MAX2769ETI+T Maxim Integrated Products, MAX2769ETI+T Datasheet - Page 22

• Manufacturer Part Number: MAX2769ETI+T
• Description: RF Receiver Low-Power GPS and GL ONASS Receiver with
• Manufacturer: Maxim Integrated Products

Specifications of MAX2769ETI+T

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PROCESS: SiGe BiCMOS
The LNA and mixer inputs require careful consideration
in matching to 50Ω lines. Proper supply bypassing,
grounding, and layout are required for reliable perfor-
mance from any RF circuit.
The MAX2769 can be operated in a low-power mode
by programming the bias current values of individual
blocks to their minimum recommended values. The list
below summarizes the recommended changes to serial
interface registers from their default states to achieve a
low-power operation:
In this mode, LNA, mixer, LO, and VCO currents are
reduced to their minimum recommended values. The IF
filter is configured as a 3rd-order filter. The output data
is in a 1-bit CMOS mode in the I channel only. PLL is in
an integer-N power-saving mode, which can be used if
the main division ratio is divisible by 32. The antenna
bias circuitry is disabled.
In the low-power mode, the total current consumption
reduces to 10mA, while the total cascaded noise figure
increases to 3.8dB.
The use of the wideband receiver options is recom-
mended for Galileo and GLONASS applications. The
frequency synthesizer is used to tune LO to a desired
frequency, which, in turn, determines the choice of the
Universal GPS Receiver
22
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ILNA1 = 0010
ILNA2 = 00
ILO = 00
IMIX = 00
F3OR5 = 1
ANTEN = 0
BITS = 000
IVCO = 0
REFOUTEN = 0
PLLPWRSAV = 1
Operation in Wideband Galileo and
Applications Information
GLONASS Applications
Chip Information
Low-Power Operation
IF center frequency. Either a fractional-N or an integer-
N mode of the frequency synthesizer can be used
depending on the choice of the reference frequency.
For Galileo reception, set the IF filter bandwidth to
4.2MHz (FBW = 10) and adjust the IF center frequency
through a control word FCEN to the middle of the down-
converted signal band. Alternatively, use wideband set-
tings of 8MHz and 18MHz when the receiver is in a
zero-IF mode.
For GLONASS as well as GPS P-code reception, a
zero-IF receiver configuration is used in which the IF fil-
ter is used in a lowpass filter mode (FCENX = 1) with a
two-sided bandwidth of 18MHz.
It is recommended that an active antenna LNA be used
in wide-bandwidth applications such that the PGA is
operated at lower gain levels for a maximum band-
width. If a PGA gain is programmed directly from a seri-
al interface, GAININ values between 32 and 38 are
recommended. Set the filter pole at the mixer output to
36MHz through MIXPOLE = 1.
The MAX2769 EV kit can be used as a starting point for
layout. For best performance, take into consideration
grounding and routing of RF, baseband, and power-
supply PCB proper line. Make connections from vias to
the ground plane as short as possible. On the high-
impedance ports, keep traces short to minimize shunt
capacitance. EV kit Gerber files can be requested at
www.maxim-ic.com.
To minimize coupling between different sections of the
IC, a star power-supply routing configuration with a large
decoupling capacitor at a central V
mended. The V
going to a separate V
bypass capacitor as close as possible to each supply
pin This arrangement provides local decoupling at each
V
low-inductance ground connection. Do not share the
capacitor ground vias with any other branch.
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages.
CC
PACKAGE TYPE
28 TQFN-EP
pin. Use at least one via per bypass capacitor for a
WAFER
CC
traces branch out from this node, each
PACKAGE CODE
Package Information
CC
T2855+3
WDICE8
node in the circuit. Place a
Power-Supply Layout
CC
Layout Issues
DOCUMENT NO.
node is recom-
21-0140
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