RF2498PCBA-41X View Datasheet(PDF) - RF Micro Devices
Part Name
Description
MFG CO.
'RF2498PCBA-41X' PDF : 22 Pages View PDF
RF2498
Pin Function Type Description
28 GPS MIX IN AI GPS mixer RF single-end input.
Interface Schematic
GPS MIX IN
29
30
31
32
Pkg
Base
Legend:
VCC1
ISET1
ISET2
ISET3
GND
P DC supply for internal reference, logic control, cellular mixer
preamp, and GPS mixer preamp (PCS mixer preamp has its’ own
DC supply, PCS_RFA_VCC). External bypass capacitor between
1nF and 47nF required.
AO Resistor for internal voltage reference setting. Recommended
value 5.1kΩ.
AO Resistor to ground sets the LNA current in boost mode (all three
LNAs). Higher resistance results in lower current.
AO Resistor to ground sets preamp and mixer currents in all bands.
Higher resistance results in lower currents.
P Ground connection. The backside of the package should be sol-
dered to a top side ground pad which is connected to the ground
plane with multiple vias.
DI=Digital Input from Baseband Chip
AI=Analog Input
AO=Analog Output
P=VCC or GND
ISET Pins
ISET1 sets the internal reference voltage for the bias control circuits to all functional blocks. An external resistor of 5.1kΩ to
ground is required. We do not recommend adjusting this resistor value. This resistor is pulled out to allow for a higher precision
off chip value and not as a significant tuning adjustment.
ISET2 sets the DC current through the LNAs in all bands when IPSET is high. Higher resistance to ground results in lower cur-
rent through the LNA. Increasing the LNA current will improve the IIP3 of the LNA and slightly increase gain in all modes. NF
typically will get worse as you increase current. Increasing the LNA current in one mode, i.e. Cellular, will also increase the LNA
current for the high IPSET state for PCS and the GPS LNAs as well.
ISET3 sets the DC current through the mixer and mixer preamplifier for all bands. Higher resistance to ground results in lower
current. Lower current will improve mixer NF but will degrade IIP3. Mixer and the mixer preamp gain is not significantly changed
with current.
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7628 Thorndike Road, Greensboro, NC 27409-9421 · For sales or technical
support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com.
Rev A3 DS030711
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