Temperature compensated logarithmic CMOS image sensor using CMOS voltage reference Bandgap method

In this paper, we present a temperature compensation method dedicated to a CMOS logarithmic image sensor with doubled output voltage swing. In this method, we use the principle of CMOS Bandgap Voltage Reference technique. This proposed temperature compensation method is adapted for all photocurrent values. As Bandgap Voltage Reference technique, the compensation circuit generates V_PTAT1 and V_PTAT2 voltages to compensate temperature variation of the sensor output signal voltage (Out-AC-Signal) which we call V_CTAT1 and output reference voltage (V_Ref-ph) which we call V_CTAT2. With this method, a good temperature stability of the sensor response in the temperature range from -30 to 125° C is obtained without changing the sensor operation. In addition, we preserve all the same sensor response characteristics. This approach has been verified via Cadence simulation in a 0.35 μm CMOS technology. This method and the complete circuit are presented in detail with the associated results.