Integrated 1.2 /spl mu/m CMOS photodiodes, transimpedance amplifier, 12 bits A/D converter, and DSP interface for microinstrument applications

摘要

Integrated CMOS photodiodes, transimpedance amplifier and dual-slope ADC are designed and fabricated in 1.2 /spl mu/m AMI ABN MOSIS process. The quantum efficiency of n-diffusion p-base junction photodiode with size 200 /spl mu/m/spl times/200 /spl mu/m is 21.7%. The transimpedance amplifier uses T-feedback to realize large equivalent feedback resistance. The 12-bit dual-slope A/D converter with size 450 /spl mu/m/spl times/950 /spl mu/m, an integrating resistor of 273 K, and an external capacitor of 1.5 nF has conversion time from 0.41 ms to 0.81 ms when fclock=10 MHz. The offset error is 5 LSB and the integral nonlinearity error is 0.4% of full scale. The chip derived from this project is successfully used in a novel microinstrument for heart rate and breathing rate monitor.