Ultra-wideband voltage-controlled oscillator circuit

Abstract

The invention discloses an ultra-wideband voltage-controlled oscillator circuit, relates to the technical field of semiconductor integrated circuits, and is used for solving the problems of electromagnetic interference risk, narrow frequency regulation range and relatively high power consumption of a voltage-controlled oscillator in the prior art. Comprising a switched capacitor array, a transformer load switch inductor, a variable capacitor and a cross coupling tube, two ends of the transformer load switch inductor are respectively connected with two ends of the switch capacitor array, and the transformer load switch inductor is connected with the switch capacitor array in parallel; the two ends of the switched capacitor array are respectively connected with a variable capacitor, and the variable capacitors are connected with the cross coupling tube. By adopting the 8-shaped transformer load switch inductor, the output frequency regulation range of the single-core voltage-controlled oscillator is expanded, and the problem of serious frequency disturbance caused by electromagnetic interference to an external circuit module is solved. Compared with other single-core LCVCOs, the multi-core multi-mode LCVCOs have a wider frequency regulation range, and compared with other multi-core multi-mode LCVCOs, the multi-core multi-mode LCVCOs have a smaller area and lower power consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor integrated circuits, and in particular 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. As a key component of clock generators (phase-locked loops), voltage-controlled oscillators with a wide output frequency range have become a hot topic in academic and industrial research today.

[0003] Voltage-controlled oscillators can be divided into two categories according to whether an inductor structure is used in the circuit. A voltage-controlled oscillator that does not use an inductor is a ring voltage-controlled oscillator. The ring oscillator is composed of multiple delay units to form a loop, and the phase of the loop open-loop transfer function is ∠H(jw)=-180°, |H(jw)|=1. There is no inductor in the ring oscillator circuit, which has the advantages of not causing 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 wide output frequency range frequency synthesizers. The voltage-controlled oscillator using inductance is called an inductor-capacitor voltage-controlled oscillator (LC_VCO). The LC_VCO uses an inductor and a capacitor to form a resonant cavity, and then forms a negative resistance by a cross-coupling pair of tubes. When g m R p ≥1, the oscillator start-up condition is met. m is the cross-coupled tube gain coefficient, R p Parasitic resistance in parallel with the resonant cavity. Due to the high Q value of the resonant cavity, the LC_VCO has good phase noise performance and a high quality factor FOM. However, compared with the ring oscillator, the disadvantage of the LC_VCO is that since this structure can only adjust the output frequency through the varactor and the capacitor connected to the resonant cavity, it is difficult to significantly improve the output frequency range of the LC_VCO.

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

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

[0006] The object of the present invention is to provide an ultra-wideband voltage-controlled oscillator circuit, which is used 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] In order 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] Switched capacitor arrays, transformer load switch inductors, variable capacitors, and cross-coupled transistors;

[0010] The two ends of the transformer load switch inductor are respectively connected to the two ends of the switch capacitor array, and the transformer load switch inductor is connected in parallel with the switch capacitor array;

[0011] Two ends of the switch capacitor array are respectively connected to a variable capacitor, and the variable capacitor is connected to the cross-coupling tube.

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

[0013] The gate of the first MOS tube and the drain of the second MOS tube are commonly connected to one end of the transformer load switch inductor, the drain of the first MOS tube and the gate of the second MOS tube are commonly connected to the other end of the transformer load switch inductor, and the source of the first MOS tube and the source of the second MOS tube are both connected to the ground.

[0014] Optionally, the transformer load switch inductor is an 8-shaped transformer load switch inductor.

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

[0016] Optionally, the transformer load switch 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; and the secondary coil is other metal layers except the primary coil.

[0018] An alternative, simplified model based on the transformer load switch inductance is used using the equation:

[0019] L eff ≈(1-k 2 )L1

[0020]

[0021]

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

[0023] Among them, L eff is the total inductance of the transformer load switch inductor, R eff is the parasitic resistance of the transformer load switch inductor, Q eff is the primary inductance quality factor Q value of the transformer load switch inductor, L1 is the primary coil inductance, L2 is the secondary coil inductance, 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 the single-core voltage-controlled oscillator through transformer load switch technology.

