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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 400
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
____________________________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
MAX2450
3V, Ultra-Low-Power Quadrature
Modulator/Demodulator
________________________________________________________________
Maxim Integrated Products
1
ENABLE
GND
400
2
IF_OUT
1
8
3, 19
IF_OUT
9
PRE_OUT
14
Q_OUT
15
Q_OUT
16
I_OUT
17
I _OUT
20
IF_IN
10
LO_V
CC
11
TANK
12
TANK
4
I_IN
5
I_IN
6
Q_IN
7
Q_IN
18
V
CC
13
LO_GND
BIAS
PRESCALER
MODULATOR
DEMODULATOR
QUADRATURE
PHASE
GENERATOR
LOCAL
OSCILLATOR
÷
2
÷
4
BANDGAP
BIAS
MASTER BIAS
÷
2
0°
90°
MAX2450
Functional Diagram
20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
IF_IN
GND
V
CC
I_OUT
I_OUT
Q_OUT
Q_OUT
LO_GND
TANK
TANK
IF_OUT
IF_OUT
GND
I_IN
I_IN
Q_IN
Q_IN
ENABLE
PRE_OUT
LO_V
CC
TOP VIEW
12
11
9
10
QSOP
MAX2450
Pin Configuration
19-0455; Rev 1; 9/98
PART
MAX2450CEP
0°C to +70°C
TEMP. RANGE
PIN-PACKAGE
EVALUATION KIT
AVAILABLE
Ordering Information
20 QSOP
MAX2450
3V, Ultra-Low-Power Quadrature
Modulator/Demodulator
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
DC ELECTRICAL CHARACTERISTICS
(
V
CC
=
LO_V
CC
= TANK =
2.7V to 3.3V, ENABLE = V
CC
- 0.4, GND = LO_GND = 0V, I_IN = I_IN = Q_IN = Q_IN = IF_IN = TANK =
OPEN, T
A
= 0°C to +70°C, unless otherwise noted.)
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
V
CC
, LO_V
CC
to GND............................................-0.3V to +4.5V
ENABLE, TANK, TANK, I_IN, I_IN, Q_IN,
Q_IN to GND ..................................................-0.3V to (V
CC
+ 0.3V)
IF_IN to GND .........................................................-0.3V to +1.5V
Continuous Power Dissipation (T
A
= +70°C)
QSOP (derate 9.1mW/°C above +70°C) ......................727mW
Operating Temperature Range...............................0°C to +70°C
Storage Temperature Range .............................-65°C to +165°C
Lead Temperature (soldering, 10sec) .............................+300°C
ENABLE = 0.4V
ENABLE = V
CC
CONDITIONS
V
1.2
V
I_OUT/I_OUT
,
V
Q_OUT/Q_OUT
I_OUT, I_OUT, Q_OUT, Q_OUT
DC Bias Voltage Level
µA
2
20
I
CC(OFF)
Shutdown Supply Current
mA
5.9
8.2
I
CC(ON)
V
2.7
3.3
V
CC
, LO_V
CC
Supply Voltage Range
Supply Current
320
400
480
Z
IF_IN
Demodulator IF Input Impedance
V
V
CC
- 1.5
V
IF_OUT/IF_OUT
IF_OUT, IF_OUT DC Bias Voltage
k
35
44
Z
I_IN/I_IN
,
Z
Q_IN/Q_IN
Modulator Differential Input
Impedance
V
1.25
1.5
1.75
V
I_IN/I_IN
,
V
Q_IN/Q_IN
I_IN, I_IN, Q_IN, Q_IN
Self-Bias DC Voltage Level
µs
10
t
ON/OFF
Enable/Disable Time
µA
1
3
I
EN
ENABLE Bias Current
V
V
CC
- 0.4
V
ENH
ENABLE High Voltage
V
0.4
V
ENL
ENABLE Low Voltage
UNITS
MIN
TYP
MAX
SYMBOL
PARAMETER
AC ELECTRICAL CHARACTERISTICS
(MAX2450 EV kit, V
CC
= LO_V
CC
= ENABLE = 3.0V, f
LO
= 140MHz, f
I_IN
/
I_IN
= f
Q_IN/Q_IN
= 600kHz, V
I_IN/I_IN
= V
Q_IN/Q_IN
= 1.2Vp-p,
f
IF_IN
= 70.1MHz, V
IF_IN
= 2.82mVp-p, T
A
= +25°C, unless otherwise noted.)
