A CMOS Interface for a Gas-Sensor Array with a 0.5%-Linearity over 500k/spl Omega/-to-1G/spl Omega/ Range and 2.5/spl deg/C Temperature Control Accuracy

The interface IC includes 8 read-out channels and 2 closed-loop temperature control circuits, is fabricated in 0.35μm 2P4M CMOS and dissipates 27mW from a 3.3V supply. The read-out structure, based on a controlled oscillator, achieves a 0.5% linearity and a SNR >48dB over the 500kΩ-1GΩ sensor resistance range with a 114dB DR. The temperature control systems maintain a 100°C gradient in the range 100 to 400°C with ±2.5°C accuracy