] Compared with the prior art, an ultra-wideband voltage-controlled oscillator circuit provided by the present invention includes: a switched capacitor array, a transformer load switch inductor, a variable capacitor, and cross-coupled transistors; both ends of the transformer load switch inductor are respectively connected to both ends of the switched capacitor array, and the transformer load switch inductor is connected in parallel with the switched capacitor array; both ends of the switched capacitor array are respectively connected to a variable capacitor, and the variable capacitor is connected to the cross-coupled transistors. The solution in the present invention first adopts an 8-shaped transformer load switch inductor, expands the output frequency adjustment range of a single-core voltage-controlled oscillator through transformer load switch technology, and uses the 8-shaped inductor to solve the problem of serious frequency disturbance caused by electromagnetic interference to external circuit modules. It has a wider frequency adjustment range compared with other single-core LC_VCOs, and has a smaller area and lower power consumption performance compared with other multi-core multi-mode LC_VCOs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0028] Figure 1 is a schematic diagram of the inductor switch technology;

[0029] Figure 2 is a schematic diagram of the transformer load switch inductor in the first prior art;

[0030] Figure 3 Schematic diagram of an LC_VCO using an existing transformer load switching inductor in the prior art one;

[0031] Figure 4 Output spectrum diagram of an LC_VCO using an existing transformer load switching inductor in the prior art one;

[0032] Figure 5 Schematic diagram of a high tuning range dual-core figure-eight VCO in the prior art two;

[0033] Figure 6 Schematic diagram of a circuit structure of an ultra-wideband voltage-controlled oscillator provided by the present invention;

[0034] Figure 7 Schematic diagram of a switched capacitor array in a circuit of an ultra-wideband voltage-controlled oscillator provided by the present invention;

[0035] Figure 8 Schematic diagram of a figure-eight transformer load switching inductor provided by the present invention;

[0036] Figure 9 Schematic diagram of a simplified model of a transformer load switching inductor provided by the present invention.

[0037] Reference numerals:

[0038] 1 - Transformer load switching inductor, 2 - Switched capacitor array, 3 - Variable capacitor, 4 - Cross-coupled transistor. Detailed implementation manners

[0039] For the convenience of clearly describing the technical solutions of the embodiments of the present invention, in the embodiments of the present invention, terms such as "first" and "second" are used to distinguish identical or similar items with basically the same functions and effects. For example, the first threshold and the second threshold are only used to distinguish different thresholds, and do not limit their sequence. Those skilled in the art can understand that the terms "first" and "second" do not limit the quantity and execution order, and the terms "first" and "second" do not necessarily limit to be different.

[0040] It should be noted that in the present invention, words such as "exemplary" or "for example" are used to represent examples, illustrations or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the present invention should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Exactly, using words such as "exemplary" or "for example" aims to present relevant concepts in a specific manner.

[0041] In the present invention, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the relationship between associated objects and indicates that there can be three relationships. For example, A and / or B can represent the cases of A existing alone, A and B existing simultaneously, and B existing alone, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. "At least one (item)" or similar expressions refer to any combination of these items, including any combination of single item(s) or plural item(s). For example, at least one (item) of a, b, or c can represent: a, b, c, the combination of a and b, the combination of a and c, the combination of b and c, or the combination of a, b, and c, where a, b, and c can be single or multiple.

[0042] The phase noise performance of the LC_VCO is better than that of ring oscillators and other similar oscillators. Therefore, the LC_VCO is often used in base stations and cellular phone applications with high requirements for phase noise. Thus, the LC_VCO with low external electromagnetic interference and a large output frequency range has become a hot research topic in the academic community today. For a wideband output LC_VCO, under the current advanced CMOS process conditions, the single-mode LC_VCO can only achieve a 40% frequency tuning range. Considering the fluctuations in the circuit output frequency caused by factors such as process, temperature, and voltage, as well as the overlap margin problem during different capacitor switching, the actual frequency tuning range of the single-mode LC_VCO is only about 20%. Therefore, only by adopting the multi-mode switching method can a wide output frequency range of the LC_VCO be achieved. Currently, multi-mode switching technologies are mainly divided into: inductor switching technology (Iductor Sitching), transformer-loaded switching technology (Transformer-Loaded Switching), multi-core switching technology (Multicore Switching), and multi-mode resonance switching technology (Multimode Resonance Switching).