(Note 2)
(Note 2)
CONDITIONS
dB
< ±0.45
I and Q Amplitude Balance
dBc
-60
IM5
I/Q
I and Q IM5 Level
dBc
-44
IM3
I/Q
I and Q IM3 Level
degrees
< ±1.3
I and Q Phase Accuracy
dB
51
Voltage Conversion Gain
UNITS
MIN
TYP
MAX
SYMBOL
PARAMETER
R
L
= 10k
, C
L
< 6pF, rising edge
(Notes 1, 3)
10kHz offset
R
L
= 10k
, C
L
< 6pF
MHz
9
BW
DEMOD
I and Q Signal 3dB Bandwidth
V/µs
60
SR
PRE_OUT
PRE_OUT Slew Rate
MHz
70
160
f
LO
Oscillator Frequency Range
dBc/Hz
-80
LO Phase Noise
V
p-p
0.35
V
PRE_OUT
PRE_OUT Output Voltage
(Note 1)
V
p-p
1.35
Allowable I and Q Voltage Swing
mV
±11
±50
Demodulator I and Q Baseband
DC Offset
dB
18
NF
Noise Figure
DEMODULATOR
MAX2450
3V, Ultra-Low-Power Quadrature
Modulator/Demodulator
_______________________________________________________________________________________
3
7.0
6.8
6.6
6.4
6.2
6.0
5.8
5.6
5.4
5.2
5.0
0
10
20
30
40
50
60
70
80
MAX2450-01
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
SUPPLY CURRENT
vs. TEMPERATURE
V
CC
= 2.7V
V
CC
= 3.3V
V
CC
= 3.0V
0
2
4
6
8
10
12
0
10
20
30
40
50
60
70
80
MAX2450-02
TEMPERATURE (°C)
V
CC
= 2.7V
V
CC
= 3.3V
V
CC
= 3.0V
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
SUPPLY CURRENT (
µ
A)
-30
-34
-38
-42
-46
-50
-54
-26
-22
-18
-14
-10
-6
MAX2450-03
BASEBAND INPUT (dBV
RMS
)
OUTPUT (dBV
RMS
)
MODULATOR IF OUTPUT
vs. BASEBAND INPUT
Vp-p = 2 2 x 10
(V)
dBV
RMS
20
(Note 1)
V
I_IN/I_IN
, = V
Q_IN/Q_IN
= 1.2Vp-p,
R
L
= 200k
differential,
C
L
< 5pF differential
V
I_IN/I_IN
= 1.35Vp-p composite
(Note 4)
V
I_IN/I_IN
= 1.35Vp-p composite
(Note 4)
CONDITIONS
V
1.25
1.75
Input Common-Mode Voltage Range
V
p-p
1.35
V
I_IN/I_IN
,
V
Q_IN/Q_IN
Allowable Differential Input Voltage
dBc
-36
Carrier Suppression at Modulator
Output
dBc
38
Sideband Rejection
MHz
15
BW
MOD
I and Q Signal 3dB Bandwidth
mV
p-p
65
V
IF_OUT/IF_OUT
IF Differential Output Voltage
dBc
-60
IM3
IF
IF Output IM3 Level
dBc
-60
IM5
IF
IF Output IM5 Level
UNITS
MIN
TYP
MAX
SYMBOL
PARAMETER
AC ELECTRICAL CHARACTERISTICS (continued)
(MAX2450 EV kit, V
CC
= LO_V
CC
= ENABLE = 3.0V, f
LO
= 140MHz, f
I_IN/I_IN
= f
Q_IN/Q_IN
= 600kHz, V
I_IN/I_IN
= V
Q_IN/Q_IN
= 1.2Vp-p,
f
IF_IN
= 70.1MHz, V
IF_IN
= 2.82mVp-p, T
A
= +25°C, unless otherwise noted.)
MODULATOR
Note 1:
Guaranteed by design, not tested.
Note 2:
f
IF_IN
= 2 tones at 70.10MHz and 70.11MHz. V
IF_IN
= 1.41mVp-p per tone.
Note 3:
The frequency range can be extended in either direction, but has not been characterized. At higher frequencies, the
modulator IF output amplitude may decrease and distortions may increase.
Note 4:
Q_IN/Q_IN ports are terminated. f
I_IN/I_IN
= 2 tones at 550kHz and 600kHz.
__________________________________________Typical Operating Characteristics
(MAX2450 EV kit, V
CC
= LO_V
CC
= ENABLE = 3.0V, f
LO
= 140MHz, f
I_IN/I_IN
= f
Q_IN/Q_IN
= 600kHz, V
I_IN/I_IN
= V
Q_IN/Q_IN
= 1.2Vp-p,
f
IF_IN
= 70.1MHz, V
IF_IN
= 2.82mVp-p, T
A
= +25°C, unless otherwise noted.)
MAX2450
3V, Ultra-Low-Power Quadrature
Modulator/Demodulator
4
_______________________________________________________________________________________
____________________________Typical Operating Characteristics (continued)
(MAX2450 EV kit, V
CC
= LO_V
CC
= ENABLE = 3.0V, f
LO
= 140MHz, f
I_IN/I_IN
= f
Q_IN/Q_IN
= 600kHz, V
I_IN/I_IN
= V
Q_IN/Q_IN
= 1.2Vp-p,
f
IF_IN
= 70.1MHz, V
IF_IN
= 2.82mVp-p, T
A
= +25°C, unless otherwise noted.)