[0025] Optionally, the cross-coupled transistor is used to provide negative resistance for the ultra-wideband voltage-controlled oscillator circuit. m R p ≥1, the oscillator start-up condition is met; where g m is the pair gain coefficient of the cross-coupled tube, R p Parasitic resistance in parallel with the resonant cavity.

[0026] Compared with the prior art, the present invention provides an ultra-wideband voltage-controlled oscillator circuit, including: a switch capacitor array, a transformer load switch inductor, a variable capacitor and a cross-coupled tube; the two ends of the transformer load switch inductor are respectively connected to the two ends of the switch capacitor array, and the transformer load switch inductor is connected in parallel with the switch capacitor array; the two ends of the switch capacitor array are respectively connected to a variable capacitor, and the variable capacitor is connected to the cross-coupled tube. The solution in the present invention adopts an 8-shaped transformer load switch inductor for the first time, and expands the output frequency adjustment range of the single-core voltage-controlled oscillator through the transformer load switch technology. The use of the 8-shaped inductor solves the problem of serious frequency disturbance caused by electromagnetic interference to the external circuit module. Compared with other single-core LC_VCOs, it has a wider frequency adjustment range, and compared with other multi-core multi-mode LC_VCOs, it has a smaller area and lower power consumption. 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 exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0028] Figure 1 It is a schematic diagram of inductive switching technology;

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

[0030] Figure 3 It is a schematic diagram of LC_VCO using the existing transformer load switch inductor in the prior art 1;

[0031] Figure 4 This is a spectrum diagram of the LC_VCO output using the existing transformer load switch inductance in the prior art 1;

[0032] Figure 5 Schematic diagram of a dual-core figure-8 VCO with a medium to high tuning range in the prior art II;

[0033] Figure 6 The present invention provides a schematic diagram of the circuit structure of an ultra-wideband voltage-controlled oscillator;

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

[0035] Figure 8 A schematic diagram of the 8-shaped transformer load switch inductor provided by the present invention;

[0036] Fig. 9 This is a schematic diagram of a simplified model of the transformer load switch inductance provided by the present invention.

[0037] Reference numerals:

[0038] 1- Transformer load switch inductor, 2- Switch capacitor array, 3- Variable capacitor, 4- Cross-coupled tube. DETAILED DESCRIPTION

[0039] In order to clearly describe the technical solutions of the embodiments of the present invention, in the embodiments of the present invention, words such as "first" and "second" are used to distinguish the same items 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 their order is not limited. Those skilled in the art can understand that words such as "first" and "second" do not limit the quantity and execution order, and words such as "first" and "second" do not necessarily limit them to be different.

[0040] It should be noted that, in the present invention, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0041] In the present invention, "at least one" means one or more, and "plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists 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 of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: 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, c can be single or multiple.

[0042] The phase noise performance of LC_VCO is better than that of ring oscillators and other similar oscillators. Therefore, LC_VCO is often used in base stations and cellular phone applications with high phase noise requirements. Therefore, LC_VCO with low external electromagnetic interference and large output frequency range has become a hot topic in academic research today. As for wide-band output LC_VCO, under today's advanced CMOS process conditions, single-mode LC_VCO can only achieve a 40% frequency adjustment 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 when different capacitors are switched, the actual frequency adjustment range of single-mode LC_VCO is only about 20%. Therefore, only by using multi-mode switching can the wide output frequency range of LC_VCO be achieved. Today, multi-mode switching technology is mainly divided into: inductor switching technology (IductorSitching), transformer-loaded switching technology (Transformer-Loaded Switching), multi-core switching technology (Multicore Switching) and multi-mode resonant switching technology (MultimodeResonance Switching).

