selection of best transimpedence amplifier

Hi Veerabau,

the OPA857 is often used for LIDAR applications.

TI has some LIDAR reference designs. Make a search.

Kai

Hello Veerababu, 

If you work through the numbers that is a 500kohm total gain at say 100MHz!! not likely in one stage, might consider the OPA857 or OPA855 at a low enough transimpedance first stage gain to get the BW followed by something like the THS4541 FDA or LMH6554 FDA

Hi Kai,
Many thanks for the reply. Can you please let me know what parameters are needed to look for, in a transimpedance amp ?
Is there a good app note you can recommend ?

thanks,
veerababu

Hi Veerababu,

a critical parameter is the detector capacitance. The higher the more difficult to get the TIA working stably. Make yourself familiar with TINA-TI and run a simulation of your intended circuit. And when doing the layout of PCB make the connections arround the -input of OPAmp as short as possible. Every millimeter counts!

Kai

Dear Kai,

Thank you very much for the information !

I have a board with the APD connected to a AD8015  transimpedance amp. When there is no laser light falling on the APD, I measured the differential output with a differential probe. The output on the oscilloscope was noise with a peak to peak value of about 2mV.

My APD provides a current of 20 nA to 1 uA when laser light falls on it. The AD8015 has a transimpedance of 20 Kohms. So the output comes to max.20mV and min.400 microvolts. The problem is when the min. voltage is output by the amp. Would it be better to have a current amplifier connected between the APD and the transimpedance amp ?

Thanks,

Veerababu