Silicon Laboratories EFR32xG14 Wireless Gecko Reference Manual page 806

POS0
+
-
VIN
R1
R2
Table 24.8 Cascaded Inverting PGA Configuration on page 806
output from OPA0 is connected to OPA1 to create the second stage by setting the RESINMUX field to OPANEXT in
VDACn_OPA1_MUX. The last stage is created by setting the RESINMUX bit-field to OPANEXT in VDACn_OPA2MUX.
OPA
OPA0
OPA0
OPA0
OPA1
OPA1
OPA1
OPA2
OPA2
OPA2
24.3.4.6 Cascaded Non-inverting PGA
This mode enables the opamp signals to be internally configured to cascade two or more opamps in non-inverting mode as shown in
Figure 24.8 Cascaded Non-inverting PGA Overview on page
ladder by setting the NEGSEL bit-field to OPATAP. In addition the resistor ladder input must be set to VSS or NEGPADx by configuring
the RESINMUX bit-field in VDACn_OPAx_MUX.
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POS1
+
-
R1
R2
VOUT1=-(VIN-POS0) x R2/R1 + POS0
Figure 24.7. Cascaded Inverting PGA Overview
shows cascaded non-inverting PGA with OPA0,OPA1 and OPA2. The
Table 24.8. Cascaded Inverting PGA Configuration
OPA Bitfields
POSSEL
NEGSEL
RESINMUX
POSSEL
NEGSEL
RESINMUX
POSSEL
NEGSEL
RESINMUX
807. The negative input for all opamps will be connected to the resistor
POS2
+
-
R1
R2
VOUT2=-(VOUT1-POS1) x R2/R1 + POS1
OPA Configuration
POSPAD0, APORT[1-4]X
OPATAP
NEGPAD0
POSPAD1, APORT[1-4]X
OPATAP
OPANEXT
POSPAD2,APORT[1-4]X
OPATAP
OPANEXT
Reference Manual
OPAMP - Operational Amplifier
VOUT3=-(VOUT2-POS3) x R2/R1 + POS3
Rev. 1.1 | 806