The Bias of an Inverting Amplifier

TSH310

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7 The Bias of an Inverting Amplifier

A resistance is necessary to achieve a good input biasing, such as resistance R shown in Figure 30.

The magnitude of this resistance is calculated by assuming the negative and positive input bias current.

The aim is to compensate for the offset bias current, which could affect the input offset voltage and the

Figure 30: Compensation of the input bias current

R

R

in

R

fb

×

R

in

R

+

fb

-----------------------

=

R

Load

Output

Ib-

Ib+

Vcc+

Vcc-

+

_

R

Load

Output

Ib-

Ib+

Vcc+

Vcc-

+

_