# High negative voltages with op-amp

I am working on a project in which a very high negative voltage is required. I have the following equipment

• DC power supply with max output voltage of 300V

• Function generator with a maximum peak-to-peak voltage output of 20 Vp-p

• An electric probe, which is essentially a wire

I would need to control the electric potential of the probe using a sinusoidal waveform. For example, the waveform may have a frequency in the range of 30-50 Hz, a peak-to-peak voltage of about 150 Vp-p, and reach a DC offset of -300 V. It is important to reach voltages of about -350 V.

I was wondering if using a linear operational amplifier (op-amp) would be a doable way to create a waveform similar to the one described above.

Essentially, to use a function generator to create a signal (e.g., a sine wave of 30-50 Hz, DC offset of -20 V, peak-to-peak voltage of 20 Vp-p) and amplify the signal with an op-amp having a gain of 10. The output signal would have a same frequency, DC offset of -200 V, and peak-to-peak voltage of 200 Vp-p.

Is it possible to achieve those negative voltages with an op-amp? If yes, are there off-the-shelf op-amp able to do so?

EDIT The output current is 50 mA, at most.

• I doubt you will find off the shelf opamps for this. I'd use a discrete amp. How much output current do you need? – peufeu Apr 17 '17 at 22:48
• Apex Microtechnology makes high voltage and high power op-amps – Peter Bennett Apr 17 '17 at 22:49
• If I understand you correctly, an op-amp will not do the job. An op-amp can only output as high or low as you have supply voltages; to get an output that hits -350V you need to supply -350V (or more (as in less, say -360V) ) – Orotavia Apr 18 '17 at 3:21
• @peufeu The output current is 50 mA, at most. – Zeta Apr 18 '17 at 12:44