Current-to-Voltage Converter Using Current-Mode Multiple Reset and its Application to Photometric Sensors

Abstract

Using a current-mode multiple reset, a current-to-voltage(I-V) converter with a wide dynamic range was produced. The converter consists of a trans-impedance amplifier(TIA), an analog-to-digital converter(ADC), and an N-bit counter. The digital output of the I-V converter is composed of higher N bits and lower bits, obtained from the N-bit counter and the ADC, respectively. For an input current that has departed from the linear region of the TIA, the counter increases its digital output, this determines a reset current which is subtracted from the input current of the I-V converter. This current-mode reset is repeated until the input current of the TIA lies in the linear region. This I-V converter is realized using 0.35 LSI technology. It is shown that the proposed I-V converter can increase the maximum input current by a factor of 2 N and widen the dynamic range by 6 N . Additionally, the I-V converter is successfully applied to a photometric sensor.