Phase rotator based on charge injection

Abstract

A phase rotator based on charge injection comprises a pulse generation circuit, and an injection charge generation circuit, a clock phase selection circuit and a counting control circuit which are respectively connected with the pulse generation circuit. The output end of the injection charge generation circuit is connected with the oscillator, and the output clock phase of the oscillator is adjusted by controlling the injection charge quantity, injection time and times; the clock phase selection circuit selects one path of clock and sends the clock back to the pulse generation circuit under the action of a control word according to a multi-phase clock; and the pulse generation circuit is triggered by an enable signal of the clock and counting control circuit, outputs a pulse with adjustable pulse width, drives the injection charge generation circuit to inject charges into the oscillator to complete one-time phase shift, and the counting control circuit controls the injection times to complete output phase adjustment. Charge injection phase modulation is intrinsic linear, static power consumption is avoided, the device can be used for a phase-locked loop, clock data recovery or other phase modulation systems, full-period-range precise phase adjustment is carried out on multiple clocks above GHz, and the precision is set through internal control words.

Description

Technical Field

[0001] This invention relates to a technology in the field of digital clocks, specifically a charge-injection-based phase rotator suitable for phase-locked loops and clock data recovery circuits in wired and wireless communications. Background Technology

[0002] Existing phase rotation techniques mostly employ multi-phase interpolation: introducing a multi-channel voltage / current mode clock driver to convert the clock signal to the voltage / current domain, and using a weighted adder to add the signals in amplitude to achieve phase interpolation. However, because the driver operates continuously at the clock frequency, the power consumption of the multi-channel parallel operation increases significantly. At the same time, the amplitude-weighted phase interpolation is affected by the nonlinearity of the trigonometric function, introducing large distortion and deteriorating the linearity of the system. Summary of the Invention

[0003] This invention addresses the problems of complex structures in existing technologies leading to additional delays and power consumption in clock circuits. It proposes a charge-injection-based phase rotator that employs a unique charge-injection phase modulation method, possesses intrinsic linearity, and does not introduce static power consumption. It can be applied to phase adjustment in phase-locked loops or clock data recovery circuits or other phase modulation systems. It can perform phase adjustment on multiple output clock signals with frequencies above GHz and supports coverage of the entire cycle. The accuracy of phase adjustment is controlled by an internally integrated control word.

[0004] This invention is achieved through the following technical solution:

[0005] This invention relates to a phase rotator based on charge injection, comprising: a pulse generation circuit and an injection charge generation circuit, a clock phase selection circuit, and a counting control circuit connected thereto. The output of the injection charge generation circuit is connected to an oscillator, and the phase of the oscillator's output clock is controlled by controlling the amount of injected charge, the injection time, and the number of injections. The clock phase selection circuit, based on the multi-phase clock output by the oscillator, uses a control word to select one phase of the clock signal and output it to the pulse generation circuit. The pulse generation circuit is triggered by the clock signal and an enable signal output from the counting control circuit, generating a pulse signal with adjustable pulse width and outputting it to the injection charge generation circuit to inject the injected charge into the oscillator, thereby achieving a single phase shift of the output clock. The counting control circuit, based on the number of pulses generated and an externally input phase control word, controls the opening and closing of the output enable signal to control the number of phase shifts.

[0006] Technical effect

[0007] This invention achieves oscillator output phase change through charge injection, and modulates the phase by repeatedly injecting charge into the oscillator using counting control logic. Compared to existing technologies, this invention enables the output phase to change according to the input control word. The injection circuit stops operating after phase adjustment is complete, thus avoiding the introduction of static power consumption. Furthermore, because phase adjustment is achieved through multiple injections, the behavior of each injection is consistent for the oscillator; therefore, this invention is intrinsically linear and does not cause linearity issues. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the structure of the present invention;

[0009] Figure 2 This is a schematic diagram of the invention;

[0010] Figure 3 This is a technical rendering. Detailed Implementation

[0011] like Figure 1 As shown in the figure, this embodiment relates to a phase rotator based on charge injection, including: a pulse generation circuit and an injection charge generation circuit, a clock phase selection circuit, and a counting control circuit connected thereto. The output of the injection charge generation circuit is connected to an oscillator, and the phase of the oscillator's output clock is controlled by controlling the amount of injected charge, the injection time, and the number of injections. The clock phase selection circuit selects one phase of the clock signal based on the multi-phase clock output by the oscillator using a control word. Output to pulse generation circuit; pulse generation circuit is powered by clock signal. and the enable signal output by the counting control circuit Trigger, generate pulse width An adjustable pulse signal is output to the charge injection generation circuit to generate an injection charge injection oscillator, thereby achieving a phase shift of the output clock; the counting control circuit controls the opening and closing of the output enable signal according to the number of pulses generated and the externally input phase control word to control the number of phase shifts.

