Powering multiple optical front-ends

[Pavel_47]

Hello,

There are 8 optical front-ends on the board ... the front-ends based on TSV771 (or TSV772, TSV782, TSV791, TSV792).

Is it important to use one LDO per front-end or powering all 8 frontends by a single LDO will be also Ok ?

Thanks.

[Peter BENSCH]

Even if the opamps are used as transimpedance amplifiers, separate LDOs are not necessarily an advantage because their PSRR and its frequency dependence play a major role and should also be taken into account. Without knowing your application in detail, it might make sense in your case to use a single LDO and separate the supply voltages of the individual opamps cleanly with LC filters and a carefully designed layout including GND.

Hope that helps?

Good luck!
/Peter

[Pavel_47]

Hi Peter

Thanks. Considering that the PSRR is quite high at low frequencies and damps at high frequencies, perhaps ferrite beads would be sufficient to separate the VDDs of OpAmps ?

[Peter BENSCH]

As I said, I don't know the circuit or the necessary parameters, but I assume that ferrite beads could be a bit scarce because their inductance is usually quite small. Perhaps a simulation or a test could be useful.

For the capacitors, MLCCs might be the best choice.

[Pavel_47]

Ok, thanks Peter.