A high-precision eight-phase voltage-controlled oscillator based on an inductance multiplexing coupling network

Abstract

This invention provides a high-precision eight-phase voltage-controlled oscillator (VCO) based on an inductor-multiplexed coupling network. The structure includes four VCO circuit units with complementary cross-coupling and an eight-phase inductor-multiplexed coupling network. Eight identical inductors are connected end-to-end to form the inductor-multiplexed coupling network. The resonant cavity inductance of the four oscillator circuit units is replaced by the equivalent inductance connected to the inductor-multiplexed coupling network. Each of the four oscillator cores outputs two differential signals, resulting in a total of eight output signals. The oscillator units generate eight-phase signals through the coupling effect of the coupling network. In this design, the eight-phase inductor-multiplexed coupling network has high symmetry, thus the 2π phase is uniformly distributed in each VCO, achieving high phase accuracy output. Furthermore, since the inductor-multiplexed coupling network is part of the oscillator resonant cavity, no additional coupling network area is required, significantly saving chip area compared to traditional LC multiphase VCOs.

Description

Technical Field

[0001] This invention belongs to the field of microelectronics technology and relates to a high-precision eight-phase voltage-controlled oscillator based on an inductor multiplexing coupling network. Background Technology

[0002] Many key technologies in communication systems, such as clock data recovery (CDR), quadrature modulation (I / Q modulation), and phase shift keying (PSK), rely on precise multiphase signals. Multiphase voltage-controlled oscillators (VCOs) can directly generate multiphase clock signals with low phase noise and high phase accuracy, and have been widely used in wired and wireless communications.

[0003] A voltage-controlled oscillator (VCO) is a device that controls the frequency of an output signal using a voltage signal, providing a signal source of a specific frequency. A multiphase VCO consists of multiple single-core VCOs and a multiphase coupling network. The multiphase coupling network performs phase distribution on the signal from the multi-core VCOs, thereby achieving multiphase output.

[0004] Multiphase coupling not only enables the output of multiphase signals but also significantly reduces phase noise, making it a key technology for generating high-quality signal sources. A multiphase coupling network is a circuit structure that connects multiple single-core oscillator units and establishes a phase distribution among the oscillator output signals, forcing a fixed phase relationship between the multiple oscillating signals. However, current high-frequency multiphase coupling networks suffer from various problems, such as capacitive coupling networks limiting the tuning range, poor stability of superharmonic coupling networks, and high area cost of microstrip line coupling networks. Therefore, developing multiphase coupling networks with small area and high phase accuracy is crucial for realizing high-performance multiphase voltage-controlled oscillators. Summary of the Invention

[0005] The purpose of this invention is to provide a high-precision eight-phase voltage-controlled oscillator based on an inductor multiplexing coupling network to solve the above-mentioned technical problems.

[0006] To solve the above-mentioned technical problems, the specific technical solution of the present invention for a high-precision eight-phase voltage-controlled oscillator based on an inductor multiplexing coupling network is as follows: A high-precision eight-phase voltage-controlled oscillator based on an inductor multiplexing coupling network includes: Four voltage-controlled oscillator units, each of which outputs a pair of differential oscillation signals, generating a total of eight output signals; An inductor multiplexed eight-phase coupled network consists of eight inductor units connected end to end to form a closed loop. In this embodiment, the resonant cavity inductance of each voltage-controlled oscillator unit is replaced by the equivalent inductance of the inductor multiplexing eight-phase coupling network, and the eight output signals are coupled through the inductor multiplexing eight-phase coupling network to achieve a redistribution of the output signal phase.

[0007] Furthermore, the eight output signals include output signals Vout1+, Vout1-, Vout2+, Vout2-, Vout3+, Vout3-, Vout4+, and Vout4-, wherein output signals Vout1+ and Vout1-, Vout2+ and Vout2-, Vout3+ and Vout3-, and Vout4+ and Vout4- are differential signals.

[0008] Furthermore, the voltage-controlled oscillator unit includes NMOS transistor M1, NMOS transistor M2, PMOS transistor M3, and PMOS transistor M4; The sources of NMOS transistors M1 and M2 are grounded. The gate of NMOS transistor M1 is connected to the drain of NMOS transistor M2 and connected to the output signal Vout-. The gate of NMOS transistor M2 is connected to the drain of NMOS transistor M1 and connected to the output signal Vout+. The sources of PMOS transistors M3 and M4 are connected to the power supply VDD. The gate of PMOS transistor M3 is connected to the drain of PMOS transistor M4 and is connected to the output signal Vout-. The gate of PMOS transistor M4 is connected to the drain of PMOS transistor M3 and is connected to the output signal Vout+.

[0009] Furthermore, the NMOS transistors M1 and M2, as well as the PMOS transistors M3 and M4, form cross-coupled pairs to generate negative resistance and offset the losses of the resonant cavity.

