Cirrus Logic AN300 REV1 - Manual (Page 7)

AN300REV1 7
AN300
inside the Cirrus Logic CS3001/2/11/12 amplifiers. Note that although not shown in the diagram, the signal is
chopped as a differential signal.
Figure 9. Block Diagram of Cirrus Logic’s Multipath Chopper-stabilized Amplifier, CS3001/02/11/12
The "multi-path" approach to these amplifiers was used to achieve 300 dB of open loop gain. These amplifiers can
be made stable for gains higher than 50X with a single feedback capacitor. They offer significant improvement over
competing amplifiers when an amplifier with low noise, low offset drift and very high open loop gain is required for
an application.
Figure 10 illustrates the open loop gain and phase of the CS3001/2/11/12 amplifiers. Figure 11 illus-
trates an expanded view of the region of the open loop gain and phase above 10 kHz.
Figure 10. Open-loop Gain and Phase vs. Frequency, CS3001/02/11/12
AMP1
AMP2
AMP3
AMP4
AMP5
V
IN
V
OUT
High-frequency Path
φ1 φ1
Gain
Phase