RF3854PCBA View Datasheet(PDF) - RF Micro Devices
Part Name
Description
MFG CO.
'RF3854PCBA' PDF : 26 Pages View PDF
Pin Function Description
1
VCC2
Supply for LO buffers, frequency doubler and dividers.
RF3854
Interface Schematic
VCC2
Modulator and
VGA
2
LO HB P High band local oscillator input (1800MHz).
In “low band FLO/2” modes the signal (LOHBP-LOHBN) undergoes a fre-
quency division of 2 to provide the low band LO signal for the modulator.
VCC
In “high band FLOx1” modes the signal (LOHBP-LOHBN) is used as the
high band LO signal for the modulator.
In “high band bypass” a modulated DCS1800/PCS1900 signal (LOHBP-
LOHBN) is switched into the RF signal path. The modulator is disabled and
the signal is routed to the RFOutHb outputs through a differential PA driver
amplifier.
LO HB P
The LOHBP input is AC-coupled internally.
The noise performance, carrier suppression at low output powers and side-
band suppression all vary with LO power. The optimum LO power is
LO HB N
between -3dBm and +3dBm. The device will work with LO powers as low as
-20dBm however this is at the expense of higher phase noise in the LO cir-
cuitry and poorer sideband suppression.
The input impedance should be externally matched to 50Ω. The port can
be driven either differentially or single ended. The port impedance does
not vary significantly between active and power down modes.
3
LO HB N The complementary LO input for both LOHBP LO signals.
See pin 2.
In any of the modes the LOHB input may be driven either single ended or
differentially. If the LO is driven single ended then the PCB board designer
can ground this pin.
It is recommended that if this pin is grounded that it is kept isolated from
the GND1 pin and the die flag ground. All connections to any other ground
should be made through a ground plane. Poor routing of this ground signal
can significantly degrade the LO leakage performance.
4
LO LB P Low band local oscillator input (900MHz).
In “wideband FLOx2” and “high band FLOx2” modes the signal (LOLBP-
LOLBN) is doubled in frequency to provide the LO signal for the modulator.
VCC
In “Low band FLOx1” modes the signal (LOLBP-LOLBN) is used as the LO
signal for the modulator.
In “Low band Bypass” a modulated GSM900 signal (LOLBP-LOLBN) is
switched into the RF signal path. The modulator is disabled and the signal
is routed to the RFOutLb outputs through a differential PA driver amplifier.
This LOLBP input is AC-coupled internally.
The noise performance, carrier suppression at low output powers and side- LO LB P
band suppression performance are functions of LO power. The optimum LO
power is between -3dBm and +3dBm. The device will work with LO powers LO LB N
as low as -20dBm however this is at the expense of higher noise perfor-
mance at high output powers and poorer sideband suppression.
The input impedance should be externally matched to 50Ω. The port
impedance does not vary significantly between active and powered modes.
5
LO LB N The complementary LO input for both LOLBP LO signals.
See pin 4.
In any of the modes the LOLB input may be driven either single ended or
differentially. If the LO is driven single ended then the PCB board designer
can ground this pin.
It is recommended that if this pin is grounded that it is kept isolated from
the GND1 pin and the die flag ground. All connections to any other ground
should be made through a ground plane. Poor routing of this GndLO signal
can significantly degrade the LO leakage performance.
Rev A1 DS070313
7628 Thorndike Road, Greensboro, NC 27409-9421 · For sales or technical
support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com.
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