[0010] Furthermore, the resonant cavity of the voltage-controlled oscillator unit is composed of an equivalent inductance Leq connected by an inductor multiplexing coupling network and varactor transistors Cvar1 and Cvar2. One end of the equivalent inductance Leq is connected to the gate of varactor transistor Cvar1 and the output signal Vout+, and the other end is connected to the gate of varactor transistor Cvar2 and the output signal Vout-. The source and drain of varactor transistors Cvar1 and Cvar2 are connected and then connected to a potential signal Vctrl. The oscillation frequency of the output signal of the voltage-controlled oscillator unit is directly determined by the resonant frequency of the resonant cavity. The voltage-controlled oscillator unit controls the magnitude of the potential signal Vctrl to change the size of the equivalent capacitance of varactor transistors Cvar1 and Cvar2 connected in series, thereby fine-tuning the oscillation frequency of the output signal.

[0011] Furthermore, the eight inductor units include inductors L1, L2, L3, L4, L5, L6, L7, and L8. The four voltage-controlled oscillator units include voltage-controlled oscillator unit one, voltage-controlled oscillator unit two, voltage-controlled oscillator unit three, and voltage-controlled oscillator unit four, whose differential output signals are output signals Vout1+ and Vout1-, output signals Vout2+ and Vout2-, output signals Vout3+ and Vout3-, and output signals Vout4+ and Vout4-, respectively. Inductor L1 connects to output signals Vout1+ and Vout2+, coupling them together. Inductor L2 connects to output signals Vout2+ and Vout3+, coupling them together. Inductor L3 connects to output signals Vout3+ and Vout4+, coupling them together. Inductor L4 connects to output signals Vout4+ and Vout1-, coupling them together. Inductor L5 connects to output signals Vout1- and Vout2-, coupling them together. Inductor L6 connects to output signals Vout2- and Vout3-, coupling them together. Inductor L7 connects to output signals Vout3- and Vout4-, coupling them together. Inductor L8 connects to output signals Vout4- and Vout1+, coupling them together.

[0012] Furthermore, the structure of the inductor multiplexing eight-phase coupling network is completely symmetrical, so that the 2π phase is evenly distributed among the eight inductor units, thereby achieving a phase difference of 45° between adjacent output signals in the eight output signals.

[0013] Furthermore, the eight inductor units are identical inductors.

[0014] Furthermore, the voltage-controlled oscillator unit adopts a complementary cross-coupling structure. Beneficial effects: (1) The inductance and coupling network of the traditional multi-phase LC voltage-controlled oscillator resonant network occupy a large chip area; the inductor multiplexing multi-phase coupling network involved in this invention uses the inductor loop to achieve precise phase distribution and realize multi-phase VCO structure; at the same time, it cleverly utilizes the phase relationship between the output signals of each VCO to multiplex the inductors in the resonant cavity of the voltage-controlled oscillator unit, which greatly reduces the area occupied by the multi-phase LC-VCO chip.

[0015] (2) The eight-phase voltage-controlled oscillator described in this invention uses a fully symmetrical inductor multiplexing coupling network. On the one hand, it can make the output signal phase evenly distributed and realize a high-precision phase difference between each output signal. On the other hand, it can greatly reduce the signal amplitude difference between each output terminal.

[0016] (3) This invention achieves an integrated design of resonance and coupling, eliminating redundant components. Traditional eight-phase voltage-controlled oscillators separate the resonant cavity inductor from the coupling network, which requires additional chip area and introduces parasitic effects. This invention uses inductor multiplexing technology to make the inductor unit in the coupling network serve as the equivalent inductor of the resonant cavity of each voltage-controlled oscillator unit, structurally ensuring the synchronization of the resonant frequency and the coupling phase, and improving the phase stability of the output signal.

[0017] (4) This invention uses an inductor as a coupling element and utilizes the inherent phase relationship between the current and voltage across the inductor to form a natural current loop in the coupling network, which has good robustness to process deviations, temperature changes and power supply fluctuations. Under the same process deviation conditions, the phase error of the inductive coupling network is much smaller than that of the traditional capacitive coupling network, which is especially advantageous in high-frequency applications.

[0018] (5) The present invention has a simple structure and strong symmetry, requiring no additional active devices or complex control circuits, and is easy to implement in standard CMOS process. At the same time, the coupling network and the resonant cavity share a passive inductor, which significantly reduces the circuit area and meets the requirements of high-frequency communication chips for miniaturization and high integration. It is suitable for sub-rate clock data recovery circuits, phased array systems and multiphase local oscillators. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the circuit structure of the eight-phase voltage-controlled oscillator of the present invention; Figure 2 for Figure 1 Schematic diagram of the medium-voltage controlled oscillator unit; Figure 3 for Figure 1 A schematic diagram of the structure of an eight-phase coupled inductor multiplexing network. Detailed Implementation

[0020] The invention will now be further explained with reference to the accompanying drawings.

