RC (Resistance Capacitance) relaxation oscillator of comparator offset

Abstract

The invention discloses an RC relaxation oscillator of a comparator offset, and is used for solving the technical problems that the stabilities of the frequency and the duty ratio of the prior RC relaxation oscillator are bad. The RC relaxation oscillator provided by the technical scheme comprises a reference voltage generating circuit, a capacitor charging-discharging circuit, a comparator and an inverter chain. A charge pump is used to generating two periodic triangular wave signals, the phase difference of which is 180 degrees; and, the comparator compares two triangular wave signals to generate a clock signal. Since the peak-to-peak value of the triangular wave signals is determined by a fixed reference voltage and is irrelevant to the offset voltage of the comparator, the charging or discharging time of the capacitor remains unchanged at each working state, so that the frequency of the oscillator is not changed. Due to the comparator offset, the frequency and the duty ratio of the oscillator are not affected by the offset voltage of the comparator; and, the stabilities of the frequency and the duty ratio are good. And moreover, only one comparator is used, so that the amount of the comparators is reduced by half.

Description

Technical field [0001] The invention relates to an RC relaxation oscillator, in particular to an RC relaxation oscillator with a comparator offset cancellation. Background technique [0002] Clock circuits or timers are key modules of low-power electronic devices. For example, in a wireless sensor network, the clock circuit is used as a timer to periodically wake up nodes to send and receive signals. Its power consumption, integration level, and frequency stability are all critical. The RC relaxation oscillator has the characteristics of low power consumption and easy on-chip integration, which is very suitable for application in these electronic devices. In practice, the frequency of the oscillator is affected by factors such as temperature, voltage, and technology. It is of great significance to design a low-power oscillator with a stable operating frequency. [0003] Reference Figure 7 . The document "SLJGierkink and E.van Tuij, A coupled sawtoothoscillator combining low jitt...

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Problems solved by technology

[0004] In order to overcome the disadvantages of poor frequency and duty cycle stability of existing RC relaxation oscillators, the present invention provides an RC relaxation oscillator with comparator offset offset

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