Operational Amplifier Circuits

88 OPERATIONAL

AMPLIFIER

CIRCUITS:

ANALYSIS

AND

DESIGN

2.

Those that exploit the inherent nonlinear characteristic of a particular

device. In particular, the bipolar transistor is widely used to generate logarith-

mic and antilogarithmic functions, as discussed in Section 6.6.

6.2

Simple

Limiting

The transfer characteristic of an ideal limiter is shown in Figure 6-1. For input

signals between V

Li

_ and V

L/+

, the output V

Q

is directly proportional to V

i

with a

gain that may be selected in the usual way. For inputs exceeding these values,

the output remains constant at the appropriate value of or V^

+

. Circuits of

this kind are particularly useful ...