[0043] Among them, the inductor switching technology realizes the variable inductor in the resonator by switching the inductor. Usually, the inductor in the resonator is switched off into several segments through the inductor switch in the resonator, and different inductance values in different resonators are achieved through the on / off of the switch, so as to achieve the purpose of expanding the output frequency range of the LC_VCO. Its simple schematic diagram is as Figure 1As shown, when the switch SW in the circuit is turned on, the inductor connected between the resonant cavities A and B is 2L1. When the switch is turned off, the inductor connected between the resonant cavities A and B is 2(L1 + L2). The transformer load switch technology also expands the output frequency range of the LC_VCO by changing the inductor value in the resonant cavity. It mainly realizes different transformer load conditions by controlling the switch to achieve different total inductor values of the transformer. It can be divided into two categories: parallel load switch and series load switch. For the series transformer load switch, different transformer load conditions are realized through the switch. When the switch closing conditions are different, the inductor values of the transformer are also different. Therefore, the inductor value between the resonant cavities A and B will also change accordingly. For the parallel load switch, the number of secondary coils in the transformer is realized through the switch to control the inductor value between the resonant cavities A and B;

[0044] The simplest way to implement an LC_VCO with a wide adjustment range using the multi-core switch technology is to directly parallel-oscillate multiple VCO cores and alternately use the outputs of these cores as the output of the final LC_VCO. The multi-mode resonant switch technology changes the inductor or capacitor in the resonator by using the even or odd coupling modes of the inductor or capacitor, thereby expanding the output frequency range of the entire LC_VCO.

[0045] The above four technologies for expanding the output frequency adjustment range of the LC_VCO mainly adjust the inductor value in the resonant cavity through different modes, and finally achieve a wide output frequency adjustment range of the LC_VCO under multiple modes.

[0046] Among the various existing technologies for expanding the output frequency adjustment range, regarding the transformer load switch technology, it can be illustrated by the following two existing technologies:

[0047] Existing Technology 1

[0048] This design uses a transformer load switch voltage-controlled oscillator composed of a primary inductor and two switched secondary coils. The layout of this inductor is as Figure 2 shown. The light gray part is the ninth-layer metal as the primary coil L1, and the secondary coil is made of the eighth-layer metal and can be controlled to close and open by the switches SW1 and SW2. The specific circuit of the VCO using this inductor is as Figure 3 shown. In this circuit, a CMOS VCO structure is used. M1 and M2 are PMOS cross-coupled pairs, and M3 and M4 form NMOS cross-coupled pairs. The inductor and capacitor form a resonant cavity. Its output frequency coverage range is as Figure 4 shown, from Figure 4It can be seen that by using a transformer-loaded switched inductor, this VCO based on a 65-nm CMOS process achieves a 14% output frequency tuning range, with the output frequency ranging from 49.2 GHz to 56.6 GHz, and the phase noise at a 1-MHz frequency offset being -87 dBc / Hz to -93 dBc / Hz. The optimal figure of merit FOM A is -196.3 dBc / Hz, the DC power consumption is 7.2 mW, and the chip area is 0.5 mm 2 .

[0049] Under the condition of only using one core, this circuit realizes three modes through the method of transformer-loaded switching, achieving a relatively wide frequency tuning range. And it achieves a relatively high figure of merit on the premise of a small chip area and low power consumption.

[0050] For the VCO architecture proposed in the above-mentioned prior art 1, although the output frequency coverage range is increased, the frequency tuning range is 14%, which is insufficient for multi-standard communication protocols. And there is a large electromagnetic interference from the inductor to the external system in this architecture, posing a risk of electromagnetic interference to other modules on a multi-module chip.

[0051] Prior art two

[0052] In order to meet the requirements of the entire system on the same chip, there are often multiple circuit modules. For example, in a Serdes communication chip, there are not only frequency synthesizers, but also low-noise amplifiers and power amplifiers and other modules. There are often inductors operating at different frequencies in these modules. Therefore, an LC_VCO that generates less electromagnetic interference to other modules is for a stable and compact system-on-chip.