[0043] Among them, the inductor switch technology is to achieve variable inductance in the resonant cavity by switching the inductor. Usually, the inductor switch in the resonant cavity is used to cut the switch in the resonant cavity into several sections, and different inductance values ​​in different resonant cavities are achieved by turning the switch on and off, so as to achieve the purpose of expanding the output frequency range of LC_VCO. Its simple schematic diagram is as follows Figure 1As shown, when the switch SW in the circuit is turned on, the inductance connected between the resonant cavity AB is 2L1. When the switch is turned off, the inductance connected between the resonant cavity AB is 2(L1+L2). The transformer load switch technology also expands the output frequency range of LC_VCO by changing the inductance value in the resonant cavity. Different transformer load conditions are mainly achieved by controlling the switch to achieve different total transformer inductance values. It can be divided into two categories: parallel load switch and series load switch. The series transformer load switch achieves different transformer load conditions through the switch. When the switch closure conditions are different, the transformer inductance value is also different. Therefore, the inductance value between the resonant cavity AB will also change accordingly. The parallel load switch controls the inductance value between the resonant cavity AB by switching to realize the number of secondary coils in the transformer;

[0044] The simplest way to achieve a LC_VCO with a wide adjustment range is to directly use multiple VCO cores in parallel and alternate the outputs of these cores as the final LC_VCO output. Multi-mode resonant switching technology uses the even or odd coupling modes of inductance or capacitance to change the inductance or capacitance in the resonator, thereby expanding the output frequency range of the entire LC_VCO.

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

[0046] Among the various technologies for expanding the output frequency adjustment range in the prior art, the transformer load switch technology can be described by the following two prior arts:

[0047] Prior art 1

[0048] The design uses a transformer load switch voltage controlled oscillator consisting of a primary inductor and two switched secondary coils. The inductor layout is shown in Figure 2 As shown in FIG. 1 , the light gray part is the ninth metal layer as the primary coil L1, and the secondary coil is made of the eighth metal layer, and the closing and opening of the secondary coil can be controlled by switches SW1 and SW2. The specific circuit of the VCO using this inductor is as follows Figure 3 As shown in the figure, the CMOS VCO structure is used in this circuit, M1 and M2 are PMOS cross-coupled pairs, while M3 and M4 form NMOS cross-coupled pairs, and the inductor and capacitor form a resonant cavity. Its output frequency coverage range is as follows Figure 4 As shown, from Figure 4It can be seen that: using the transformer load switch inductor, the VCO based on the 65nm CMOS process achieves a 14% output frequency adjustment range, the output frequency is realized from 49.2GHz to 56.6GHz, and the phase noise at 1MHz frequency offset is -87dBc / Hz to -93dBc / Hz. The best quality factor FOM A The chip area is 0.5mm. 2 .

[0049] The circuit realizes three modes by means of transformer load switch under the condition of using only one core, achieving a wide frequency adjustment range and achieving a high quality factor under the premise of small chip area and low power consumption.

[0050] Although the VCO architecture proposed in the above prior art 1 increases the output frequency coverage, the frequency adjustment range is 14%, which is insufficient for multi-standard communication protocols. In addition, the inductor in this architecture 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.

