The circuit for increasing output voltage composed of precision logarithmic and logarithmic ratio amplifier LOG102

As shown in the figure, the circuit of increasing output voltage technology composed of LOG102 is shown. In many optical sensor detection applications, increasing output voltage technology is as important as increasing photodiode current function. The circuit in the figure uses a large reference voltage source to generate reference current, which reduces the error caused by LOG102 input offset voltage to a minimum. Reference current IREF flows into I1, and photodiode current IPHOTO flows into I2. When designing, IREF is greater than IPHOTO to meet the requirement. The role of internal amplifier A3 is to generate a level shift of inverting gain, which is used to calibrate the input photodiode current and the corresponding input A/D converter range.