Relaxation oscillator improving linearity of control current-output frequency significantly

Abstract

A relaxation oscillator improving the linearity of control current-output frequency significantly comprises an oscillating circuit, a delay error detection circuit and a modulating current generation circuit. The delay error detection circuit is used for detecting the peak voltage of charge-discharge capacitors in the oscillating circuit, generates delay error erasure signals according to the peak voltage and enables the oscillator to oscillate at preset frequency. The modulating current generation circuit generates a corresponding additional control current according to the peak voltage of the charge-discharge capacitors, increases the charge rate of the charge-discharge capacitors, eliminates delay influence from the oscillating circuit and improves the linearity of control current-output frequency. Due to the fact that the additional control current output by the modulating current generation circuit enables voltage of the charge-discharge capacitors C1 and C2 to be increased, jittering of the signals output by the relaxation oscillator can be reduced.

Description

technical field [0001] The invention relates to a relaxation oscillator, in particular to a relaxation oscillator which significantly improves the linearity of control current-output frequency, and belongs to the technical field of CMOS integrated circuits. Background technique [0002] In large-scale integrated circuits, clock signals are generally generated by oscillators. The relaxation oscillator has a simple structure, low cost, easy integration, and relatively low power consumption. It is the most widely used clock generation circuit in the oscillator. [0003] In the application of signal modulation and demodulation, data recovery of storage system, etc., the control current-frequency of the relaxation oscillator used is required to have a high linearity, so as to reduce distortion and increase the relaxation oscillation frequency range of the device. In the relaxation oscillator, the linearity of the control current-frequency is related to the delay of the control ...

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Problems solved by technology

[0028] Although, a current-controlled relaxation oscillator with dual timing capacitors will delay by 4t in one cycle d reduced to 2t d , but the output frequency of the oscillator is still subject to the control circuit of the timing capacitor oscillation amplitude and the delay 2t of the PMOS transistor MP1, NMOS transistor MN1, PMOS transistor MP2, and NMOS transistor MN2 as control switches d effect, especially at high frequencies, the 2t d The delay is even greater than the period of the oscillator output waveform, which not only reduces the linearity of the frequency-controlled current, but also limits the maximum frequency range of the oscillator. Therefore, it is necessary to further improve the current-controlled relaxation oscillator with dual timing capacitors. , to reduce the effect of delay

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