CS3011_07 Datasheet, PDF (11/18 Pages) Cirrus Logic – Precision Low-voltage Amplifier; DC to 1 kHz

CS3011
CS3012
Vin
Cin
50 pF
Vo
50 pF
Cin
R2
R1
Choose C2 so that R2 • C2 ≥ R? 1 • C_in
C2
Figure 16. Non-Inverting Gain Configuration with Compensation
The feedback capacitor C2 is required for closed- duces a pole and a zero in the loop gain transfer
loop gains greater than 50 V/V. The capacitor intro- function.
T
=
-–---^⎝⎛--1-----+------z--s---^{1---⎠⎞}-
⎛
⎝
1
+
-p-s--_{1⎠⎞}
A_o
l
P₁
=
2----π^----(^--R----₁^----1|^-|^---R----₂^---)^--C----₂^-
≅
------------1------------
2π(R₁C₂)
for
R₂ » R₁
Z₁
=
-----------------1------------------
2π(A × R₁)C₂
where
A = -R----²
R₁
Z₁
=
------------1------------
2π(R₂)C₂
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).
DS597F5
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