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

[Michael Zacherl]

On 28.Jan 2016, at 13:36 , Roman Sowa <modular at go2.pl> wrote:

> In high gain application it's better to split to 2 opamps, this way you get much higher bandwidth than when done on single opamp.
> For example if 60dB gain on one opamp would have 3dB bandwidth ending at about 10kHz, while 30+30dB on 2 opamps of the same kind it jumps over 300kHz.

hm .. so what’s the impact on the SNR?

> W dniu 2016-01-28 o 13:03, Mattias Rickardsson pisze:
>> 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?


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