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设计了一种用于AC-DC电源芯片的低温漂、高精度、可降频振荡器。该电路利用系统中的LDO模块产生的基准电压,在MOS和BJT两种不同类型的跟随器上产生两路正负温度系数的电流。对电流进行正负温度补偿后,在逻辑控制下对电容充放电,经过双门限比较器和整形电路产生100kHz的方波信号。该电路具备在系统启动中具有重要作用的自启动功能。采用0.5μm BiCMOS工艺,利用Hspice和Cadence进行仿真,在芯片系统典型应用环境下,仿真得到振荡频率为100.2kHz,当温度在-40℃~125℃之间变化时,振荡器的频率随温度的偏移在1%以内。该振荡器已被成功应用于一款AC-DC电源管理芯片的设计中。
A low-temperature drift, high-precision, frequency-reducible oscillator for AC-DC power chips is designed. The circuit uses the reference voltage generated by the LDO module in the system to generate two positive and negative temperature coefficient currents on two different types of followers, MOS and BJT. After the current is compensated for positive and negative temperature, the capacitor is charged and discharged under logic control, and a square-wave signal of 100 kHz is generated by the double-threshold comparator and the shaping circuit. This circuit has a self-starting function that plays an important role in system startup. The 0.5μm BiCMOS process is used to simulate with Hspice and Cadence. Under the typical application of the chip system, the oscillation frequency is 100.2kHz. When the temperature varies from -40 ℃ to 125 ℃, the frequency of the oscillator varies with the temperature Offset within 1%. The oscillator has been successfully used in the design of an AC-DC power management chip.