Windmill type coupling series resonance voltage-controlled oscillator based on F-type inductance network

Abstract

The invention discloses a windmill type coupling series resonance voltage-controlled oscillator based on an F-type inductance network. The windmill type coupling series resonance voltage-controlled oscillator comprises four oscillator cores which are arranged in a windmill shape in a rotational symmetry mode. The four oscillator cores are connected in series end to end, each oscillator core comprises a passive F-type inductance network and an active phase inverter unit, and in the same oscillator core, the output end of the F-type inductance network is connected with the input end of the phase inverter unit; the F-type inductance network comprises an input end, a first inductor, a second inductor, a third inductor, a fourth inductor, a frequency tuning unit and an output end. According to the invention, signal output with low phase noise is realized under the condition of ensuring the working frequency.

Description

Technical Field

[0001] This invention relates to the field of voltage-controlled oscillators, and in particular to a windmill-type coupled series resonant voltage-controlled oscillator based on an F-type inductor network. Background Technology

[0002] Low phase noise local oscillator signals are crucial for millimeter-wave communication systems because they play a key role in determining the error vector amplitude of high-order quadrature amplitude modulation (QAM) schemes, which are widely used to achieve high data rates. Therefore, generating a gigahertz-level local oscillator signal with high spectral purity is of great practical significance.

[0003] Traditional multi-core parallel resonant voltage-controlled oscillators (VCOs) have demonstrated the ability to significantly reduce phase noise, albeit at the cost of increased chip area and power consumption. However, their performance is often degraded by unavoidable inter-core mismatch. Furthermore, optimizing the FoM (FoM) typically requires operation at non-standard voltage levels, which complicates power management design and system-level integration. Series resonant VCOs offer an alternative for achieving low phase noise. Thanks to the low equivalent resistance of the LC resonant cavity, they can achieve significantly improved phase noise without relying on multiple oscillator cores. However, the operating frequency of series resonant VCOs is significantly reduced due to the substantial parasitic capacitance of the large transistors used. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a windmill-type coupled series resonant voltage-controlled oscillator based on an F-type inductor network, which achieves low phase noise signal output while ensuring the operating frequency.

[0005] The objective of this invention is achieved through the following technical solution: a windmill-type coupled series resonant voltage-controlled oscillator based on an F-type inductor network, comprising four oscillator cores arranged in a windmill shape in a rotationally symmetrical manner;

[0006] The four oscillator cores are connected in series. Each oscillator core includes a passive F-type inductor network and an active inverter unit. In the same oscillator core, the output terminal of the F-type inductor network is connected to the input terminal of the inverter unit.

[0007] The F-type inductor network includes an input terminal, a first inductor, a second inductor, a third inductor, a fourth inductor, a frequency tuning unit, and an output terminal. The first end of the first inductor is connected to the output terminal, and the second end of the first inductor is connected to the output terminal through the third inductor. The first end of the second inductor is connected between the first inductor and the third inductor, and the second end of the second inductor is connected to the tuning voltage through the frequency tuning unit. The first end of the fourth inductor is connected between the third inductor and the output terminal, and the second end of the fourth inductor is grounded.

[0008] Furthermore, the four oscillator cores are identical; the four oscillator cores are connected in series end to end as follows: the output terminal of the inverter unit of the first oscillator core is connected to the input terminal of the F-type inductor network of the second oscillator core; the output terminal of the inverter unit of the second oscillator core is connected to the input terminal of the F-type inductor network of the third oscillator core; the output terminal of the inverter unit of the third oscillator core is connected to the input terminal of the F-type inductor network of the fourth oscillator core; and the output terminal of the inverter unit of the fourth oscillator core is connected to the input terminal of the F-type inductor network of the first oscillator core.

[0009] The F-type inductor network has parasitic capacitance at both its input and output terminals, which is equivalent to grounding capacitance.

[0010] Furthermore, the frequency tuning unit includes a first varactor diode and a second varactor diode. The first end of the first varactor diode is connected to the first end of the second varactor diode, and the common point of connection is connected to the second end of the second inductor. The second end of the first varactor diode is connected to a tuning voltage V. T1 The second terminal of the second varactor is connected to a tuning voltage V. T2 This enables control of the first and second variable capacitance tubes.

[0011] Furthermore, the inverter unit includes a resistor R and a PMOS transistor M. P and NMOS transistor M N The PMOS transistor M P The source of the PMOS transistor is connected to the VDD power supply. P The drain of the NMOS transistor M N The drain of the PMOS transistor is connected to the first common point. P The gate of the NMOS transistor M N The gate of the NMOS transistor is connected to the second common point. N The source of the inverter is grounded; the resistor R is connected between the first common point and the second power supply point; the first common point serves as the input terminal of the inverter unit, and the second common point serves as the output terminal of the inverter unit.

