CS3001

CS3002

10

DS490F9

The feedback capacitor C2 is required for closed-

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

troduces 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 17. 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

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

=