Research And Design Of Low Voltage And Power CMOS Oscillator

The 21 st century is called the information age.The information and communication technology revolution has been in the ascendant since the last century.The radio technology and information technology based on electronic technology have gradually matured.The progress of the electronics industry has brought about tremendous changes in human lifestyle.The new generation of communication technology requires a larger bandwidth baseband chip and the processing of more data in the era of big data requires faster computing power,which puts new demands on the development of integrated circuits.As an important module generated by the clock source signal in electronic equipment,high-precision oscillator with low voltage and power consumption has been one of the research focuses of scholars at home and abroad.This paper studies the effects of how the process,power supply voltage and temperature fluctuations affect the output frequency of oscillator and proposes ways to improve the accuracy of the output clock.Two low-power relaxation oscillators of different structures are proposed,which generate a target frequency of 32.768 kHz in the temperature range of-40-80?.The two oscillators,output clocks have smaller temperature drift and power supply linearity.The performance of the oscillator is as follows:(1)The relaxation oscillator based on the inverter scheme proposes a full MOS transistor PTAT current source,which uses a multi-stage inverters and an RC delay unit to form a feedback loop as the oscillator core circuit,which is oscillated by adding a local voltage adjustment circuit.The local voltage adjustment circuit supplies voltage to the oscillator core circuit to isolate the power supply voltage from the oscillator core circuit,reducing the effect of supply voltage fluctuation to the oscillator output frequency.In addition,the threshold voltage temperature characteristic of the MOS transistor in the bias circuit is used to reduce the temperature fluctuation of the inverter delay time.Compensation reduces the temperature drift characteristics of the oscillator.At room temperature,the oscillator output frequency is 33.769 kHz,the relative frequency variation is between-0.049%and 0.353%,and the relative frequency variation is ±0.62‰ in the temperature rangeof-40-40?;(2)The relaxation oscillator based on the comparator scheme uses a 14 nA low-power PTAT current source to provide bias.To improve the accuracy of the clock signal,the resistors in the core circuit are trimed,and the positive and negative temperature coefficient resistors are matched to reduce the temperature drift.At the same time,MOM capacitors with a small temperature coefficient are used.To improve the oscillator output waveform,the comparator output stage is followed by a digital logic unit that shapes and divides the oscillator waveform to produce the desired target frequency.At room temperature,the PTAT bias current source outputs14 nA.The oscillator can consume about 130 nW at 1V supply voltage,producing a stable 32.768 kHz clock signal with a temperature drift of 0.14%/°C in the range of-40-80°C.The frequency is stable in the voltage range of 0.9-1.5V.Through simulation verification,the oscillators of the two structures can produce the expected results and achieve high-precision output frequency while ensuring lower power consumption.