Linear phase error comparator applied to phase-locked loop of image sensor

Abstract

The invention relates to the technical field of analog integrated circuits, and provides a linear phase error comparator applied to a phase-locked loop of an image sensor, which comprises a ramp generator and a control signal generation circuit. The control signal generation circuit is used for sampling and comparing an input reference clock signal and an output clock signal, generating a control signal containing phase difference information and controlling charge and discharge of the ramp generator; the ramp generator comprises a reference current source, a voltage follower, a first capacitor, a reference voltage source, a first PMOS transistor, a second PMOS transistor, a third PMOS transistor, a fourth PMOS transistor, a fifth PMOS transistor, a sixth PMOS transistor, a seventh PMOS transistor, an eighth PMOS transistor, a ninth PMOS transistor, a first NMOS transistor and a second NMOS transistor. Linear and continuous phase error comparison can be realized, the quantization noise of the phase error comparator is reduced, and a low-noise phase-locked loop is realized.

Description

technical field [0001] The invention relates to the technical field of analog integrated circuits, in particular to a linear phase error comparator applied to a phase-locked loop of an image sensor. Background technique [0002] In recent years, CMOS image sensors have been widely used in people's lives due to their high integration and low cost. Phase-locked loop (PLL, Phase Lock Loop) is an important part of the CMOS image sensor, it provides the basic clock signal to the analog-to-digital converter, interface circuit and other modules in the image sensor, it is crucial to the performance of the CMOS image sensor influences. [0003] In the CMOS image sensor, according to the type of the phase-locked loop, it can be divided into an analog charge pump phase-locked loop (CPPLL) and an all-digital phase-locked loop (ADPLL). Among them, the analog charge pump phase-locked loop has good phase noise performance, but the design complexity and power consumption are higher than t...

AI Technical Summary

Problems solved by technology

[0006] The invention mainly solves the technical problem that quantization noise is difficult to eliminate in traditional fractional phase errors, and proposes a linear phase error comparator applied to image sensor phase-locked loops, which can be used in large-scale image sensor all-digital phase-locked loops, and has low Noise, low power consumption characteristics

Images