19-1825; Rev 0; 10/00
L
MANUA
ION KIT HEET
AT
EVALU
TA S
WS DA
FOLLO
2.4GHz Monolithic
Voltage-Controlled Oscillators
Features
o
Guaranteed Frequency Tuning Range
MAX2750: 2400MHz to 2500MHz (Zero IF)
MAX2751: 2120MHz to 2260MHz
(240MHz to 280MHz IF)
MAX2752: 2025MHz to 2165MHz
(335MHz to 375MHz IF)
o
On-Chip Tank Circuit
o
Internally Matched Output Buffer Amplifier
o
Low-Current Shutdown Mode
o
+2.7V to +5.5V Supply Voltage Range
o
Miniature 8-Pin µMAX Package
General Description
The MAX2750/MAX2751/MAX2752 are self-contained volt-
age-controlled oscillators (VCOs) intended for use in the
2.4GHz to 2.5GHz ISM band. Each IC combines a fully
integrated oscillator and output buffer in a miniature 8-pin
µMAX package.
The inductor and varactor elements of the tank are inte-
grated on-chip, greatly simplifying application of the part.
The only required external components are a couple of
supply bypass capacitors. The IC provides direct connec-
tion to the VCO tuning voltage input and the VCO buffer
output. The tuning voltage input range is +0.4V to +2.4V,
and the oscillator frequency tuning range is factory adjust-
ed to provide guaranteed limits. The output signal is
buffered by an amplifier stage (internally matched to 50Ω)
to provide higher output power and isolate the device from
load impedance variations.
The MAX2750/MAX2751/MAX2752 operate over a +2.7V
to +5.5V supply voltage range. Internal regulation of the
oscillator supply voltage eliminates the need for an exter-
nal LDO regulator for the VCO. The IC also provides a dig-
itally controlled shutdown mode to permit implementation
of sophisticated power-supply management. In shutdown,
the supply current is reduced to less than 1µA.
MAX2750/MAX2751/MAX2752
Ordering Information
PART
MAX2750EUA
MAX2751EUA
MAX2752EUA
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 µMAX
8 µMAX
8 µMAX
________________________Applications
802.11b DSSS WLAN
802.11 FHSS WLAN
Home RF
2.4GHz Bluetooth ISM Proprietary Radio
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
BYP
GND
TUNE
TUNE
OSCILLATOR
CORE
OUT
OUT TO MIXER/
SYNTHESIZER
GND
V
CC1
SHDN
SHDN
MAX2750
MAX2751
MAX2752
BIAS
V
CC
V
CC2
________________________________________________________________
Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
2.4GHz Monolithic
Voltage-Controlled Oscillators
MAX2750/MAX2751/MAX2752
ABSOLUTE MAXIMUM RATINGS
V
CC
to GND ..............................................................-0.3V to +6V
TUNE,
SHDN,
BYP, OUT to GND ...............-0.3V to (V
CC
+ 0.3V)
Continuous Power Dissipation (T
A
= +70°C)
8-Pin µMAX (derate 5.7mW/°C above T
A
= +70°C).....457mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
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.
DC ELECTRICAL CHARACTERISTICS
(V
CC
= +2.7V to +5.5V, V
TUNE
= +0.4V to +2.4V, V
SHDN
≤
+2V, OUT = connected to 50Ω load, T
A
= -40°C to +85°C. Typical values
are at V
CC
= +3.0V, T
A
= +25°C, unless otherwise noted.) (Note 1)
PARAMETER
Supply Voltage
MAX2750
Supply Current
MAX2751
MAX2752
Shutdown Supply Current
SHDN
Input Voltage Low
SHDN
Input Voltage High
SHDN
Input Current Low
SHDN
Input Current High
TUNE Input Current
V
SHDN
≤
0.6V
V
SHDN
≥
2.0V
0.4
≤
V
TUNE
≤
2.4V
2.0
-2
-2
0.02
2
2
T
A
= +25 C
T
A
= -40 C to +85 C
T
A
= +25 C
T
A
= -40 C to +85 C
T
A
= +25
o
C
T
A
= -40 C to +85 C
o
o
o
o
o
o
o
o
CONDITIONS
MIN
2.7
TYP
11.3
14.1
9.7
12.7
10
12.8
0.2
MAX
5.5
14.4
17.0
12.1
15.9
12.1
15.2
1
0.6
UNITS
V
mA
µA
V
V
µA
µA
nA
AC ELECTRICAL CHARACTERISTICS
(MAX2750/MAX2751/MAX2752 EV kit, V
CC
= +2.7V to +5.5V, V
TUNE
= +0.4V to +2.4V, V
SHDN
≤
+2V, OUT = connected to 50Ω load,
T
A
= +25°C. Typical values are at V
CC
= +3.0V, unless otherwise noted.)
