Part Number: OPA855
Hello,
I am in the process of developing a photon counting front-end based on an MPPC. I am shooting for a 160 MHz BW and 20 kOhm overall TIA gain. The MPPC has a 320 pF capacitance.
The conceptual design is based on a first 1 kOhm…
Part Number: OPA3S2859-EP Other Parts Discussed in Thread: ADS52J65 , OPA855-Q1 , OPA3S2859 Dear Support team,
While reading through the OPA3S2859-EP datasheet, I did not see specs included for second and third order harmonic distortion (HD2/HD3) and was…
Hi Jack,
maybe the layout was adapted from a similar layout which had removed the solid ground completely under the chip in order to prevent a short circuit to a thermal pad?
Unfortunately, the recommended layout of OPA855 you have shown is no good example…
Part Number: OPA858 Other Parts Discussed in Thread: OPA855 , LMH5401 , SN74LVC2G66-Q1 , LMH34400 I wouild like to use PSpice for TI to simulate a circuit using the OPA858 and OPA855, but the models are missing the disable function which we need to simulate…
Hello Liu,
Thank you for sharing this detailed analysis. The datasheet example is applicable in simulation. T he TIA calculator snippet from the datasheet design shows 0.092pF feedback capacitance which is very difficult to achieve in practice as seen…
Hi Stewart,
Stewart Forbes said: I forgot to mention in one of my earlier replies, but yes I have decoupling caps ( 100nF // 6u8 ) within about 10mm of the chip
I don't want to sound nitpicky or pedantic , but 10mm might be to far away from the OPAmp…
Ciao Andrea,
you might also want to have a look into this thread:
https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1089964/opa855-q1-output-layout-instruction
Kai
Hi Mia,
yes, it's standard design practise to have a solid ground plane and ground fills whereever possible. This will dramatically reduce the input to output coupling and improve the performance of the whole circuit.
Two points are important then…