MAXIM MAX2750, MAX2751, MAX2752 Technical data

General Description

The MAX2750/MAX2751/MAX2752 are self-contained volt­age-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 inte­grated on-chip, greatly simplifying application of the part.
The only required external components are a couple of
supply bypass capacitors. The IC provides direct connec­tion 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 adjust­ed 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 exter­nal LDO regulator for the VCO. The IC also provides a dig­itally controlled shutdown mode to permit implementation
of sophisticated power-supply management. In shutdown,
the supply current is reduced to less than 1µA.

________________________Applications

802.11b DSSS WLAN

802.11 FHSS WLAN
Home RF

2.4GHz Bluetooth ISM Proprietary Radio

Features

♦ 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)

♦ On-Chip Tank Circuit

♦ Internally Matched Output Buffer Amplifier

♦ Low-Current Shutdown Mode

♦ +2.7V to +5.5V Supply Voltage Range

♦ Miniature 8-Pin µMAX Package

MAX2750/MAX2751/MAX2752

2.4GHz Monolithic

Voltage-Controlled Oscillators

________________________________________________________________ Maxim Integrated Products 1

Typical Operating Circuit

19-1825; Rev 0; 10/00

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

Ordering Information

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.

Pin Configuration appears at end of data sheet.

PART TEMP. RANGE PIN-PACKAGE

MAX2750EUA -40°C to +85°C 8 µMAX

MAX2751EUA -40°C to +85°C 8 µMAX

MAX2752EUA -40°C to +85°C 8 µMAX

BYP

TUNE

SHDN

TUNE

GND

SHDN

MAX2750
MAX2751
MAX2752

OSCILLATOR

CORE

BIAS

GND

OUT

V

V

CC1

CC2

OUT TO MIXER/
SYNTHESIZER

V

CC

ABSOLUTE MAXIMUM RATINGS

MAX2750/MAX2751/MAX2752

2.4GHz Monolithic
Voltage-Controlled Oscillators

2 _______________________________________________________________________________________

DC ELECTRICAL CHARACTERISTICS

(VCC= +2.7V to +5.5V, V

TUNE

= +0.4V to +2.4V, V

SHDN

≤ +2V, OUT = connected to 50Ω load, TA= -40°C to +85°C. Typical values

are at V

CC

= +3.0V, TA= +25°C, unless otherwise noted.) (Note 1)

AC ELECTRICAL CHARACTERISTICS

(MAX2750/MAX2751/MAX2752 EV kit, VCC= +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 VCC= +3.0V, 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.

VCCto 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

PARAMETER CONDITIONS MIN TYP MAX UNITS

Supply Voltage 2.7 5.5 V

Supply Current

Shutdown Supply Current 0.2 1 µA

SHDN Input Voltage Low
SHDN Input Voltage High
SHDN Input Current Low
SHDN Input Current High

TUNE Input Current 0.4 ≤ V

MAX2750

MAX2751

MAX2752

V

V

TA = +25oC

T

= -40oC to +85oC

A

TA = +25oC

T

= -40oC to +85oC

A

TA = +25oC

T

= -40oC to +85oC

A

11.3 14.4

14.1 17.0

9.7 12.1

12.7 15.9

10 12.1

12.8 15.2

2.0 V

≤ 0.6V -2 2 µA

SHDN

SHDN

≥ 2.0V

≤ 2.4V 0.02 nA

TUNE

-2 2 µA

0.6 V

mA

Oscillator Guaranteed
Frequency Limits (Note1)

Phase Noise

PARAMETER CONDITIONS MIN TYP MAX UNITS

= +0.4V to +2.4V,

V

TUNE

T

= -40oC to +85oC

A

f

= 4MHz

OFFSET

Noise floor -151 dBm/Hz

MAX2750

Tuning Gain (Note 2)

MAX2751

MAX2752

Output Power -3 dBm

Return Loss 12 dB

Harmonics -30 dBc

MAX2750 2400 2500 MHz

MAX2751 2120 2260 MHz

MAX2752 2025 2165 MHz

-125 dBc/Hz

f

= 2400MHz, +3V

OSC

f

= 2500MHz, +3V

OSC

f

= 2120MHz, +3V

OSC

f

= 2260MHz, +3V

OSC

f

= 2025MHz, +3V

OSC

f

= 2165MHz, +3V

OSC

140

90

175

110

170

105

MHz/V

MAX2750/MAX2751/MAX2752

2.4GHz Monolithic

Voltage-Controlled Oscillators

_______________________________________________________________________________________ 3

Note 1: Specifications are production tested at TA= +25°C. Limits over temperature are guaranteed by design and characterization.
Note 2: Tuning gain is measured at the oscillator’s guaranteed frequency limits.
Note 3: Turn-on time to within 3dB of final output power
Note 4: Turn-off time to output power of -10dBm.