PARAMETER
Oscillator Guaranteed
Frequency Limits (Note1)
CONDITIONS
MAX2750
V
TUNE
= +0.4V to +2.4V,
T
A
= -40
o
C to +85
o
C
f
OFFSET
= 4MHz
Noise floor
MAX2750
Tuning Gain (Note 2)
MAX2751
MAX2752
Output Power
Return Loss
Harmonics
f
OSC
= 2400MHz, +3V
f
OSC
= 2500MHz, +3V
f
OSC
= 2120MHz, +3V
f
OSC
= 2260MHz, +3V
f
OSC
= 2025MHz, +3V
f
OSC
= 2165MHz, +3V
MAX2751
MAX2752
Phase Noise
MIN
2400
2120
2025
-125
-151
140
90
175
110
170
105
-3
12
-30
dBm
dB
dBc
MHz/V
TYP
MAX
2500
2260
2165
UNITS
MHz
MHz
MHz
dBc/Hz
dBm/Hz
2
_______________________________________________________________________________________
2.4GHz Monolithic
Voltage-Controlled Oscillators
MAX2750/MAX2751/MAX2752
AC ELECTRICAL CHARACTERISTICS (continued)
(MAX2750/MAX2751/MAX2752 EV kit, V
CC
= +2.7V to +5.5V, V
TUNE
= +0.4V to +2.4V, V
SHDN
≤
+2V, OUT = connected to 50Ω load,
T
A
= +25°C. Typical values are at V
CC
= +3.0V, unless otherwise noted.)
PARAMETER
Load Pulling
Supply Pushing
Oscillator Turn-On Time (Note 3)
Oscillator Turn-Off Time (Note 4)
CONDITIONS
VSWR = 2:1, all phases
V
CC
stepped: +3.3V to +2.8V
Exiting shutdown
Entering shutdown
MIN
TYP
4
1.3
8
5
MAX
UNITS
MHzp-p
MHz/V
µs
µs
Note 1:
Note 2:
Note 3:
Note 4:
Specifications are production tested at T
A
= +25°C. Limits over temperature are guaranteed by design and characterization.
Tuning gain is measured at the oscillator’s guaranteed frequency limits.
Turn-on time to within 3dB of final output power
Turn-off time to output power of -10dBm.
Typical Operating Characteristics
(Circuit of Figure 1, V
CC
= +3.0V, V
TUNE
= +0.4V to +2.4V, V
SHDN
≤
2V, T
A
= +25°C, unless otherwise noted.)
MAX2750/MAX2751/MAX2752
SUPPLY CURRENT vs. TEMPERATURE
MAX2750/51/52 toc01
MAX2750/MAX2751/MAX2752
SHUTDOWN CURRENT vs. TEMPERATURE
MAX2750/51/52 toc02
MAX2750/MAX2751/MAX2752
TUNING CURRENT vs. TEMPERATURE
MAX2750/51/52 toc03
15
14
SUPPLY CURRENT (mA)
13
12
11
10
9
8
7
-40
-20
0
20
40
TEMPERATURE (°C)
60
80
MAX2752
MAX2751
MAX2750
0.5
1.0
SHUTDOWN CURRENT (µA)
TUNE INPUT CURRENT (nA)
0.4
0.8
0.3
0.6
0.2
0.4
0.1
0.2
0
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
0
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
MAX2750
VCO TUNING CURVE
MAX2750/51/52 toc04
MAX2751
VCO TUNING CURVE
MAX2750/51/52 toc05
MAX2752
VCO TUNING CURVE
2350
2250
T
A
= -40°C
2150
2050
1950
1850
MAX2750/51/52 toc06
2600
2350
2250
2150
T
A
= +25°C
2050
1950
T
A
= +85°C
T
A
= -40°C
2500
FREQUENCY (MHz)
T
A
= -40°C
FREQUENCY (MHz)
2400
T
A
= +25°C
FREQUENCY (MHz)
2300
T
A
= +85°C
T
A
= +25°C
T
A
= +85°C
2200
0
0.5
1.0
1.5
V
TUNE
(V)
2.0
2.5
3.0
1850
0
0.5
1.0
1.5
V
TUNE
(V)
2.0
2.5
3.0
0
0.5
1.0
1.5
V
TUNE
(V)
2.0
2.5
3.0
_______________________________________________________________________________________
3
2.4GHz Monolithic
Voltage-Controlled Oscillators
MAX2750/MAX2751/MAX2752
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
CC
= +3.0V, V
TUNE
= +0.4V to +2.4V, V
SHDN
≤
2V, T
A
= +25°C, unless otherwise noted.)
