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 0.13
μ
m 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
μ
A. The simulated current consumption of the core circuit is 5.5
μ
A. 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/°C, and the analog output of the temperature reference is linear with a 4.9mV/°C slope.