[0021] like Figure 1As shown, a high-precision eight-phase voltage-controlled oscillator (VCO) based on an inductor multiplexing coupling network includes four VCO units and an inductor multiplexing coupling network containing eight identical inductors. The resonant cavity inductance of each VCO unit is replaced by an equivalent inductance connected to the inductor multiplexing coupling network. The four VCO units self-oscillate and output differential signals, resulting in a total of eight output signals: Vout1+, Vout1-, Vout2+, Vout2-, Vout3+, Vout3-, Vout4+, and Vout4-. Vout1+ and Vout1-, Vout2+ and Vout2-, Vout3+ and Vout3-, and Vout4+ and Vout4- are differential signals. These output signals are coupled through the inductor multiplexing network, with a 2π phase evenly distributed among the inductors, generating an eight-phase output signal with a phase difference of 45°.

[0022] like Figure 2 As shown, the voltage-controlled oscillator (VCO) unit in the eight-phase VCO is implemented based on a cross-coupled structure of PMOS and NMOS transistors. The VCO unit generates oscillation signals Vout+ and Vout-, and includes NMOS transistors M1 and M2, PMOS transistors M3 and M4, the equivalent inductance Leq of the inductor multiplexing coupling network, and varactor transistors Cvar1 and Cvar2. The sources of NMOS transistors M1 and M2 are grounded. The gate of NMOS transistor M1 is connected to the drain of NMOS transistor M2 and then to the output Vout-, while the gate of NMOS transistor M2 is connected to the drain of NMOS transistor M1 and then to the output Vout+. The sources of PMOS transistors M3 and M4 are connected to the power supply VDD. The gate of PMOS transistor M3 is connected to the drain of PMOS transistor M4 and then to the output Vout-, while the gate of PMOS transistor M4 is connected to the drain of PMOS transistor M3 and then to the output Vout+. NMOS transistors M1 and M2, and PMOS transistors M3 and M4, respectively form cross-coupled pairs, generating negative resistance to offset the resonant cavity losses. The resonant cavity of the voltage-controlled oscillator (VCO) unit consists of an equivalent inductance Leq connected via an inductor multiplexing coupling network and varactor transistors Cvar1 and Cvar2. One end of the equivalent inductance Leq of the coupling network is connected to the gate of varactor transistor Cvar1 and the output Vout+, and the other end is connected to the gate of varactor transistor Cvar2 and the output Vout-. The source and drain of Cvar1 and Cvar2 are connected to a potential signal Vctrl. The oscillation frequency of the output signal of the VCO unit is directly determined by the resonant frequency of the resonant cavity. The VCO unit of this invention controls the magnitude of the potential signal Vctrl to change the size of the equivalent capacitance of the varactor transistors Cvar1 and Cvar2 connected in series, thereby fine-tuning the oscillation frequency of the output signal.

[0023] like Figure 3As shown, eight identical inductors L1, L2, L3, L4, L5, L6, L7, and L8 of the inductor multiplexing coupling network are connected end to end in sequence. The four voltage-controlled oscillator (VCO) units include VCO unit 1, VCO unit 2, VCO unit 3, and VCO unit 4. VCO unit 1 generates differential oscillation signals Vout1+ and Vout1-, VCO unit 2 generates differential oscillation signals Vout2+ and Vout2-, VCO unit 3 generates differential oscillation signals Vout3+ and Vout3-, and VCO unit 4 generates differential oscillation signals Vout4+ and Vout4-. The signal terminals are coupled via inductors: output signals Vout1+ and Vout2+ are coupled through inductor L1; output signals Vout2+ and Vout3+ are coupled through inductor L2; output signals Vout3+ and Vout4+ are coupled through inductor L3; output signals Vout4+ and Vout1- are coupled through inductor L4; output signals Vout1- and Vout2- are coupled through inductor L5; output signals Vout2- and Vout3- are coupled through inductor L6; output signals Vout3- and Vout4- are coupled through inductor L7; and output signals Vout4- and Vout1+ are coupled through inductor L8. Due to the symmetry of the structure, the 2π phase is evenly distributed within the coupling network loop, realizing the eight-phase coupling function where each output signal is 45° phase with the adjacent output signal.

