Steve Zissou
New Member
HI. Im designing a temperature sensor circuit to measure the heated effect of a silicon photo diode. For the temperature sensors i've used two thermistors, attaching one of them to the backside of a silicon photo diode and the other as a reference sensor on a piece of copper. By illuminating the diode with a laser, the change in resistance in the thermistor will provide a voltage drop different from the reference thermistor. To amplify the difference i've used an instrumentation amplifier (AD620) wtih a gain about 225. But im having noise issues. Any idea where it origins from? The circuit is inside an aluminium box. And input voltage is 5V.
Thanks
Thanks