PHASE NOISE
MAX2750/51/52 toc07
MAX2751
OUTPUT POWER vs. TEMPERATURE
MAX2750/51/52 toc08
NORMALIZED HARMONIC
OUTPUT SPECTRUM
∆
MKR
-30.00dB
OUTPUT POWER (dBm)
MAX2750/51/52 toc09
-50
-60
-70
PHASE NOISE (dBc/Hz)
-80
-90
-100
-110
-120
-130
-140
-150
0.1
1
OFFSET FREQUENCY (MHz)
-2
∆
= 30dBc
∆
= 48dBc
OUTPUT POWER (dBm)
-3
-4
-5
10
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
0
-10
-20
OUTPUT POWER (dBm)
-30
-40
-50
-60
-70
-80
-90
-100
0
2
4
6
8
10 12 14 16 18 20
0
2
4
6
8
4µs
ƒ
O
2ƒ
O
FREQUENCY
3ƒ
O
OSCILLATOR TURN-ON TIME
-10
-20
OUTPUT POWER (dBm)
-30
-40
-50
-60
-70
-80
-90
-100
TIME (µs)
8µs
MAX2750/51/52 toc10
OSCILLATOR TURN-ON TIME
MAX2750/51/52 toc11
0
10 12 14 16 18 20
TIME (µs)
Pin Description
FUNCTION
PIN
1
2
3
4
5
6
7
8
NAME
BYP
TUNE
GND
SHDN
V
CC1
V
CC2
OUT
GND
VCO Bypass. Bypass with a 0.1µF capacitor to GND.
Oscillator Frequency Tuning Voltage Input. High-impedance input with a voltage input range of +0.4V
(low frequency) to +2.4V (high frequency).
Ground Connection for Oscillator and Biasing. Requires a low-inductance connection to the circuit
board ground plane.
Shutdown Logic Input. A high-impedance input logic level low disables the device and reduces
supply current to less than 1.0µA. A logic level high enables the device.
Bias and Oscillator DC Supply Voltage Connection. Bypass separately from PIN6 with a 220pF
capacitor to GND for low noise and low spurious content performance from the oscillator.
Output Buffer DC Supply Voltage Connection. Bypass separately from PIN5 with a 220pF capacitor to
GND for best high frequency performance.
Buffered Oscillator Output. Incorporates an internal DC blocking capacitor. OUT is internally matched
to 50Ω.
Ground Connection for Output Buffer. Requires a low-inductance connection to the circuit board
ground plane.
4
_______________________________________________________________________________________
2.4GHz Monolithic
Voltage-Controlled Oscillators
MAX2750/MAX2751/MAX2752
BYP
0.1µF
MAX2750
MAX2751
MAX2752
GND
FROM
SYNTHESIZER
LOOP FILTER
TUNE
OSCILLATOR
CORE
OUT
OUT TO MIXER/
SYNTHESIZER
220pF
V
CC1
GND
V
CC
SHDN
SHDN
BIAS
V
CC2
220pF
Figure 1. Typical Application Circuit
Detailed Description
Oscillator
The MAX2750/MAX2751/MAX2752 VCOs are imple-
mented as an LC oscillator topology, integrating all of
the tank components on-chip. This fully monolithic
approach provides an extremely easy-to-use VCO,
equivalent to a VCO module. The frequency is con-
trolled by a voltage applied to the TUNE pin, which is
internally connected to the varactor. The VCO core
uses a differential topology to provide a stable frequen-
cy versus supply voltage and improve the immunity to
load variations. In addition, there is a buffer amplifier
following the oscillator core to provide added isolation
from load variations and to boost the output power.
Applications Information
Tune Input
The tuning input is typically connected to the output of
the PLL loop filter. The loop filter provides an appropri-
ately low-impedance source. The input may incorporate
an extra RC filter stage to reduce high-frequency noise
and spurious signals. Any excess noise on the tuning
input is directly translated into FM noise, which can
degrade the phase-noise performance of the oscillator.
Therefore, it is important to minimize the noise intro-
duced on the tuning input. A simple RC filter with low
corner frequency is needed during testing in order to
filter the noise present on the voltage source driving the
tuning line.
Output Buffer
The oscillator signal from the core drives an output
buffer amplifier. The amplifier is internally matched to
50Ω including an on-chip DC blocking capacitor. No
external DC blocking capacitor is required, eliminating
the need for any external components. The output
amplifier has its own V
CC
and GND pins to minimize
load-pulling effects. The amplifier boosts the oscillator
signal to a level suitable for driving most RF mixers.
Layout Issues
Always use controlled impedance lines (microstrip,
coplanar waveguide, etc.) for high-frequency signals.
Always place decoupling capacitors as close to the
V
CC
pins as possible; for long V
CC
lines, it may be nec-
essary to add additional decoupling capacitors located
further from the device. Always provide a low-induc-
tance path to ground, and keep GND vias as close to
the device as possible. Thermal reliefs on GND pads
are not recommended.
_______________________________________________________________________________________
5
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