Phase-locked loop

Abstract

The invention discloses a phase-locked loop. The phase-locked loop comprises a phase/frequency detector, a charge pump, a loop filter, a voltage-controlled oscillator, bonding-wire inductor, a buffer, a prescaler and a digital frequency divider, wherein the input end of the phase/frequency detector is connected with the output end of the digital frequency divider and a reference clock; the input end of the charge pump is connected with the output end of the phase/frequency detector; the input end of the loop filter is connected with the output end of the charge pump; the voltage-controlled oscillator uses a resistor as an electro-static discharge guard; the control voltage input end of the voltage-controlled oscillator is connected with the output end of the loop filter; the bonding-wire inductor is connected with the differential output end of the voltage-controlled oscillator; the differential input end of the buffer is connected to the differential output end of the voltage-controlled oscillator; the prescaler is controlled by Gray codes; the differential signal input end of the prescaler is connected with the differential output end of the buffer; the control signal input end of the prescaler is connected with a first output end of a control logic; a signal input end of the digital frequency divider is connected with an output end of the prescaler; and a control input end of the digital frequency divider is connected with a second output end of the control logic. The phase-locked loop provided by the invention has the advantages of high frequency precision and low noise.

Description

a phase-locked loop technical field The invention relates to the technical field of phase-locked loops, in particular to a phase-locked loop with a prescaler controlled by Gray codes and a voltage-controlled oscillator with resistance as ESD. Background technique In a radio frequency transceiver, the phase-locked loop is often the core of the entire system. In the transmitter, the phase-locked loop is used in the frequency synthesizer to generate the transmitted signal or up-convert the transmitted signal. The frequency accuracy and phase noise of the phase-locked loop directly determine the error vector magnitude of the transmitted signal; in the receiver, the phase-locked loop It is often used to generate down-converted local oscillator signals. The frequency accuracy of the phase-locked loop affects the demodulation bit error rate, and the phase noise of the phase-locked loop directly determines the adjacent-order channel selectivity of the receiver. Regarding the pre...

AI Technical Summary

Problems solved by technology

However, the bonding wire inductance is not accurate, which will cause the deviation of the resonance frequency of the voltage-controlled oscillator. The traditional method is to correct the resonance frequency by controlling the capacitor array in the voltage-controlled oscillator.

However, the output of the voltage-controlled oscillator is directly connected to the outside of the chip through the bonding wire, which requires ESD (Electro-Static discharge) protection. The traditional method is to use a diode with a large area, but it has a very large parasitic capacitance, which will make the Severely reduced range for frequency correction

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