CS3011

CS3012

DS597F6

11

The feedback capacitor C2 is required for closed-

loop gains greater than 50 V/V. The capacitor intro-

duces a pole and a zero in th e loop gain transfer

function.

This indicates that the sep aration of the pole and

the zero is governed by the closed loop gain. It is

required that th e ze ro falls o n the steep slo pe

(–100 dB/decade) of the loop ga in plot so that

there is some gain higher than 0 dB (typically 20

dB) at the ha nd-over frequency (the frequ ency at

which the slope changes from – 100 dB/decade to

–20 dB/decade).

50 pF

50 pF

R1

R2

Vin

Vo

C2

Figure 16. Non-Inverting Gain Configuration with Compensation

T

1

s

z

1

-----

+





–

1

s

p

1

-----

+





-----------------------A

ol

=

P

1

1

2

π R

1

R

2

||

()C

2

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

1

2

π R

()

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

≅

=for

R

2

R

1

»

Z

1

1

2

π AR

1

×

()C

2

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

=where

A

R

2

R

1

------

=

Z

1

1

2

π R

2

()C

2

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

=