CS3001
CS3002
V in
Cin
50 pF
50 pF
Vo
Cin
R2
C2
R1
Choose C2 so that R2C2
R1Cin
Figure 11. Non-Inverting Gain Configuration with Compensation
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).
s
– 1 + ----
z1
-----------------------
T =
Aol
s
1 + -----
p1
1
1
------------------------------------ ------------------------
P1
=
≅
for
R2 » R1
||
2π(R1 R2)C2 2π(R1C2)
R
1
Z1 = -----------------------------------
where
A = ----2-
R1
2π(A × R1)C2
9
CIRRUS [ CIRRUS LOGIC ]
