CS3011

CS3012

DS597F5

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 the loop gain transfer

function.

This indicates that the separation of the pole and

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

required that the zero falls on the steep slope

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

there is some gain higher than 0 dB (typically 20

dB) at the hand-over frequency (the frequency at

which the slope changes from – 100 dB/decade to

–20 dB/decade).

50 pF

50 pF

R1

R2

Vin

Vo

C2

Choose C2 so that R2

• C2 ≥

?

R1

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

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

=