[0012] The beneficial effects of this invention are: 1. The series resonant voltage-controlled oscillator based on F-type inductor network windmill coupling overcomes the low-frequency limitation of traditional series resonant voltage-controlled oscillators and achieves stable oscillation at 40 GHz. This design exhibits low phase noise. Furthermore, the series resonant voltage-controlled oscillator (SR-VCO) enhances robustness to inter-stage mismatch within the core through windmill coupling and avoids reliability issues related to excessive gate swing through inductor voltage division technology.

[0013] 2. Considering that parasitic capacitance will reduce the operating frequency, in order to reduce the impact of this parasitic capacitance on the operating frequency, a parallel inductor is added to form an LC parallel network. By adjusting the value of the inductor, it presents an equivalent capacitance value smaller than the parasitic capacitance at the operating frequency, thereby reducing the impact of large parasitic capacitance on the frequency. Attached Figure Description

[0014] Figure 1 This is a schematic diagram illustrating the principle of the present invention;

[0015] Figure 2 This is a schematic diagram of an F-type inductor network.

[0016] Figure 3 This is a schematic diagram illustrating the effect of adjusting the inductance on an F-type inductor network.

[0017] Figure 4 This diagram illustrates how frequency mismatch can be simulated by changing the parasitic capacitance values ​​of two adjacent stages (the first and second stages). Detailed Implementation

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0019] The series resonant voltage-controlled oscillator proposed in this invention consists of four identical cores arranged in a windmill shape with rotational symmetry, such as... Figure 1 As shown. Each core contains a passive F-type inductor network and an active inverter unit. The inverter is composed of a PMOS transistor M. P (128μm / 40 nm) and NMOS transistor M N It consists of a (64μm / 40 nm) diode and a resistor R (9kΩ). Frequency tuning is achieved through a varactor transistor C. V This is achieved by two sets of tuning voltages V. T1 and V T2 The control is composed of a variable capacity tube.

[0020] To overcome the limitations of transformer coupling on high-frequency modes, this invention introduces an F-type inductor network. For example... Figure 2 As shown, the passive part of each core is a component consisting of an inductor L.1,sn L 2,sn L 3,sn and L 4,sn The F-type network formed by this, along with the drain parasitic capacitance (C) of the transistor, P,D ) and gate parasitic capacitance (C P,G They work together. The structure is named after the fact that the arrangement of the four inductors resembles the letter "F".

[0021] The key to this network is ensuring stable operation of the circuit in high-frequency mode. This is achieved by reducing L... 1,sn (L1) can effectively enhance the resonant peak value of high-frequency modes, ensuring stable oscillation, such as Figure 3 As shown in (a) of the diagram. L 2,sn (L2) and L 3,sn Setting (L3) to 330 pH allows the resonant frequency to be aligned with the 40 GHz target frequency band while maintaining a reasonable inductance quality factor (Q value). Furthermore, setting L... 2,sn and L 3,sn Setting them to the same value facilitates the coupling of the windmill shape.

[0022] Even in high-frequency mode, large parasitic capacitance still limits the achievable oscillation frequency. P,G The capacitor is a parasitic capacitance, which can be quite large and reduce the operating frequency. To minimize the impact of this parasitic capacitance on the operating frequency, a parallel inductor is added. This inductor can be connected in parallel with the capacitor, forming an LC parallel network. By choosing an appropriate value for the inductor, it can be made to exhibit a capacitance greater than that of the capacitor at the operating frequency. P,G A smaller equivalent capacitance value reduces the impact of a large capacitor on frequency; therefore, compared with C P,G parallel L 4,sn It can be used to compensate for its parasitic effects, thereby adjusting the equivalent capacitive reactance of the resonant cavity at the operating frequency. For example... Figure 3 As shown in (b), decrease L 4,sn (L4) can increase the resonant frequency of the high-frequency mode. Ultimately, L... 4,sn It was optimized to 160 pH to strike a balance between increasing the frequency and maintaining sufficient peak amplitude of the high-frequency mode.

[0023] The windmill-type inductor network proposed in this invention aims to suppress mismatch between stages within the core. Specifically, it consists of four stages (each stage being an oscillator core). Due to manufacturing processes, the stages may have different equivalent inductance and capacitance values. Therefore, each stage may ideally operate at a different frequency. The mutual attraction and locking between stages ultimately cause the entire network to operate at a frequency point deviating from the ideal oscillation frequency of each stage. This mismatch-induced deviation deteriorates the equivalent Q value and phase noise. By increasing the coupling between stages, the connection between stages can be strengthened, thereby mitigating the impact of mismatch on phase noise; for example... Figure 1 As shown, the windmill-shaped coupling improves area efficiency and enhances robustness by introducing well-designed intracore magnetic coupling. Specifically, the inductor L of the nth stage... 3,sn With the previous stage inductor L 2,sn-1 (coupling coefficient k) 32 =0.4) and the inductance L of the next stage 4,sn+1 (coupling coefficient k) 43 =0.4) to form magnetic coupling. These coupling coefficients are designed based on practically achievable layout structures, and electromagnetic simulations confirm that they provide a balance between mismatch suppression and layout complexity.

