Digital potentiometer to set the gain of an op amp?

[helloThere]

Just curious because I'm working on a piezo driver/receiver and was thinking about for another revision having the receive operational amplifier use a digital potentiometer to have more flexible gain control depending on the piezo element. Is this done very often for gain control?

[nfmax]

Not quite a digital potentiometer, but I used the equivalent in, as it happens, a piezoelectric ultrasound transducer receiver:
https://www.eevblog.com/forum/projects/programmable-gain-amplifier-flat-to-10-mhz/msg5617787/#msg5617787

It works well

[mikerj]

You can use a digipot to adjust gain, but pay close attention to their very limited bandwidth.

[Benta]

Not to mention taking care of DC levels. A digi pot doesn't float like a passive pot.

[Kleinstein]

The digital pots have a somewhat limited BW. The frequency range for ulrasound is quite large and it would only be the low end to work well with digital pots. Usually one does no need very fine adjustments and porpose build PGA type amplifiers with more corse gain steps may be the better solution.
For fine adjust some multiplying DACs are a good alternative too.

Many of the digital pots can float (no direct link to ground), but need to be used within the supply limites.

[coppercone2]

how about jfets

[Terry Bites]

As Kleinstein says, the terminal capacitance of these things will severely limit the hf response.
But see this www.analog.com/en/resources/technical-articles/how-to-increase-the-bandwidth-of-digital-potentiometers-10x-to-100x.html
This may interest you www.edn.com/dpot-pseudolog-log-lookup-table-actual-logarithmic-gain

A wideband VGA or PGA is probably the simplest solution. 10-100's Hz bandwidth.
Many of them are cheaper than an a digipot wideband amp combination! eg a MAX3523 PGA or or if you still want to use the digipot as the gain control something like a LMH6503 VGA would work well.
Also consider analog multipliers as wideband VGAs.

www.analog.com/en/parametricsearch/11327#/sort=s3,asc]https://www.analog.com/en/parametricsearch/11327#/sort=s3,asc
www.ti.com/amplifier-circuit/pga-vga/products.html]https://www.ti.com/amplifier-circuit/pga-vga/products.html