Yes, exactly.Run picoscope sign gen full scale (2v) to increase s/n ratio ?
Been saying you needed to pad the output for a number of posts.Already too hot for the mic input, but add in gain of 2 from the drv134 and it needs a pad.
This gives the PicoScope output its maximum S/N ratio.
When you pad the signal to get it to a usable mic level you also pad the generator noise with it.
When the DRV134/THAT1646 are fed by high impedance sources their noise level is higher.600ohm output of the sig gen into 10k input on the drv134... not sure if this is much of a problem for basic testing?
The source impedance becomes part of the internal resistor networks and unbalances it.
The cross-coupled and OutSmarts® parts have high common mode noise gain to make them work like a transformer.
When an external resistor unbalances the network some of the common mode noise gets converted to differential.
But in your case, the added noise from a 600Ω source feeding your DRV134 will be less than what you have trying to use the PicoScope ARB generator's unpadded output.
Why don't you just build a U-pad using three resistors and be done with it?
Make the middle resistor 150Ω.
7K5Ω input legs will provide about -40dB attenuation.
I would be willing to bet if you had the PicoScope ARB output drive the hot input to the pad and grounded the other input leg it will work just as well as using the DRV134 to balance it.
Hook the DUT mic input's tip and ring to the 150Ω resistor.
The PicoScope will eventually limit you owing to its 12B A/D D/A.
But it does a lot of things really well.