[0051] Prior art 2

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

[0053] A LC_VCO proposed in the prior art can generate extremely low electromagnetic interference and achieve more than one octave. If the VCO frequency adjustment range exceeds one frequency, it is easy to synthesize a frequency lower than one octave by dividing by 2. In theory, full-frequency coverage can be achieved through multiple 2-dividers. Moreover, in modern communication systems, there are usually multiple frequency synthesizers working at the same time. When the VCO frequencies in each frequency synthesizer are close to each other, serious frequency pulling or disturbance will occur between the VCOs due to electromagnetic interference problems. Even if there is no harmonic relationship between the two VCOs, there will be a problem of mutual pulling of the magnetic field. This problem will greatly affect the normal operation of the entire system. The use of an 8-shaped inductor can effectively suppress electromagnetic interference to the outside world, and the use of Figure 5The structure shown in FIG. 1 adopts multi-core switch technology and two VCOs with 8-shaped inductors are connected in parallel. The output frequency is selected by switching to expand the output frequency range. Among them, LowBand VCO can achieve an output frequency of 2.4 GHz to 3.6 GHz, and the frequency adjustment range is 40%. HighBand VCO can achieve an output frequency of 3.4 GHz to 5.3 GHz, and the frequency adjustment range is 43%. After switching synthesis, the total output frequency adjustment range is 75%. The dual-core VCO is implemented on a 65nm CMOS process, and the phase noise at a frequency offset of 10 MHz is -139 dBc / Hz to -149 dBc / Hz, its power consumption is 4.4 to 6 mW, and the quality factor FOM is 187 dBc to 189 dBc. The design uses 8-shaped inductors to suppress electromagnetic interference to the outside world. And the dual-core structure is used to achieve an ultra-wide frequency tuning range. And a higher phase noise performance is achieved, but the solution in the second prior art adopts a dual-core structure. Compared with the single-core structure, the dual-core structure VCO has larger power consumption and area. In addition, the structure has higher design requirements for the output frequency selector, has certain design difficulties, and has higher power consumption.

[0054] In order 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 adopts an 8-shaped transformer load switch inductor for the first time, and expands the output frequency adjustment range of the single-core LC_VCO through the transformer load switch technology. The 8-shaped inductor effectively solves the problem of serious frequency disturbance caused by electromagnetic interference to the external circuit module. In addition, the present invention can achieve a frequency adjustment range of more than 50% in the case of single-core dual-mode, which has a wider frequency adjustment range than other single-core LC_VCOs, and has a smaller area and lower power consumption than other multi-core multi-mode LC_VCOs.

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

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

[0057] Switch capacitor array 2, transformer load switch inductor 1, variable capacitor 3 and cross-coupled tube 4;

[0058] Two ends of the transformer load switch inductor 1 are respectively connected to two ends of the switch capacitor array 2, and the transformer load switch inductor 1 is connected in parallel with the switch capacitor array 2;

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

[0060] like Figure 6 As shown, the voltage controlled oscillator is mainly composed of four parts: an 8-shaped transformer load switch inductor 1, a switch capacitor array 2 (Capbank), a variable capacitor 3, and a cross-coupled tube 4.

[0061] Among them, the cross-coupled transistor 4 is mainly composed of two MOS transistors M1 and M2, which provide negative resistance for the circuit. m R p ≥1, the oscillator start-up condition is met. m is the cross-coupled tube gain coefficient, R p Parasitic resistance in parallel with the resonant cavity.

[0062] Variable capacitor 3 is composed of Figure 6 The two Cs in V When the control voltage V CTRL When the capacitance C V The capacitance value of LC_VCO decreases. This will increase the output frequency of LC_VCO.

[0063] In the transformer load switch voltage controlled oscillator, the first end of the transformer load switch inductor 1 is connected to the first end of the switch capacitor array 2, and the second end of the transformer load switch inductor 1 is connected to the second end of the switch capacitor array 2. V The second ports of the two varactors C are connected to each other. V The first port of is respectively connected to the first port and the second port of the switch capacitor array 2. The gate of the NMOS tube M1 and the drain of the NMOS tube M2 are commonly connected to the first port of the transformer load switch, the drain of the NMOS tube M1 and the gate of the NMOS tube M2 are commonly connected to the second port of the transformer load switch, and the sources of the two NMOS are connected to the ground.

