Fully differential frequency and phase detector with adjustable reset delay

Abstract

The invention discloses a fully differential reset delay adjustable frequency and phase discriminator, which comprises four RS triggers, nand gates G0, a delay control circuit DL and two output buffer circuits, wherein all the four RS triggers have the structures that two nand gates are crossed and coupled; all nand gates are fully differential static CMOS (Complementary Metal Oxide Semiconductor) logics with positive feedback; the DL delay circuit is formed by cascading three delay fixed units and three delay controllable units; and each buffer circuit is formed by cascading fully differential phase inverters with transistors of multiplied sizes and positive feedback. Reset signals generated by the nand gates G0 are delayed by the DL circuit to perform reset control on the four RS triggers; and four paths of pulse control signals are output by the second RS trigger and the fourth RS trigger through the buffer circuits which are connected with the second RS trigger and the fourth RS trigger respectively. The discriminator has the advantages of small phase discrimination error, controllable reset delay, high driving capacity and high matching degree output of the four paths of pulse control signals and can be used for a high-performance phase locked frequency synthesizer.

Description

technical field [0001] The invention belongs to the technical field of integrated circuit design and relates to a phase-locked frequency synthesizer circuit, in particular to a frequency and phase detector with an adjustable reset delay of a fully differential structure, which can be used in a frequency synthesizer of a radio frequency front-end receiver system. Background technique [0002] At present, the phase-locked frequency synthesizer is widely used in the fields of electronic communication and radio frequency technology, and has become an indispensable basic module in various electronic equipment and communication equipment. Such as figure 1 As shown, the phase-locked frequency synthesizer is composed of a frequency detector, a charge pump, a loop filter, a voltage-controlled oscillator and a frequency divider. The frequency and phase detector compares the frequency and phase of the input reference signal and the output signal of the frequency divider, and generates...

AI Technical Summary

Problems solved by technology

[0011] To sum up, common frequency and phase detectors have the following disadvantages: the phase detection error is too large, the reset delay time is uncontrollable, the driving ability of the charge pump is insufficient, and the four output pulse control signals do not match.

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