Figure 171. Pga Mode, Internal Gain Setting (X2/X4/X8/X16/X32/X64); Inverting Input Used For Filtering - ST STM32G4 Series Reference Manual

Operational amplifiers (OPAMP)
Programmable gain amplifier mode with external filtering
The procedure to use the OPAMP to amplify the amplitude of an input signal, with an
external filtering, is presented hereafter.
•
configure VM_SEL bits as "Feedback resistor is connected to OPAMPx_VINM input",
10
• configure PGA_GAIN bits as "internal Gain 2, 4, 8, 16, 32 or 64 with filtering on
VINM0", 10000 to 10101
•
configure VP_SEL bits as "GPIO connected to OPAMPx_VINP".
Any external connection on VINM can be used in parallel with the internal PGA, for
example a capacitor can be connected between opamp_out and VINM for filtering
purpose (see datasheet for the value of resistors used in the PGA resistor network).
VINP3 or DACx_CHy
Allows optional
low-pass
filtering
1. opamp_out can be redirected internally to an ADC channel by setting OPAINTOEN bit.
In this case, the I/O on which is mapped the OPAMPx_VOUT is free and can be used for another purpose.
1. The gain depends on the cut-off frequency.
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Figure 171. PGA mode, internal gain setting (x2/x4/x8/x16/x32/x64),

inverting input used for filtering

STM32
VINP0
VINP1
VINP2
INM0
(1)
VOUT
+
-
Equivalent to
RM0440 Rev 1
RM0440
(1)
opamp_out
MSv48042V1