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Why input resistance not described in an operational amplifier sheet?

Latest Updated:12/01/2011

Question:

Why is "input resistance" not described in the operational amplifier data sheets?

Answer:

The input resistance (Ω) can be calculated as R = V/I per unit voltage (1 V) from the input bias current (A) described in the electrical specifications in the data sheets.

An example using the uPC151 is shown

  MIN. TYP. MAX. Unit
Input bias current - 80 500 nA
Input resistance 2 12.5 -
Suitable Products
Operational Amplifiers
USB2.0 Host/Peripheral Controller
UPD720150