hanua
Newbie level 3
Hi guys,
New to the forum and it seems I have some question regarding using an op-amp to present a real word input to a differential ADC.
I'll present some information of the time of input I want to be sampling. The input comes from a detector which has negative going pulses with rise times from 20-40 nsec, falling times around 100 nsec. Pulse amplitudes are from -20 mV to -100 mV. Basically what I want to do, is to use the op-amp to AC couple the detector input to the ADC and have the pulses taking up the whole range of the ADC.
The ADCs I'm using will be the ADS62P28/29/48/49. All of these are interchangeable as long as I have the proper connections made on the board. Output from the ADC will be to a FMC connector on a FPGA board.
The part I'm not really confided is the configuration of the op-amp to ADC since i've never worked with this before.
I'll post some schematics of what I have so far.
This first one is the input from the BNC connector to the op-amp. Right now, I have it configured for a differential gain of 1.
I understand that I basically need to take the input signal range, amplify it and shift it into the input range of the ADC. Which I believe is the job of the op-amp. I've seen so many configurations of op-amps which seem to do the same thing that I'm just confused now.
This is the ADC configuration.
The ADC input range seems to be 2Vpp. What does this mean? Is this between +1 V to -1V for what does it mean? Also what is the purpose of the Vcm and how does it need to be connected between the op-amp and ADC.
New to the forum and it seems I have some question regarding using an op-amp to present a real word input to a differential ADC.
I'll present some information of the time of input I want to be sampling. The input comes from a detector which has negative going pulses with rise times from 20-40 nsec, falling times around 100 nsec. Pulse amplitudes are from -20 mV to -100 mV. Basically what I want to do, is to use the op-amp to AC couple the detector input to the ADC and have the pulses taking up the whole range of the ADC.
The ADCs I'm using will be the ADS62P28/29/48/49. All of these are interchangeable as long as I have the proper connections made on the board. Output from the ADC will be to a FMC connector on a FPGA board.
The part I'm not really confided is the configuration of the op-amp to ADC since i've never worked with this before.
I'll post some schematics of what I have so far.
This first one is the input from the BNC connector to the op-amp. Right now, I have it configured for a differential gain of 1.
I understand that I basically need to take the input signal range, amplify it and shift it into the input range of the ADC. Which I believe is the job of the op-amp. I've seen so many configurations of op-amps which seem to do the same thing that I'm just confused now.
This is the ADC configuration.
The ADC input range seems to be 2Vpp. What does this mean? Is this between +1 V to -1V for what does it mean? Also what is the purpose of the Vcm and how does it need to be connected between the op-amp and ADC.