[0064] Figure 6 The ultra-wideband voltage-controlled oscillator circuit includes: a switch capacitor array, a transformer load switch inductor, a variable capacitor and a cross-coupled tube; the two ends of the transformer load switch inductor are respectively connected to the two ends of the switch capacitor array, and the transformer load switch inductor is connected in parallel with the switch capacitor array; the two ends of the switch capacitor array are respectively connected to a variable capacitor, and the variable capacitor is connected to the cross-coupled tube. The solution in the present invention adopts an 8-shaped transformer load switch inductor for the first time, and expands the output frequency adjustment range of the single-core voltage-controlled oscillator through the transformer load switch technology. The use of the 8-shaped inductor solves the problem of serious frequency disturbance caused by electromagnetic interference to the external circuit module. Compared with other single-core LC_VCOs, it has a wider frequency adjustment range, and compared with other multi-core multi-mode LC_VCOs, it has a smaller area and lower power consumption.

[0065] based on Figure 6 The present specification also provides some specific implementation schemes of the structure, which are described below.

[0066] An example of a basic unit of a switched capacitor array 2 (Capbank) is Figure 7 As shown in FIG. 1 , when the switch SW[N:0] is controlled, the number of capacitors incorporated into the LC_VCO resonant cavity is controlled by the N+1-bit digital signal. In a single basic capacitor unit, when SW is low, the capacitance incorporated into the resonant cavity is C DM When the SW signal is high, the capacitance C DM ||C gs , C gs It is the parasitic capacitance of the switching MOS tube in the basic unit.

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

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

[0069] Figure 8 When current flows through the 8-shaped inductor, the magnetic flux lines in the lower cavity are in the opposite direction to the magnetic flux lines in the upper cavity. Therefore, for an ideal symmetrical 8-shaped inductor, the contribution of the magnetic flux to the outside world is zero, and it will not cause electromagnetic interference to other peripheral modules.

[0070] and Figure 8 The simplified model of the transformer load switch inductance is as follows: Fig. 9 As shown, based on Fig. 9 The simplified model in can be used to calculate the relevant parameter values ​​of the transformer load switch inductance:

[0071] L eff ≈(1-k 2 )L1 (1)

[0072]

[0073]

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

[0075] In order to further illustrate the beneficial effects of the technical solution of the present invention, the following is an explanation by way of example:

[0076] Take the LC_VCO designed with an output frequency adjustment range of more than 50% using TSMC 28nm CMOS process as an example. The 8-shaped transformer load switch inductor is IND20G_V6 and uses the M9 thick metal layer as the primary coil. To obtain a higher total quality factor Q eff . Using M8 and AP layer metal to make two turns of secondary coils that can be controlled by switches, after simulation, the invention realizes an output frequency from 12.66GHz to 25.5GHz, and the LC_VCO using the architecture of the present invention has higher phase noise performance. When the output frequency is 24GHz, the power consumption is 5.4mW. The phase noise is -107.46dBc / Hz at a frequency of 1MHz. When the scheme of the present invention is used for simulation, the simulation result data under the three modes are set as follows: Mode 1 can cover a range of 12.64GHz to 20.19GHz; Mode 2 frequency coverage range is 13.84GHz to 23.74GHz; Mode 3 frequency coverage range is 16.14GHz to 25.44GHz. Combining the three modes, it can be seen that the voltage-controlled oscillator can achieve a maximum frequency of 25.44GHz, a minimum frequency of 12.64GHz, and a center frequency of 19.04GHz. The frequency adjustment range (Tuning Range) calculation formula is:

[0077] Frequency adjustment range = (maximum output frequency - minimum output frequency) / center frequency;

[0078] By bringing the highest output frequency, the lowest output frequency and the center frequency into the frequency adjustment range calculation formula, it can be obtained that the frequency adjustment range of the voltage controlled oscillator is 67%.

[0079] Therefore, the present invention proposes a single-core low phase noise LC_VCO with an ultra-wide frequency adjustment range. This voltage-controlled oscillator uses an 8-shaped transformer load switch inductor for the first time, and expands the output frequency adjustment range of the single-core LC_VCO through transformer load switch technology. The use of the 8-shaped inductor effectively solves the problem of serious frequency disturbance caused by electromagnetic interference to external circuit modules. Compared with other single-core LC_VCOs, it has a wider frequency adjustment range, and compared with other multi-core multi-mode LC_VCOs, it has a smaller area and lower power consumption. More specifically, the present invention can achieve a frequency adjustment range of more than 50% in the case of single-core dual-mode.

