RC (resistance-capacitance) oscillator

Abstract

The invention discloses an RC (resistance-capacitance) oscillator, which comprises a bias voltage generating circuit, a charging and discharging current generating circuit, a charging and discharging circuit, an external hysteresis voltage generating and gating circuit, an internal hysteresis comparator and a feedback control signal generating circuit. By adopting the internal and external hysteresis comparator, the reference current and the reference voltage can change along with changes in the voltage of an external power supply, so that effects of the voltage of the power supply on the output frequency can be overcome. Meanwhile, since resistors with different temperature coefficients are adopted, the reference current cannot be affected by the temperature. Moreover, since only one comparator is adopted in the overall structure, effects of the temperature, caused by the input offset voltage in double comparators, on the output frequency can be overcome.

Description

technical field [0001] The invention belongs to the technical field of integrated circuits, and in particular relates to an RC oscillator with high precision and adjustable frequency with internal and external hysteresis comparators. Background technique [0002] Generally, the RC oscillator generates the oscillation frequency by delaying the charge and discharge of the resistor and capacitor. The generated frequency is easily affected by the power supply voltage and temperature. In order to overcome the influence of the power supply voltage and temperature on the output frequency of the RC oscillator, many designed and invented high precision RC oscillators such as figure 1 As shown, it is the structure diagram of the current high-precision RC oscillator with dual comparators, which consists of charge and discharge capacitor C0, comparators A1 and A2, RS flip-flop, reference voltage source generation circuit, charge and discharge current generation circuit and charge and di...

AI Technical Summary

Problems solved by technology

[0003] The above oscillator reduces the dependence of the reference current and reference voltage on the power supply voltage and temperature, thereby reducing the influence of the power supply voltage and temperature on the output frequency; in addition, for some specific applications, it is necessary to adjust the output frequency to adapt to certain specific conditions of the circuit. Function, while R and C in the above oscillator are integrated on the chip, the frequency adjustment is difficult, and the application range is narrow; at the same time, the double comparator structure is adopted, which reduces the influence of the power supply voltage on the output frequency, and also brings new features to the circuit. The problem is that the input offset voltages of the dual comparators are not the same, and the input offset voltages of the dual comparators are V OS1 and V OS2 , the difference between the two | V OS1 -V OS2 |Up to mV level, and they are all temperature-sensitive quantities, so the output frequency is still affected by temperature

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