[0012] like Figure 1 As shown, the injected charge generation circuit includes: a plurality of adjustable current source arrays connected in parallel, a pulse enable switch, and an injection capacitor. Among them: the pulse enable switch controls the current source to turn on and off according to the pulse signal, thereby generating an injected pulse current, and the injection capacitor... It receives pulsed current and stores charge on the capacitor plates, outputting the injected charge. , The injected current is the output of the current source array. The value of the injected capacitor, i.e., by controlling the amount of injected charge, can adjust the magnitude of the phase shift for each injection. According to the theory of the impulse sensitivity function (ISF), the resulting phase shift is... , For the output phase shift of a single injection, This is the pulse sensitivity function of the oscillator itself.

[0013] The counting control circuit includes a numerical comparator and a counter, wherein the numerical comparator outputs an enable signal based on an externally input phase control word (PCW). The counter records the number of times the enable signal is triggered and compares it with the numerical comparator to control the start and stop of the charge injection, thereby controlling the number of charge injections to adjust the phase of the output clock to the phase corresponding to the target PCW.

[0014] Through specific experiments, after powering the aforementioned phase rotator circuit, the oscillator center frequency was adjusted to 8GHz, and the phase of the test clock output was observed. This was achieved by adjusting the phase control word PCW from 0 to 128 and switching between different pulse widths. and current source output current The change in the output clock phase is measured. The test results are as follows: Figure 3 As shown, the output phase can vary from 0° to 502° to cover the entire cycle, achieving phase adjustability. Furthermore, the perfectly linear phase output curve demonstrates the intrinsic linearity of the phase shift characteristic of this design. This is also demonstrated with different pulse widths. and current source output current The phase modulation accuracy can be varied from 0.72 ps to 1.36 ps.

[0015] like Figure 2 As shown, according to the theory of the pulse sensitivity function (ISF), any charge injected at any time during the oscillator period will cause a shift in the output phase. The figure shows the ISF function of a typical ring oscillator. Based on the time-varying nonlinear relationship between injected charge and phase transition given by this function, the influence of injected charge at different times on the oscillator output phase change can be quantified.

[0016] like Figure 2 As shown below, the clock phase selector controls the selection of phase phases. With a fixed phase relationship The timing of the injection is controlled, thereby controlling the polarity and magnitude of the phase shift generated by the injected charge. This phase shift is maximum when injected at the zero-crossing point and minimum when injected at the peak point. Injection during the clock rise will cause phase lag, while injection during the clock fall will cause phase lead. Furthermore, since the relationship between the injection timing and phase shift is uniquely determined by the ISF function, the impact of the injection behavior on the phase within each cycle is predictable. Once the clock phase selector selects the phase, the correspondence between the injection timing and the phase is determined, thus enabling the signal for each cycle... The phase shift generated by the enable is kept consistent, and phase modulation is achieved by controlling multiple injections, so this phase modulation method has intrinsic linearity.

[0017] Compared to existing technologies, this invention achieves output clock phase shift by generating a charge injection oscillator source and adjusts the output phase by controlling the number of injections. Once the target output phase is reached, the counting control circuit is turned off, thus eliminating dynamic power consumption and improving energy efficiency. Furthermore, since the behavior of each injection is identical, this phase adjustment method exhibits intrinsic linearity, improving linearity performance.

[0018] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A phase rotator based on charge injection, characterized in that, include: The circuit includes a pulse generation circuit and connected to it an injection charge generation circuit, a clock phase selection circuit, and a counting control circuit. The output of the injection charge generation circuit is connected to an oscillator, controlling the phase of the oscillator's output clock by controlling the injection charge amount, injection time, and injection count. The clock phase selection circuit, based on the multi-phase clock output from the oscillator, uses a control word to select one phase of the clock signal and output it to the pulse generation circuit. The pulse generation circuit, triggered by the clock signal and the enable signal output from the counting control circuit, generates an adjustable pulse signal and outputs it to the injection charge generation circuit to inject the injection charge into the oscillator, thereby achieving a single phase shift of the output clock. The counting control circuit, based on the number of pulses generated and the externally input phase control word, controls the opening and closing of the output enable signal to control the number of phase shifts.

2. The phase rotator based on charge injection according to claim 1, characterized in that, The injected charge generation circuit includes: a plurality of parallel adjustable current source arrays, a pulse enable switch, and an injection capacitor. Among them: the pulse enable switch controls the current source to turn on and off according to the pulse signal, thereby generating an injected pulse current, and the injection capacitor... It receives pulsed current and stores charge on the capacitor plates, outputting the injected charge. , The injected current is the output of the current source array. The capacitance value of the injected capacitor, i.e., by controlling the amount of injected charge, can adjust the phase shift magnitude of each injection. According to the theory of pulse sensitivity function (ISF), the resulting phase shift is... , For the output phase shift of a single injection, This is the pulse sensitivity function of the oscillator itself.

3. The charge-injection-based phase rotator according to claim 1, characterized in that, The counting control circuit includes a numerical comparator and a counter, wherein the numerical comparator outputs an enable signal based on an externally input phase control word (PCW). The counter records the number of times the enable signal is triggered and compares it with the numerical comparator to control the start and stop of the charge injection, thereby controlling the number of charge injections to adjust the phase of the output clock to the phase corresponding to the target PCW.

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