Multi-band two-stage ring voltage-controlled oscillator for phase-locked loop

Abstract

The invention relates to a multi-band two-stage ring voltage-controlled oscillator for a phase-locked loop, and belongs to the field of integrated circuit designing. The ring oscillator is formed by two stages of delay units, delay is prolonged by means of an additional latch to keep oscillation, and the oscillation frequency is controlled by a tail current source. Compared with a general structure, the ring oscillator has the advantages that by additionally adding a switch, 2<n>-1 frequency bands are increased (n represents the switch stage number); the increased frequency bands can better adapt to changes of the process bias, a power supply and the temperature, and therefore the phase-locked ring can be always locked to the needed frequency point; and switch control signals can be provided by an additional digital circuit (such as an automatic frequency calibration circuit).

Description

technical field [0001] The invention belongs to the technical field of integrated circuit design, in particular to a multi-band two-stage ring voltage-controlled oscillator used in a phase-locked loop. Background technique [0002] Ring voltage-controlled oscillators (Ring Voltage-controlled Oscillators, Ring VCOs) can save a lot of chip area compared with inductor-capacitor oscillators, so as to realize low-cost oscillators, so they are widely used in integrated circuits. [0003] figure 1 Is the schematic diagram of the two-stage ring voltage controlled oscillator, figure 2 Its transistor level circuit diagram. The general two-stage oscillator cannot oscillate. Here, by adding a set of latches and introducing additional delay time, the oscillation of the two-stage ring oscillator can be realized. The advantage of reducing the number of stages is to save power consumption and area, and at the same time reduce phase noise. The VCO is in the current hungry mode, and the ...

AI Technical Summary

Problems solved by technology

The output frequency of the Ring-VCO will vary significantly with the process, power supply voltage, temperature (PVT), etc. Therefore, the frequency deviation of the Ring-VCO with a single frequency band may cause the phase-locked loop to fail to lock

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