Low power ASIC for high temperature applications

This paper describes the design and implementation of a low power/low voltage mixed signal BiCMOS ASIC that operates at temperatures up to 200°C. The ASIC is integrated into a gauge for downhole pressure and temperature measurements. It incorporates four measurement channels (CLK1-clock one, CLK2-clock two, P-pressure, T-temperature), with four high precision X-tal Pierce oscillators and a signal processing path for each channel. The output frequency from the CLK1 channel is used as a precision reference for the pressure and temperature channels and as an external clock. The ASIC is designed for high pressure transducers and incorporated into a downhole memory and wireline quartz gauge. The ASIC was fabricated into a 1.2 μm BiCMOS double poly, double metal process. The voltage supply range is from 5 V to 3.3 V and the circuit occupies a silicon area of 15 mm². The ASIC is packaged in a ceramic 28 pin SOIC package