How to connect photodiode to fully differential opamp ?

[leon30]

Hello,

I'm currently researching custom made photodiode and its possibilities for signal processing with the regard of an application as an integrated rpm detector (IC). How to connect the photodiode to the input of a fully differential CMOS OPAMP ?
Because this will be an integrated circuit I'm thinking to process the signal with opamp with some sort of offset cancellation technique with switched capacitors, so what type of opamp do you think will be suitable - voltage amplifier like folded-cascode or current feedback amplifier architecture ?

Thank you for your reply,
Best regards

 

[TXBDan]

I'm not exactly sure if this is what you're after, but I was just reading an MCP601/2/3/4 datasheet and it has an application schematic for a photodiode. Section 4.8.3:
https://ww1.microchip.com/downloads/en/DeviceDoc/21314g.pdf

 

[leon30]

Unfortunately this is single ended operation - 2 inputs, one of which is grounded and 1 output. I'm searching for a fully differential - 2 inputs to 2 outputs from the opamp where the effective signal swing is Vn = -(Vp) so Vout = Vp - Vn = Vp - (-Vp) = 2Vp.

 

[FvM]

If you rely on the fully differential toplogy, why don''t you connect the photodiode differentially in photovoltaic mode? It's easy.

 

[leon30]

You mean photovoltaic mode like in here: https://www.aptechnologies.co.uk/support/photodiodes/photodiode-theory-of-operation where the diode is directly connected to both opamp inputs or in zero bias like in this thread: https://www.edaboard.com/threads/154202/#post659132 ? I see as a main benefit the lower power consumption, because lack of high reverse voltage bias when the photodiode is in photoconductive mode like here: **broken link removed**, here: **broken link removed** and the ones with a common ground point: **broken link removed** (page 14, figure 1-28 absorptiometer). Which one of these topologies is the best one for a simple on-off high intensity light detection with frequency of less than 1kHz, in the case of diode capacitance in the range of couple of nF?