MAX2450 Datasheet, PDF (1/8 Pages) Maxim Integrated Products – 3V, Ultra-Low-Power Quadrature Modulator/Demodulator

19-0455; Rev 1; 9/98
EVAALVUAAILTAIOBNLEKIT
3V, Ultra-Low-Power Quadrature
Modulator/Demodulator
General Description
The MAX2450 combines a quadrature modulator and
quadrature demodulator with a supporting oscillator and
divide-by-8 prescaler on a monolithic IC. It operates
from a single +3V supply and draws only 5.9mA. The
demodulator accepts an amplified and filtered IF signal
in the 35MHz to 80MHz range, and demodulates it into I
and Q baseband signals with 51dB of voltage conver-
sion gain. The IF input is terminated with a 400Ω thin-
film resistor for matching to an external IF filter. The
baseband outputs are fully differential and have 1.2Vp-p
signal swings. The modulator accepts differential I and
Q baseband signals with amplitudes up to 1.35Vp-p
and bandwidths to 15MHz, and produces a differential
IF signal in the 35MHz to 80MHz range.
Pulling the CMOS-compatible ENABLE pin low shuts
down the MAX2450 and reduces the supply current to
less than 1µA. To minimize spurious feedback, the
MAX2450’s internal oscillator is set at twice the IF via
external tuning components. The oscillator and associ-
ated phase shifters produce differential signals exhibit-
ing low amplitude and phase imbalance, yielding
modulator sideband rejection of 38dB. The MAX2450
comes in a QSOP package.
Applications
Digital Cordless Phones
GSM and North American Cellular Phones
Wireless LANs
Digital Communications
Two-Way Pagers
Pin Configuration
TOP VIEW
IF_OUT ₁
IF_OUT ₂
GND ₃
I_IN ₄
I_IN ₅
Q_IN ₆
Q_IN 7
ENABLE 8
PRE_OUT ₉
LO_V_{CC 10}
MAX2450
20 ^IF_IN
19 ^GND
18 ^VCC
17 I_OUT
16 I_OUT
15 Q_OUT
14 Q_OUT
13 LO_GND
12 TANK
11 TANK
____________________________Features
o Combines Quadrature Modulator and
Demodulator
o Integrated Quadrature Phase Shifters
o On-Chip Oscillator (Requires External Tuning
Circuit)
o On-Chip Divide-by-8 Prescaler
o Modulator Input Bandwidth Up to 15MHz
o Demodulator Output Bandwidth Up to 9MHz
o 51dB Demodulator Voltage Conversion Gain
o CMOS-Compatible Enable
o 5.9mA Operating Supply Current
1µA Shutdown Supply Current
Ordering Information
PART
MAX2450CEP
TEMP. RANGE
0°C to +70°C
PIN-PACKAGE
20 QSOP
Functional Diagram
IF_IN ²⁰
400Ω
DEMODULATOR
17
I _OUT
16
I_OUT
BIAS
15
Q_OUT
14
Q_OUT
LO_V_CC ¹⁰
TANK ¹¹
TANK ¹²
LO_GND ¹³
I_IN ⁴
I_IN ⁵
Q_IN ⁶
Q_IN ⁷
V_CC ¹⁸
÷ 2 ^0°
QUADRATURE
PHASE
GENERATOR
LOCAL
OSCILLATOR
÷ 2 ^90°
÷4
PRESCALER
MAX2450
MODULATOR
Σ
MASTER BIAS
BANDGAP
BIAS
9
PRE_OUT
1
2 ^IF_OUT
IF_OUT
QSOP
3, 19
GND
8
ENABLE
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