60
62
64
66
68
70
MODULATOR IF OUTPUT
vs. SUPPLY VOLTAGE
MAX2450-04
V
CC
(V)
IF OUTPUT (mVp-p)
3.3
3.2
3.1
3.0
2.9
2.8
2.7
T
A
= +70°C
T
A
= +25°C
T
A
= 0°C
60
62
64
66
68
70
MODULATOR IF OUTPUT
vs.TEMPERATURE
MAX2450-05
TEMPERATURE (°C)
IF OUTPUT (mVp-p)
0
20
40
60
80
V
CC
= 3V
-44
-42
-40
-38
-36
-34
-32
-30
MODULATOR SIDEBAND REJECTION
vs. IF FREQUENCY
MAX2450-06
IF FREQUENCY (MHz)
SIDEBAND REJECTION (dBc)
35
40
70
65
60
55
50
45
75
80
V
I_IN/I_IN
= 1.2Vp-p
V
Q_IN/Q_IN
= 1.2Vp-p
-44
-42
-40
-38
-36
MODULATOR SIDEBAND REJECTION
vs. TEMPERATURE
MAX2450-07
TEMPERATURE (°C)
SIDEBAND REJECTION (dBc)
0
20
40
60
80
V
I_IN/I_IN
= 1.2Vp-p
V
Q_IN/Q_IN
= 1.2Vp-p
-44
-42
-40
-38
-36
-34
-32
-30
CARRIER SUPPRESSION
vs. IF FREQUENCY
MAX2450-08
IF FREQUENCY (MHz)
CARRIER SUPPRESSION (dBc)
35
40
70
65
60
55
50
45
75
80
V
I_IN/I_IN
= 1.2Vp-p
V
Q_IN/Q_IN
= 1.2Vp-p
100mV/
div
PRE_OUT WAVEFORM
MAX2450-09
20ns/div
R
L
= 10k
C
L
< 6pF
-60
69.0
70.6
71.0
MODULATOR OUTPUT SPECTRUM
-50
0
MAX2450-10
(MHz)
(dBc)
69.4
70.0
-20
-10
-30
-40
V
I_IN/I_IN
= 1.2Vp-p
V
Q_IN/Q_IN
= 1.2Vp-p
MAX2450
3V, Ultra-Low-Power Quadrature
Modulator/Demodulator
_______________________________________________________________________________________
5
48.0
48.5
49.0
49.5
50.0
50.5
51.0
51.5
DEMODULATOR VOLTAGE CONVERSION
GAIN vs. TEMPERATURE AND SUPPLY
MAX2450-11
GAIN (dBV)
2.6
2.7
2.8
2.9 3.0
3.1
3.2
3.3
3.4
V
CC
(V)
T
A
= +50°C
T
A
= +25°C
T
A
= 0°C
T
A
= +70°C
50.6
50.8
51.0
51.2
51.4
DEMODULATOR VOLTAGE CONVERSION
GAIN vs. IF FREQUENCY
MAX2450-12
IF FREQUENCY (MHz)
GAIN (dBV)
35
40
70
65
60
55
50
45
75
80
51
50
49
48
47
46
45
44
43
42
DEMODULATOR VOLTAGE CONVERSION
GAIN vs. BASEBAND FREQUENCY
MAX2450-13
BASEBAND FREQUENCY (Hz)
GAIN (dBV)
100M
10M
1M
100k
10k
____________________________Typical Operating Characteristics (continued)
(MAX2450 EV kit, V
CC
= LO_V
CC
= ENABLE = 3.0V, f
LO
= 140MHz, f
I_IN/I_IN
= f
Q_IN/Q_IN
= 600kHz, V
I_IN/I_IN
= V
Q_IN/Q_IN
= 1.2Vp-p,
f
IF_IN
= 70.1MHz, V
IF_IN
= 2.82mVp-p, T
A
= +25°C, unless otherwise noted.)
0.4
0.8
0.6
1.0
1.2
1.4
1.6
DEMODULATOR I/Q PHASE
AND AMPLITUDE MISMATCH
vs. TEMPERATURE
MAX2450-15
TEMPERATURE (°C)
MATCHING (DEGREES OR dBV)
0
10
70
60
50
40
30
20
PHASE MATCH
AMPLITUDE MATCH
-65
-60
-55
-50
-45
-40
DEMODULATOR INTERMOD POWER
vs. TEMPERATURE
MAX2450-16
TEMPERATURE (°C)
INTERMODULATION (dBc)
0
10
70
60
50
40
30
20
IM3
IM5
f
OSC
= 140MHz
f
IF1
= 70.1MHz
f
IF2
= 70.11MHz
V
IF_IN
= 2.82mVp-p
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