Resistance-capacitance type ring oscillator

Abstract

The present invention discloses a resistor-capacitor type ring oscillator, including two current paths and two gained phase modulation branches. The first current path including an NMOS transistor M1and a PMOS transistor M2, the second current path consist of a PMOS transistor M3 and a current source Iss in tandem connection, the first gained phase modulation branch includes a capacitor C1, a resistor R1, a PMOS transistor M5 and a PMOS transistor M6, the second gained phase modulation branch consist of a fourth PMOS transistor and a fourth NMOS transistor in tandem connection. The present invention is characterized in that the transfer function of a first loop generates a low frequency left half-plane zero point at the first gained phase modulation branch and couples with a right half-plane zero point at the second current path through the second modulation branch, thereby satisfying the Barkhausen rule and achieving an oscillation. The oscillator has a simple structure, a low implementation cost and generates the oscillation with the frequency of 1.544 M in the working range of 2.7 to 5V with the stability as high as 407 ppm.

Description

technical field [0001] The invention belongs to the analog integrated circuit technology, and in particular relates to a resistance-capacitance (RC) ring oscillator, which can provide a highly stable oscillation frequency within a wide operating voltage range. Background technique [0002] Oscillators are widely used in integrated circuits and are an integral part of many electronic systems, from clocking microprocessors to carrier synthesis in cellular phones, and are an integral part of phase-locked loops (PLLs). . Because of its large footprint, the application of LC oscillators in some microcircuits is greatly limited, so the design of RC oscillators with relatively small areas and high stability, especially wide operating voltage ranges , has become a hot spot in analog integrated circuits. [0003] Because the oscillation frequency is closely related to the tail current source, we consider an ideal current source in the circuit. In fact, only a weak correlation betwe...

AI Technical Summary

Problems solved by technology

A general RC ring oscillator is composed of multiple stages of the same circuit. For example, a commonly used single-ended ring oscillator has three stages, five stages, and a double-ended ring oscillator can be three, four, and five stages, because each stage can generate a maximum of 90° Phase translation, for a three-stage ring oscillator, each stage produces a phase shift of 60°, and only the total gain is sufficient to generate oscillation, but in order to stabilize the oscillation frequency of this general ring oscillator, it often requires Requires a more complex circuit

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