[0080] Although the present invention is described herein in conjunction with various embodiments, in the process of implementing the claimed invention, those skilled in the art may understand and implement 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 "one" or "an" does not exclude multiple situations. A single processor or other unit may implement several functions listed in the claims. Certain measures are recorded in 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 conjunction with specific features and embodiments thereof, it is apparent that various modifications and combinations may be made thereto without departing from the spirit and scope of the present invention. Accordingly, this specification and the accompanying drawings are merely exemplary illustrations of the present invention as defined by the appended claims and are deemed to cover any and all modifications, variations, combinations or equivalents within the scope of the present invention. Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, the present invention is intended to include such modifications and variations if they fall within the scope of the claims of the present invention and their equivalents.

Claims

1. An ultra-wideband voltage-controlled oscillator circuit, characterized in that: The circuit includes: Switched capacitor arrays, transformer load switch inductors, variable capacitors, and cross-coupled transistors; The two ends of the transformer load switch inductor are respectively connected to the two ends of the switch capacitor array, and the transformer load switch inductor is connected in parallel with the switch capacitor array; Two ends of the switch capacitor array are respectively connected to a variable capacitor, and the variable capacitor is connected to the cross-coupling tube.

2. The ultra-wideband voltage-controlled oscillator circuit according to claim 1, characterized in that: The cross-coupled transistor includes a first MOS transistor and a second MOS transistor; The gate of the first MOS tube and the drain of the second MOS tube are commonly connected to one end of the transformer load switch inductor, the drain of the first MOS tube and the gate of the second MOS tube are commonly connected to the other end of the transformer load switch inductor, and the source of the first MOS tube and the source of the second MOS tube are both connected to the ground.

3. The ultra-wideband voltage-controlled oscillator circuit according to claim 1, characterized in that: The transformer load switch inductor is an 8-shaped transformer load switch inductor.

4. 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; the first port of the first capacitor is connected to one end of the switch capacitor array, and the first port of the second capacitor is connected to the other end of the switch capacitor array; the second port of the first capacitor is connected to the second port of the second capacitor.

5. The ultra-wideband voltage-controlled oscillator circuit according to claim 1, characterized in that: The transformer load switch inductor includes a primary coil and a secondary coil, wherein the secondary coil surrounds the primary coil in a figure eight shape.

6. The ultra-wideband voltage-controlled oscillator circuit according to claim 5, characterized in that: The primary coil is the thickest metal layer in the voltage-controlled oscillator circuit; the secondary coil is the other metal layer except the primary coil.

7. The ultra-wideband voltage-controlled oscillator circuit according to claim 1, characterized in that: A simplified model based on the transformer load switch inductance uses the formula: Calculate the relevant parameter values ​​of the transformer load switch inductance; Among them, L eff is the total inductance of the transformer load switch inductor, R eff is the parasitic resistance of the transformer load switch inductor, Q eff is the primary inductance quality factor Q value of the transformer load switch inductor, L1 is the primary coil inductance, L2 is the secondary coil inductance, k is the coupling coefficient between the primary coil and the secondary coil, R2 is the parasitic resistance of the secondary coil, and ω represents the angular frequency.

8. The ultra-wideband voltage-controlled oscillator circuit according to claim 1, characterized in that: The transformer load switch inductor increases the output frequency adjustment range of the single-core voltage-controlled oscillator through the transformer load switch technology.

9. The ultra-wideband voltage-controlled oscillator circuit according to claim 2, characterized in that: The cross-coupled transistor is used to provide negative resistance for the ultra-wideband voltage-controlled oscillator circuit. m R p ≥1, the oscillator start-up condition is met; where g m is the pair gain coefficient of the cross-coupled tube, R p Parasitic resistance in parallel with the resonant cavity.

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