I assume the key parameters are the noise characteristics here. They seem to commonly quote the input noise voltage which I'm guessing gives a measure of the equivalent noise injected by the buffer itself.
Data sheets list the input noise voltage of the BUF634 as 4 nV/√Hz @ 10 kHz . There is another buffer (300 mA), the LMH6321, its datasheet claims input voltage noise 2.8 for >=10 kHz. I don't know what this means for noise at mHz.
Is there a reason we can't just buffer with more general purpose high current OP Amp? Is the the noise just a killer for that whole catalog of devices? Looking at a random selection, all the ones I've looked at have higher input noise voltage values but the digi-key product selector doesn't let me filter for noise characteristics so maybe there are low noise ones.
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The heater driver in the old design (iLIGO PSL) is this horrible programmable power supply with high output noise (see measurement of 40m PSL heater).
What we want instead is something that takes in +/- 10 V and drives a DC current (not PWM) into our heaters (which are ~50-100 Ohms). A BUF634 is almost good enough; it can do 200 mA at 10 V. Is there a BUF634 equivalent which can do more like 500 mA? Otherwise we can just use a opamp + transistor.
What is being used for the ring heaters at the LIGO sites?
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