OPA855DSGEVM: OPA855EVM doesn't output 7V/V gain output

Eddie Chou

Hi Team,

My customer test OPA855EVM with HW configuration below, however they are not able to get 7V/V gain output from Scope. the waveform from input and output is almost the same. may we know if any problem with the test configuration.

Thanks & Regards

Eddie

over 6 years ago

0 kai klaas69 over 6 years ago

Guru 140200 points

Hi Eddi,

I think this is intended. See the simulation with an ideal OPAmp:

eddie_opa855evm.TSC

Kai

0 Michael Steffes over 6 years ago in reply to kai klaas69

Guru 48395 points

Indeed, this characterization interface for broadband DC output coupling is targeting a 200ohm apparent load to the device but showing an equivalent 50ohm output impedance with that 2 resistor network. That allows flat measurement interface but does introduce an attenuation. Often, that is normalized out for datasheet plots with the thinking that normally this device is not driving a cable, but >200ohm load on a board layout.

Amplifiers

Amplifiers forum

OPA855DSGEVM: OPA855EVM doesn't output 7V/V gain output