Relaxation oscillator with adjustable temperature coefficient

Abstract

The invention discloses a relaxation oscillator with an adjustable temperature coefficient. The relaxation oscillator with the adjustable temperature coefficient comprises a reference voltage generation circuit BGP, a voltage-stabilized power circuit LDO and an oscillator circuit OSC; the reference voltage generation circuit BGP is connected with the voltage-stabilized power circuit LDO; the voltage-stabilized power circuit LDO is connected with the oscillator circuit; the reference voltage generation circuit BGP comprises a voltage comparer A0, a resistor R1 and a transistor V1; the oscillator circuit OSC comprises an amplifier A1, transistors V2-V6, comparers CM1 and CM2, current sources I1-I3, capacitors C1 and C2, and NAND gates U1 and U2. According to the relaxation oscillator with the adjustable temperature coefficient, the temperature coefficient of each chip can be adjusted separately on the original basis, the problems that the proportion of time delay in a frequency becomes bigger and bigger when the relaxation oscillator is applied to high-frequency design and the differences among the temperature coefficients of chips are relatively big as the time delay is affected by the temperature and the technology are solved, and the yield of the chips is accordingly improved.

Description

technical field [0001] The invention relates to a relaxation oscillator, in particular to a relaxation oscillator with adjustable temperature coefficient. Background technique [0002] The oscillator plays a very important role in the MCU, and is often used for system clock timing and so on. Although the crystal oscillator has high frequency stability, that is, a small voltage coefficient and temperature coefficient. But it may increase the number of PADs and peripheral devices, which is inconvenient to integrate. The relaxation oscillation can realize full internal integration, and there are two realization formulas: These two formulas correspond to different solutions respectively. The first is to generate a reference current and a reference voltage, the reference current charges the capacitor, when the capacitor voltage reaches V REF When , this period is half a cycle, because the charging current and reference voltage have a higher temperature coefficient and volt...

AI Technical Summary

Problems solved by technology

Both of these schemes do not consider the delay and the influence of process changes on frequency with temperature. As the frequency becomes higher and higher, the proportion of circuit delay becomes larger and larger, and the working status of the comparator and other circuits in the circuit will be affected. Affected by voltage, temperature and process, thus affecting the accuracy of the frequency

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