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四、固体基准源在单片D/A转换器设计中,稳定基准的设计最为关键。稳定基准源的主要指标是热稳定性。 (一)齐纳二极管基准源齐纳二极管基准源是电子系统应用较早且较广的一种固体基准源。产生基准电压的方法不外乎图11所示的四种。即(a)利用齐纳二极管在适当偏置电流下的零温度系数击穿点产生基准电压。(b)利用齐纳管端电压的正温度系数和正偏,二极管端电压的负温度系数串联补偿的原理产生基准电压。(c)利用建立电阻比来获得基准电压。(d)利用平衡电桥产生基准电压。电路计算表明(c)的输出基准为:
Fourth, the solid reference source In the monolithic D / A converter design, the design of the most stable base of the key. The main indicator of a stable reference source is thermal stability. (A) Zener diode reference source Zener diode reference source is an earlier and wider application of electronic systems as a solid reference source. The method of generating a reference voltage is nothing more than the four shown in FIG. 11. That is, (a) a Zener diode is used to generate a reference voltage at a zero temperature coefficient breakdown point at a suitable bias current. (b) Using the positive temperature coefficient of zener terminal voltage and the principle of series compensation of positive temperature and negative temperature coefficient of diode terminal voltage, a reference voltage is generated. (c) Use the resistor ratio to get the reference voltage. (d) Use a balanced bridge to generate the reference voltage. Circuit calculations show that the output of (c) is: