One of potential applications of ADA4700-1 is a piezo driver, but solutions presented in the datasheet work up to 100nF only, while my piezo has 1.5uF. Could you suggest a circuit which would work fine in such a case? I need to work with the frequencies from DC up to 35 kHz
for R = 100 Ohm and C = 1.5 uF we have fg = 1 / (2 * pi * R * C) = approx. 1 kHz, while I need 35 kHz
I would like to point out the max safe output current drive of the ADA4700-1 is about 30mA. Let's call that our peak current even if that's a bit conservative. 30mA into 1.5µF imposes an output 'slew rate' of about 0.02V/µs. At 35kHz, you would be able to get a sine wave with about 90mV peak before running into this limit. I'm assuming you will need to build a discrete power transistor output stage like Figure 68 or Figure 69 in the datasheet anyway just to get enough output current to drive your piezo.
Yes, I realize that. I need high voltage for main positioning which will be very slow (DC+). Position modulation will be very small, so that 30 mA will do.