A Micropower Voltage, Current, and Temperature Reference for a Low-Power Capacitive Sensor Interface

In this paper, a micropower CMOS voltage, current, and temperature reference fabricated in a 0.13mum CMOS process is presented. This bandgap-based circuit provides all reference voltages and currents, and temperature information for a low-power interface of a three-axis capacitive microaccelerometer. The total measured current consumption including all required reference voltage buffers, current mirrors, and scaling circuitry is 23.1 muA. The simulated current consumption of the core circuit is 5.5 muA. According to system measurements, the required resolutions, 10 bits for the reference voltages and 9 bits for the temperature reference, are achieved. The measured TC for the voltage reference is 9.9ppm/degC, and the analog output of the temperature reference is linear with a 4.9 mV/degC slope.