OPamp recommendation

Carsten Koeck

Other Parts Discussed in Thread: THS4021, THS3120, THS3091

Dear amplifier experts,

I am looking for an OP:

- high input impedance (>1MOhm)

- low input capacitance (<1pF)

- GBW > 10MHz

- Noise < 5nV/sqrt(Hz)

- Input voltage +/- 10V

THS4021 comes close but input capacitance is at 1.5pF

Any other ideas would be highly appreciated!

0 kai klaas69 over 3 years ago

Guru 140200 points

Hi Carsten,

less than 1pF can hardly be achieved because of unavoidable stray capacitance within the chip.

What supply voltage are we talking about? A schematic would be helpful.

Kai

0 Michael Steffes over 3 years ago in reply to kai klaas69

Guru 48395 points

Kai is correct, one of the things comes along with lower input noise is larger input device - higher C.

0 Sima Jalaleddine over 3 years ago

Hi Carsten,

Also, what is the intended gain of the circuit? The THS4021 is decompensated which means it is stable at gains of 10 (-9) or greater.

Thank you,

Sima

+1 Carsten Koeck over 3 years ago

Gentlemen, thanks for your input.

I have recommended to use either THS3091 or THS3120.

Of course the customer will have to take care of a proper layout to achieve the desired input capacitance!

Best regards

Carsten

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