Datasheet

External 1- F
Noise Reduction Capacitor
m
PA_V
S
R
R
PA_GND
Inside the AFE030
4 kW
PA_V
2
S
Bias
Internal
REF1
AVDD
2
External 1-nF
Noise Reduction Capacitor
AVDD
R
R
AGND
Inside the AFE030
4 kW
BiasInternal
REF2
AFE030
www.ti.com SBOS588A –DECEMBER 2011– REVISED DECEMBER 2011
REF1 and REF2 Blocks
The REF1 and REF2 blocks create midscale power-supply biasing points used internally to the AFE030. Each
reference divides its respective power-supply voltage in half with a precision resistive voltage divider. REF1
provides a PA_V
S
/2 voltage at the output of the PA, while REF2 provides an AV
DD
/2 voltage at the outputs of the
Tx PGA, Tx Filter, Rx PGA1, Rx Filter, and Rx PGA2. Each REF block has its output brought out to an external
pin that can be used for filtering and noise reduction. Figure 36 and Figure 37 show the proper connections of
the external noise-reducing capacitors. These capacitors are optional, but are recommended for best
performance.
Figure 36. REF1 Functional Diagram
Figure 37. REF2 Functional Diagram
Copyright © 2011, Texas Instruments Incorporated 31
Product Folder Link(s): AFE030