[0053] A kind of LC_VCO proposed in the prior art that can generate extremely low electromagnetic interference and achieve more than one octave. If the VCO frequency tuning range exceeds one octave, then it is easy to synthesize frequencies below one octave through frequency division by 2. In theory, full-frequency coverage can be achieved through multiple frequency dividers by 2. And in modern communication systems, there are usually multiple frequency synthesizers working simultaneously. When the VCO frequencies in each frequency synthesizer are close to each other, due to electromagnetic interference problems, serious frequency pulling or perturbation phenomena will occur between the VCOs. Even if there is no harmonic relationship between two VCOs, there will still be a problem of magnetic field mutual attraction. This problem will greatly affect the normal operation of the entire system. The 8-shaped inductor effectively suppresses the electromagnetic interference to the outside world and adopts such as Figure 5The structure shown adopts a multi-core switching technology and uses two parallel VCOs with figure-eight inductors. The output frequency is selected through a switch to expand the output frequency range. Among them, the LowBandVCO can achieve an output frequency of 2.4 GHz to 3.6 GHz, and the frequency adjustment range is 40%. The HighBandVCO can achieve an output frequency of 3.4 GHz to 5.3 GHz, and the frequency adjustment range is 43%. After synthesis through the switch, the total output frequency adjustment range is 75%. This dual-core VCO is implemented in a 65nm CMOS process, with a phase noise of -139 dBc / Hz to -149 dBc / Hz at a 10 MHz frequency offset, a power consumption of 4.4 to 6 mW, and a figure of merit FOM of 187 dBc to 189 dBc. This design uses a figure-eight inductor to suppress electromagnetic interference to the outside world. And a dual-core structure is adopted to achieve an ultra-wide frequency tuning range. And a relatively high phase noise performance is achieved. However, the solution in the prior art II adopts a dual-core structure. Compared with the single-core structure, the dual-core structure VCO has higher power consumption and larger area. And this structure has higher design requirements for the output frequency selector, with a certain design difficulty and higher power consumption.

[0054] To solve the problems in the prior art, the present invention proposes a single-core low-phase-noise LC_VCO with an ultra-wide frequency adjustment range. This voltage-controlled oscillator first uses a figure-eight transformer-loaded switched inductor to expand the output frequency adjustment range of the single-core LC_VCO through the transformer-loaded switching technology. The figure-eight inductor effectively solves the problem of serious frequency perturbation caused by electromagnetic interference to external circuit modules. And the present invention can achieve a frequency adjustment range of more than 50% in the single-core dual-mode case, has a wider frequency adjustment range compared with other single-core LC_VCOs, and has a smaller area and lower power consumption performance compared with other multi-core multi-mode LC_VCOs.

[0055] Next, the solution provided in the embodiments of this specification will be described in conjunction with the accompanying drawings:

[0056] As Figure 6 shown, an ultra-wideband voltage-controlled oscillator circuit provided by the present invention is characterized in that the circuit includes:

[0057] A switched capacitor array 2, a transformer-loaded switched inductor 1, a variable capacitor 3, and a cross-coupled transistor 4;

[0058] Both ends of the transformer-loaded switched inductor 1 are respectively connected to both ends of the switched capacitor array 2, and the transformer-loaded switched inductor 1 is connected in parallel with the switched capacitor array 2;

[0059] Both ends of the switched capacitor array 2 are respectively connected to a variable capacitor 3, and the variable capacitor 3 is connected to the cross-coupled transistor 4.

[0060] As Figure 6 shown, the voltage-controlled oscillator mainly consists of four parts: an 8-shaped transformer-loaded switching inductor 1, a switched capacitor array 2 (Capbank), a variable capacitor 3, and cross-coupled transistors 4.

[0061] Among them, the cross-coupled transistors 4 are mainly composed of two MOS transistors M1 and M2, providing negative resistance for the circuit. When g m R p ≥ 1, the oscillation starting condition of the oscillator is satisfied. Where g m is the gain coefficient of the cross-coupled pair transistors, and R p is the parallel parasitic resistance of the resonator.

[0062] The variable capacitor 3 consists of Figure 6 two C V in. When the control voltage V CTRL increases, the capacitance value of the capacitor C V decreases. Thus, the output frequency of the LC_VCO will increase.

[0063] In the transformer-loaded switched voltage-controlled oscillator, the first end of the transformer-loaded switching inductor 1 is connected to the first end of the switched capacitor array 2, and the second end of the transformer-loaded switching inductor 1 is connected to the second end of the switched capacitor array 2. The second ports of the two varactor diodes C V are connected to each other, and the first ports of the two varactor diodes C V are respectively connected to the first port and the second port of the switched capacitor array 2. The gates of the NMOS transistors M1 and the drains of the NMOS transistors M2 are commonly connected to the first port of the transformer load switch, and the drains of the NMOS transistors M1 and the gates of the NMOS transistors M2 are commonly connected to the second port of the transformer load switch. The sources of the two NMOS transistors are connected to the ground.