[0024] like Figure 4 As shown in (a), frequency mismatch is simulated by changing the parasitic capacitance values ​​of two adjacent stages (the first and second stages). This is in contrast to the absence of such coupling (k...). 32 =0,k 43 Compared to the case where k=0), the introduced coupling (k) 32 =0.4,k 43 =0.4) When the frequency mismatch is set to 6% and 12%, the degradation of phase noise is reduced by 7.5 dB and 11.5 dB, respectively.

[0025] It is worth noting that the introduced wind turbine core coupling does not reduce the oscillation frequency of the required high-frequency mode. For example... Figure 4 As shown in (b), add coupling (k) 32 =0.4,k 43 =0.4) Instead, it shifts the resonant frequency of the high-frequency mode to a higher value.

[0026] In series resonant voltage-controlled oscillators (VCOs), the large current flowing through the resonant cavity often generates excessive voltage swing at the transistor gate node, posing a reliability challenge. A traditional approach is to add a capacitor in series with the gate to form a capacitive voltage divider to reduce gate voltage stress. However, introducing such a fixed capacitor may alter the resonant cavity frequency, complicating the design trade-offs.

[0027] This invention employs inductive voltage divider technology to overcome this limitation. For example... Figure 2 In the F-type inductor network shown, using L3,sn and L 4,sn As a voltage divider, the key advantage of this method is that it can be easily changed by altering L. 4,sn To adjust the voltage divider ratio, and simultaneously adjust L 3,sn This method maintains a constant equivalent impedance. Therefore, it can effectively control the gate voltage swing without disturbing the resonant frequency of the series resonant cavity.

[0028] The chip testing performance ultimately achievable by this invention is as follows: This series resonant voltage-controlled oscillator, tuned by two sets of varactor diodes, achieves a continuous frequency tuning range from 38.08 GHz to 42.19 GHz (10.2%). Throughout the tuning range, the phase noise measured at a 10 MHz offset varies from -132.36 dBc / Hz to -129.74 dBc / Hz. Operating at a standard 1 V supply voltage, the circuit consumes 40 mW and corresponds to a factor of quality (FoM) ranging from 188.3 dBc / Hz to 186.0 dBc / Hz, with only a 2.3 dB variation across the entire FTR.

[0029] The foregoing description illustrates and describes a preferred embodiment of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A windmill-type coupled series resonant voltage-controlled oscillator based on an F-type inductor network, characterized in that: It includes four oscillator cores arranged in a windmill shape with rotational symmetry; The four oscillator cores are connected in series. Each oscillator core includes a passive F-type inductor network and an active inverter unit. In the same oscillator core, the output terminal of the F-type inductor network is connected to the input terminal of the inverter unit. The F-type inductor network includes an input terminal, a first inductor, a second inductor, a third inductor, a fourth inductor, a frequency tuning unit, and an output terminal. The first end of the first inductor is connected to the output terminal, and the second end of the first inductor is connected to the output terminal through the third inductor. The first end of the second inductor is connected between the first inductor and the third inductor, and the second end of the second inductor is connected to the tuning voltage through the frequency tuning unit. The first end of the fourth inductor is connected between the third inductor and the output terminal, and the second end of the fourth inductor is grounded.

2. The windmill-type coupled series resonant voltage-controlled oscillator based on an F-type inductor network according to claim 1, characterized in that: The cores of the four oscillators are exactly the same.

3. The windmill-type coupled series resonant voltage-controlled oscillator based on an F-type inductor network according to claim 1, characterized in that: The four oscillator cores being connected in series means that: the output of the inverter unit of the first oscillator core is connected to the input of the F-type inductor network of the second oscillator core; the output of the inverter unit of the second oscillator core is connected to the input of the F-type inductor network of the third oscillator core; the output of the inverter unit of the third oscillator core is connected to the input of the F-type inductor network of the fourth oscillator core; and the output of the inverter unit of the fourth oscillator core is connected to the input of the F-type inductor network of the first oscillator core.

4. A windmill-type coupled series resonant voltage-controlled oscillator based on an F-type inductor network according to claim 1, characterized in that: The frequency tuning unit includes a first varactor diode and a second varactor diode. The first terminal of the first varactor diode is connected to the first terminal of the second varactor diode, and the common point of connection is connected to the second terminal of the second inductor. The second terminal of the first varactor diode is connected to a tuning voltage V. T1 The second terminal of the second varactor is connected to a tuning voltage V. T2 This enables control of the first and second variable capacitance tubes.

5. A windmill-type coupled series resonant voltage-controlled oscillator based on an F-type inductor network according to claim 2, characterized in that: The inverter unit includes a resistor R and a PMOS transistor M. P and NMOS transistor M N The PMOS transistor M P The source of the PMOS transistor is connected to the VDD power supply. P The drain of the NMOS transistor M N The drain of the PMOS transistor is connected to the first common point. P The gate of the NMOS transistor M N The gate of the NMOS transistor is connected to the second common point. N The source of the inverter is grounded; the resistor R is connected between the first common point and the second power supply point; the first common point serves as the input terminal of the inverter unit, and the second common point serves as the output terminal of the inverter unit.

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