We were earlier using OPA4340 (CMOS fabricated) for Shock detection application, but now we want to go with another part, but unable to compare input impedance in terms of Ω || pF.
As most of the data sheet comes with parameter like INPUT CAPACITANCE -Common-Mode Input Capacitance, Differential Input Capacitance.
Kindly tell how to convert it to Ω || pF. or how to compare it with input impedance.
thanks
Hi Tarun,
I'm not sure I understand your question. OPA4340 specifies all four parameters of the Input Impedance (see below).
Rin_diff=10Tohm, Cin_diff=3pF
Rin_cm=10Tohm, Cin_cm=6pF
If the part you plan on using ONLY specifies Cin_diff and Cin_cm but no Rin_diff and Rin_cm, for CMOS input op amps it is safe to assume them to be above 1Tohm.
If you have further question, please specify what exact part you wish to use.
