I asking advice on the following issue.
I need to design a photodiode amplifier with the following characteristics:
- photovoltaic mode
- AC signal with with few kHz
- very low noise
- high gain required
- photodiode properies: capacitace ~ 2000 pF , Rs=3000 MOhm
- amplifier output to be fed to ADA2200 Synchronous Demodulator -> AD779x ADC
- eventually DC servo to compensate offset due to ambient light
As this thread points out the opamp input bias current for AC applications only results in a DC offset.
- Is my interpretation correct that as long as the induced offset is not too large I can choose a low voltage noise opamp with an appropriate bandwith ?
- Is there a better way to deal with the DC component of the signal ( due to ambient light ) than using a DC servo circuit as it might introduce a lot of noise ?
- What opamps would be suitable for this kind of application ?
Any advice is highly appreciated!