19-0493; Rev 0; 12/95
3 V, Ult ra -Lo w -P o w e r
Qu a d ra t u re De m o d u la t o r
MAX2451
_______________Ge n e ra l De s c rip t io n
____________________________Fe a t u re s
The monolithic MAX2451 is a quadrature demodulator
with a supporting oscillator and divide-by-8 prescaler. It
operates from a single +3V supply and draws only
5.5mA. The demodulator accepts an amplified and fil-
tered IF signal in the 35MHz to 80MHz range, and
demodulates it into I and Q baseband signals with
51dB of voltage conversion gain. The IF input is termi-
nated with a 400Ω thin-film resistor for matching to an
external IF filter. The baseband outputs are fully differ-
ential and have 1.2Vp-p signal swings.
♦ Integrated Quadrature Phase Shifters
♦ On-Chip Oscillator (Requires External Tuning
Circuit)
♦ 51dB Voltage Conversion Gain
♦ On-Chip Divide-by-8 Prescaler
♦ Baseband Output Bandwidth Up to 9MHz
♦ CMOS-Compatible Enable
Pulling the CMOS-compatible ENABLE pin low shuts
down the MAX2451 and reduces the supply current to
less than 2µA, typical. To minimize spurious feedback,
the MAX2451’s internal oscillator is set at twice the IF
fre q ue nc y via e xte rna l tuning c omp one nts . The
MAX2451 comes in a 16-pin narrow SO package.
♦ 5.5mA Operating Supply Current
2µA Shutdown Supply Current
______________Ord e rin g In fo rm a t io n
________________________Ap p lic a t io n s
Digital Cordless Phones
PART
TEMP. RANGE
PIN-PACKAGE
MAX2451CSE
0°C to +70°C
16 Narrow SO
GSM and North American Cellular Phones
Wireless LANs
Digital Communications
Pagers
________________Fu n c t io n a l Dia g ra m
14
I
13
__________________P in Co n fig u ra t io n
I
DEMODULATOR
1
IF
BIAS
12
11
TOP VIEW
Q
Q
400Ω
IF
GND
1
2
3
4
5
6
7
8
GND
16
15
14
13
12
0°
6
7
8
V
CC
÷ 2
÷ 4
LO_V
PRE_OUT
CC
PRESCALER
TANK
QUADRATURE
PHASE
GENERATOR
GND
I
9
TANK
N.C.
MAX2451
I
10
90°
÷ 2
LOCAL
LO_GND
MAX2451
ENABLE
PRE_OUT
Q
OSCILLATOR
15
11
10
9
Q
V
CC
MASTER BIAS
LO_V
CC
LO_GND
TANK
BANDGAP
BIAS
TANK
2, 3, 16
GND
5
SO
ENABLE
________________________________________________________________ Maxim Integrated Products
1
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