mrf89xa Microchip Technology Inc., mrf89xa Datasheet - Page 101

• Manufacturer Part Number: mrf89xa
• Description: Ultra-low Power, Integrated Ism Band Sub-ghz Transceiver
• Manufacturer: Microchip Technology Inc.

4.4.2
The recommended PA bias and matching circuit is
illustrated in Figure 4-5.
FIGURE 4-5:
Refer to Section 4.7 “Bill of Materials” for the opti-
mized matching arrangement for each frequency band.
4.4.3
The Receiver and Transmitter share the same RFIO
pin (pin 31). Figure 4-6 illustrates the configuration of
the common RF front-end.
In Transmit mode, the PA and PA regulator are active,
with the voltage on the PARS pin equal to the nominal
voltage of the regulator (1.8V). The external inductance
is used to bias the PA.
In Receive mode, both the PA and PA regulator are
OFF and PARS is tied to ground. The RF choke induc-
tor is then used to bias the LNA.
© 2010 Microchip Technology Inc.
SUGGESTED PA BIASING AND
MATCHING
COMMON INPUT AND OUTPUT
FRONT-END
RECOMMENDED PA BIASING AND OUTPUT MATCHING
PA
PARS
RFIO
100 nH
Low-pass and DC block
Preliminary
0.047 µF
1Ω 1%
FIGURE 4-6:
To
Antenna
SAW
PARS
RFIO
DC block
FRONT-END
DESCRIPTION
Antenna
RX ON
Regulator
MRF89XA
port
(1.8V)
PA
DS70622B-page 101
LNA
PA