[sdiy] Spare op-amp useful in gain stage?

[Mattias Rickardsson]

Hi!

I was in a discussion about what to do with a spare OP-amp. These
fellows come in duals and quads, and sometimes the quantities don't
end up perfectly and you stand there with an extra unused op-amp.

Is there any clever way of using two op-amps instead of one in, say, a
noisy high-gain stage in order to reach lower noise or something like
that?

Douglas Self's small signal book suggests paralleling two gain stages
("multipath amplifiers"), having their outputs tied together with 10
ohms to the destination, winning 3 dB SNR. Are there other clever ways
of using a spare op-amp, particularly in a stage with high gain?

/mr