[0024] Compared with traditional high-frequency eight-phase voltage-controlled oscillators, the high-precision eight-phase voltage-controlled oscillator based on an inductor multiplexing coupling network of this invention has the following advantages: ① The multi-phase coupling network used in traditional eight-phase voltage-controlled oscillators cannot basically replace the passive inductor part of the resonant cavity, requiring additional chip area; while the inductor multiplexing eight-phase coupling network used in this invention performs phase coupling while replacing the resonant cavity inductor in the traditional structure, incorporating the resonant cavity inductor of the voltage-controlled oscillator as part of the inductor multiplexing network, without requiring additional coupling network area. ② The inductor multiplexing coupling network uses eight identical inductor units, so that the phase is evenly divided into eight parts in space, that is, the phase difference between adjacent output signals is 45°, with extremely small error.

[0025] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-precision eight-phase voltage-controlled oscillator based on an inductor multiplexing coupling network, characterized in that, include: Four voltage-controlled oscillator units, each of which outputs a pair of differential oscillation signals, generating a total of eight output signals; An inductor multiplexed eight-phase coupled network consists of eight inductor units connected end to end to form a closed loop. In this configuration, the resonant cavity inductance of each voltage-controlled oscillator unit is replaced by the equivalent inductance of the inductor multiplexing eight-phase coupling network. The eight output signals are coupled through the inductor multiplexing eight-phase coupling network to achieve a redistribution of the output signal phase. The eight output signals include output signals Vout1+, Vout1-, Vout2+, Vout2-, Vout3+, Vout3-, Vout4+, and Vout4-, wherein output signals Vout1+ and Vout1-, Vout2+ and Vout2-, Vout3+ and Vout3-, and Vout4+ and Vout4- are differential signals. The resonant cavity of the voltage-controlled oscillator (VCO) unit is composed of an equivalent inductance Leq connected by an inductor multiplexing coupling network and varactor transistors Cvar1 and Cvar2. One end of the equivalent inductance Leq is connected to the gate of varactor transistor Cvar1 and the output signal Vout+, and the other end is connected to the gate of varactor transistor Cvar2 and the output signal Vout-. The source and drain of each varactor transistor Cvar1 and Cvar2 are connected to a potential signal Vctrl. The oscillation frequency of the output signal of the VCO unit is directly determined by the resonant frequency of the resonant cavity. The VCO unit controls the magnitude of the potential signal Vctrl to change the size of the equivalent capacitance of varactor transistors Cvar1 and Cvar2 connected in series, thereby fine-tuning the oscillation frequency of the output signal. The eight inductor units include inductors L1, L2, L3, L4, L5, L6, L7, and L8. The four voltage-controlled oscillator units include voltage-controlled oscillator unit one, voltage-controlled oscillator unit two, voltage-controlled oscillator unit three, and voltage-controlled oscillator unit four, whose differential output signals are output signals Vout1+ and Vout1-, output signals Vout2+ and Vout2-, output signals Vout3+ and Vout3-, and output signals Vout4+ and Vout4-, respectively. Inductor L1 is connected between output signals Vout1+ and Vout2+ for coupling; inductor L2 is connected between output signals Vout2+ and Vout3+ for coupling; inductor L3 is connected between output signals Vout3+ and Vout4+ for coupling; inductor L4 is connected between output signals Vout4+ and Vout1- for coupling; inductor L5 is connected between output signals Vout1- and Vout2- for coupling; inductor L6 is connected between output signals Vout2- and Vout3- for coupling; inductor L7 is connected between output signals Vout3- and Vout4- for coupling; and inductor L8 is connected between output signals Vout4- and Vout1+ for coupling. The structure of the inductor multiplexing eight-phase coupling network is completely symmetrical, so that the 2π phase is evenly distributed among the eight inductor units, thereby achieving a phase difference of 45° between adjacent output signals in the eight output signals. The eight inductor units are the same type of inductor; The voltage-controlled oscillator unit adopts a complementary cross-coupling structure.

2. The high-precision eight-phase voltage-controlled oscillator based on an inductor multiplexing coupling network according to claim 1, characterized in that, The voltage-controlled oscillator unit includes NMOS transistor M1, NMOS transistor M2, PMOS transistor M3 and PMOS transistor M4; The sources of NMOS transistors M1 and M2 are grounded. The gate of NMOS transistor M1 is connected to the drain of NMOS transistor M2 and connected to the output signal Vout-. The gate of NMOS transistor M2 is connected to the drain of NMOS transistor M1 and connected to the output signal Vout+. The sources of PMOS transistors M3 and M4 are connected to the power supply VDD. The gate of PMOS transistor M3 is connected to the drain of PMOS transistor M4 and is connected to the output signal Vout-. The gate of PMOS transistor M4 is connected to the drain of PMOS transistor M3 and is connected to the output signal Vout+.

3. The high-precision eight-phase voltage-controlled oscillator based on an inductor multiplexing coupling network according to claim 2, characterized in that, The NMOS transistors M1 and M2, as well as the PMOS transistors M3 and M4, form cross-coupled pairs, generating negative resistance to offset the losses in the resonant cavity.

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