OPA858: current source schematic review

Hi Chi,

please give more details on the circuit. What is the input signal? What is the output current? What is the load? And ...

Is there a special reason why you choose a decompensated 5.5GHz (GBWP) OPAmp here?

Kai

Hi Kai,

the input signal is 0.3 +- 0.1V, 

the reason why customer want to use OPA858 is customer want to use one single OPA to cover all platform, OPA858 is used for TIA in optical module, this current bias is also used in optical project. the old solution is OPA855, now move to OPA858, we found that the OPA858 output current is different from OPA855. so ask your help to double check. 

BR

Chi

Hi Kai,

thanks for your simulation result. 

customer's use case,

input DC will be 0.9V, AC will be 0.3V+-0.1V

power supply is 3.3V and 5V, with 2 application scenario

output is at the node of BJT collector side. output current is 10mA

if this schematic is not stable, could you give some advice? thanks.

BR

Chi

Hi Alec,

sorry it is not a duplicated thread, my customer met a different application issue using one single OPA858. thanks. 

BR

Chi

Hello Chi,

My apologies, my dashboard for viewing threads generated a copy of your thread.  Please continue the discussion .

Best,

Alec