[0064] Figure 6 The ultra-wideband voltage-controlled oscillator circuit in

[0065] Based onFigure 6 Regarding the structure, the embodiments of this specification also provide some specific implementation solutions for this structure, which will be described below.

[0066] An example of the basic unit of the switched capacitor array 2 (Capbank) is as Figure 7 shown. When controlling the switches SW[N:0], the number of capacitors incorporated into the LC_VCO resonator is controlled by an (N + 1)-bit digital signal. In a single basic capacitor unit, when SW is low, the capacitor incorporated into the resonator is C DM . When the SW signal is high, the capacitor incorporated into the resonator is C DM ||C gs , and C gs is the parasitic capacitance of the switching MOS transistor in the basic unit.

[0067] The transformer-loaded switched inductor 1 provided in the present invention is an 8-shaped transformer-loaded switched inductor. The specific structural diagram is as Figure 8 shown. The thickest metal layer M9 is used as the primary inductor, so as to obtain the optimal inductance Q value. Other metal layers Mn are used as the secondary coils, and the number of secondary coils can be 1, 2, 3... When the switch TSW is high, the secondary coil conducts.

[0068] Figure 8 The primary inductor in [reference] contains three ports. The lowest end is the tapped VDDVCO; the top left is VCOP; the right is VCON. The secondary inductor surrounds the primary coil in an 8-shaped manner and also has three ports. The top is the center tap VDD; the bottom left is S2N connected to the drain of the switching MOS transistor, and the bottom right is S2P connected to the source of the switching MOS transistor. The gate of the switching MOS transistor is connected to the control signal TSW N , when the control signal TSW N is high, the switch conducts.

[0069] Figure 8 In the 8-shaped inductor in [reference], when current flows, the magnetic induction lines in the lower cavity are in the opposite direction to those in the upper cavity. Therefore, for an ideal symmetric 8-shaped inductor, the magnetic flux contribution to the outside is zero, and it will not cause electromagnetic interference to other peripheral modules.

[0070] And Figure 8 the simplified model corresponding to the simplified transformer-loaded switched inductor in [reference] is as Figure 9 shown. Based on Figure 9 the simplified model in [reference], the relevant parameter values of the transformer-loaded switched inductor can be calculated as:

[0071] L eff ≈(1 - k 2 )L1 (1)

[0072]

[0073]

[0074] Among them, L eff is the total inductance value of the transformer load switch inductor, R eff is the parasitic resistance of the transformer load switch inductor, Q eff is the main inductance quality factor Q value of the transformer load switch inductor, L1 is the inductance value of the primary coil, L2 is the inductance value of the secondary coil, k is the coupling coefficient between the primary coil and the secondary coil, and R2 is the parasitic resistance of the secondary coil.

[0075] To further illustrate the beneficial effects brought by the technical solution of the present invention, next, it will be described by way of example:

[0076] Taking an 8-shaped transformer load switch inductor LC_VCO designed using the TSMC 28nm CMOS process with an output frequency adjustment range exceeding 50% as an example, the 8-shaped transformer load switch inductor is IND20G_V6, and the M9 thick metal layer is used as the primary coil to obtain a higher total quality factor Q eff . Two turns of switchable secondary coils are made using the M8 and AP layer metals. After simulation, the present invention realizes an output frequency from 12.66 GHz to 25.5 GHz. The LC_VCO adopting the architecture of the present invention has high phase noise performance. At an output frequency of 24 GHz, the power consumption is 5.4 mW. The phase noise at 1 MHz offset frequency is -107.46 dBc / Hz. When simulating using the solution of the present invention, the simulation result data under the three set modes are: Mode 1 can cover a range of 12.64 GHz to 20.19 GHz; Mode 2 frequency coverage range is 13.84 GHz to 23.74 GHz; Mode 3 frequency coverage range is 16.14 GHz to 25.44 GHz. Combining the three modes, it can be seen that the voltage-controlled oscillator can achieve a maximum frequency of 25.44 GHz, a minimum frequency of 12.64 GHz, and a center frequency of 19.04 GHz. The formula for calculating the frequency tuning range is:

[0077] Frequency tuning range = (highest output frequency - lowest output frequency) / center frequency;

[0078] Substituting the highest output frequency, the lowest output frequency, and the center frequency into the frequency tuning range calculation formula, the frequency tuning range of the voltage-controlled oscillator can be obtained as 67%.

