Delay unit circuit with rail-to-rail voltage linear regulating range and bandwidth-expanding capability

Abstract

The invention discloses a delay unit circuit with a rail-to-rail voltage linear regulating range and bandwidth-expanding capability applied to a high-speed voltage-controlled oscillator (VCO). By simultaneously controlling PMOS and NMOS tubes, the delay unit realizes that control voltage can linearly regulate the frequency of the VCO in a rail-to-rail voltage range, thereby increasing the linear regulating range of the VCO, improving the reliability of the VCO and needing no start-up circuit. By adopting positive feedback in the unit and a technique of accelerating in a VCO ring, the delay unit circuit improves the frequency of the VCO, and also increases the frequency range of the VCO.

Description

technical field [0001] The invention mainly relates to the field of voltage-controlled oscillators in phase-locked loops and clock data recovery circuits, in particular to a differential delay unit circuit applied to high-speed voltage-controlled oscillators. Background technique [0002] A voltage-controlled oscillator (Voltage-Controlled-Oscillator, VCO) is one of the key modules in the phase-locked loop and clock data recovery circuit. In integrated circuits, the most commonly used oscillator structures are RC ring oscillators and LC tuned oscillators. The jitter performance of the LC tuned oscillator is very good, but due to the difficulty of integrating the inductor on the chip, it needs the support of the process; and the ring oscillator is widely used in frequency synthesizers, clock generators and data clocks because of its simple structure and easy integration. recovery circuit. [0003] The structure of the ring oscillator is also divided into single-ended and di...

AI Technical Summary

Problems solved by technology

And as Figure 5 The delay unit shown uses MOS tubes M3 and M4 as load tubes. On the one hand, the sensitivity to the control voltage is too high; on the other hand, its I-V characteristic curve cannot meet the requirements.

Due to the inherent nonlinear effect of MOS tubes, making Figure 4 The I-V curve of the oscillation unit with the structure shown also shows nonlinear characteristics. We always hope that the current can change linearly with the change of voltage, so that the frequency also changes linearly with the change of voltage, but the volt-ampere characteristic curve of a single MOS tube Not linear over a wide range

Then, the linearity of the oscillator formed by connecting the structural stages must be very poor.

In addition, the control tube of the traditional oscillator is either a PMOS tube or an NMOS tube, which inevitably leads to the inability to adjust the frequency of the ring vibration by controlling its control voltage within a certain range, which is for low power supply voltage chip design. , is a disadvantage that cannot be ignored

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