[0079] Therefore, the present invention proposes a single-core low-phase-noise LC_VCO with an ultra-wide frequency tuning range. For the first time, the voltage-controlled oscillator uses an 8-shaped transformer-loaded switched inductor, which expands the output frequency tuning range of the single-core LC_VCO through transformer-loaded switching technology. The use of the 8-shaped inductor effectively solves the problem of serious frequency perturbation caused by electromagnetic interference to external circuit modules. It has a wider frequency tuning range compared with other single-core LC_VCOs, and has a smaller area and lower power consumption performance compared with other multi-core multi-mode LC_VCOs. More specifically, the present invention can achieve a frequency tuning range of over 50% in the case of a single-core dual-mode.

[0080] Although the present invention has been described in connection with various embodiments, however, in the process of implementing the claimed invention, those skilled in the art can understand and realize other variations of the disclosed embodiments by viewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions recited in the claims. Certain measures are recited in mutually different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0081] Although the present invention has been described in connection with specific features and their embodiments, it is obvious that various modifications and combinations can be made without departing from the spirit and scope of the present invention. Accordingly, the present specification and the drawings are merely exemplary illustrations of the invention defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the present invention. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A ultra-wideband voltage-controlled oscillator circuit, characterized in that The circuit includes: a switched capacitor array, a transformer-loaded switched inductor, a variable capacitor, and cross-coupled transistors; Both ends of the transformer-loaded switched inductor are respectively connected to both ends of the switched capacitor array, and the transformer-loaded switched inductor is connected in parallel with the switched capacitor array; Both ends of the switched capacitor array are respectively connected to a variable capacitor, and the variable capacitor is connected to the cross-coupled transistors; The transformer-loaded switched inductor is an 8-shaped transformer-loaded switched inductor. The thickest metal layer M9 is used as the primary inductor to obtain the optimal inductance Q value, and other metal layers Mn are used as the secondary coils; The 8-shaped transformer load switch inductor uses the M9 thick metal layer as the primary coil to obtain a higher overall quality factor Q eff , the overall quality factor Q eff Based on the simplified model of the transformer load switch inductor, the formula is used: L eff ≈(1 - k 2 )L1 Calculate the relevant parameter values of the transformer-loaded switched inductor; Among them, L eff is the total inductance value of the inductor of the transformer load switch, R eff is the parasitic resistance of the inductor of the transformer load switch, Q eff is the quality factor Q value of the primary inductor of the inductor of the transformer load switch, L1 is the inductance value of the primary coil, L2 is the inductance value of the secondary coil, k is the coupling coefficient between the primary coil and the secondary coil, R2 is the parasitic resistance of the secondary coil, ω represents the angular frequency; the inductor of the transformer load switch increases the output frequency adjustment range of the single-core voltage-controlled oscillator through the transformer load switch technology.

2. The ultra-wideband voltage-controlled oscillator circuit according to claim 1, characterized in that, The cross-coupled transistors include a first MOS transistor and a second MOS transistor; The gate of the first MOS transistor and the drain of the second MOS transistor are commonly connected to one end of the transformer-loaded switched inductor, the drain of the first MOS transistor and the gate of the second MOS transistor are commonly connected to the other end of the transformer-loaded switched inductor, and the sources of the first MOS transistor and the second MOS transistor are both connected to ground.

3. The ultra-wideband voltage-controlled oscillator circuit according to claim 1, characterized in that The variable capacitor includes a first capacitor and a second capacitor; a first port of the first capacitor is connected to one end of the switched capacitor array, and a first port of the second capacitor is connected to the other end of the switched capacitor array; a second port of the first capacitor and a second port of the second capacitor are connected to each other.

4. The ultra-wideband voltage-controlled oscillator circuit according to claim 1, characterized in that The transformer-loaded switched inductor includes a primary coil and a secondary coil, and the secondary coil surrounds the primary coil in an eight-shaped manner.

5. The ultra-wideband voltage-controlled oscillator circuit according to claim 4, wherein, The primary coil is the thickest metal layer in the voltage-controlled oscillator circuit; the secondary coil is other metal layers except the primary coil.

6. The ultra-wideband voltage-controlled oscillator circuit according to claim 2, wherein The cross-coupled tube is used to provide negative resistance for the ultra-wideband voltage-controlled oscillator circuit. When g m R p ≥ 1, the oscillation startup condition of the oscillator is satisfied. Among them, g m is the gain coefficient of the pair of tubes of the cross-coupled tube, and R p is the parallel parasitic resistance of the resonator.

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