AC ELECTRICAL CHARACTERISTICS (continued)

(MAX2750/MAX2751/MAX2752 EV kit, VCC= +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 VCC= +3.0V, unless otherwise noted.)

Typical Operating Characteristics

(Circuit of Figure 1, VCC= +3.0V, V

TUNE

= +0.4V to +2.4V, V

SHDN

≤ 2V, TA = +25°C, unless otherwise noted.)

PARAMETER CONDITIONS MIN TYP MAX UNITS

Load Pulling VSWR = 2:1, all phases 4 MHzp-p

V

Supply Pushing

stepped: +3.3V to +2.8V

CC

Oscillator Turn-On Time (Note 3) Exiting shutdown 8 µs

Oscillator Turn-Off Time (Note 4) Entering shutdown 5 µs

1.3 MHz/V

MAX2750/MAX2751/MAX2752

SUPPLY CURRENT vs. TEMPERATURE

15

14

13

12

11

10

SUPPLY CURRENT (mA)

9

8

7

-40 0 20-20 40 60 80

MAX2750

MAX2752

MAX2751

TEMPERATURE (°C)

MAX2750/51/52 toc01

MAX2750/MAX2751/MAX2752

SHUTDOWN CURRENT vs. TEMPERATURE

0.5

0.4

0.3

0.2

SHUTDOWN CURRENT (µA)

0.1

0

-40 0-20 20 40 60 80
TEMPERATURE (°C)

1.0

0.8

MAX2750/51/52 toc02

0.6

0.4

TUNE INPUT CURRENT (nA)

0.2

0

-40 0 20-20 40 60 80

MAX2750/MAX2751/MAX2752

TUNING CURRENT vs. TEMPERATURE

TEMPERATURE (°C)

MAX2750/51/52 toc03

MAX2750

VCO TUNING CURVE

2600

TA = -40°C

2500

2400

FREQUENCY (MHz)

2300

2200

0 1.00.5 1.5 2.0 2.5 3.0

TA = +85°C

V

TUNE

TA = +25°C

(V)

MAX2750/51/52 toc04

FREQUENCY (MHz)

MAX2751

VCO TUNING CURVE

2350

TA = -40°C

2250

2150

TA = +85°C

V

TA = +25°C

TUNE

(V)

2050

1950

1850

0 0.5 1.0 1.5 2.0 2.5 3.0

MAX2750/51/52 toc05

FREQUENCY (MHz)

MAX2752

VCO TUNING CURVE

2350

2250

2150

2050

1950

1850

TA = -40°C

TA = +25°C

TA = +85°C

0 0.5 1.0 1.5 2.0 2.5 3.0

V

(V)

TUNE

MAX2750/51/52 toc06

MAX2750/MAX2751/MAX2752

2.4GHz Monolithic
Voltage-Controlled Oscillators

4 _______________________________________________________________________________________

Pin Description

0.1 1 10

PHASE NOISE

MAX2750/51/52 toc07

OFFSET FREQUENCY (MHz)

PHASE NOISE (dBc/Hz)

-150

-130

-140

-110

-120

-90

-100

-80

-60

-70

-50

MAX2750/51/52 toc08

TEMPERATURE (°C)

OUTPUT POWER (dBm)

-5

-4

-3

-2

-40 0-20 20 40

60 80

MAX2751

OUTPUT POWER vs. TEMPERATURE

MAX2750/51/52 toc09

ƒ

O

3ƒ

O

OUTPUT POWER (dBm)

FREQUENCY

∆ = 48dBc

∆ MKR

-30.00dB

∆ = 30dBc

NORMALIZED HARMONIC

OUTPUT SPECTRUM

2ƒ

O

Typical Operating Characteristics (continued)

(Circuit of Figure 1, VCC= +3.0V, V

TUNE

= +0.4V to +2.4V, V

SHDN

≤ 2V, TA = +25°C, unless otherwise noted.)

-100

-80

-90

-60

-70

-40

-50

-30

-10

-20

0

0 4682 101214 1816 20

OSCILLATOR TURN-ON TIME

MAX2750/51/52 toc10

TIME (µs)

OUTPUT POWER (dBm)

8µs

-100

-80

-90

-60

-70

-40

-50

-30

-10

-20

0

0 4682 101214 1816 20

OSCILLATOR TURN-ON TIME

MAX2750/51/52 toc11

TIME (µs)

OUTPUT POWER (dBm)

4µs

PIN NAME FUNCTION

1 BYP VCO Bypass. Bypass with a 0.1µF capacitor to GND.

2 TUNE

3 GND

4 SHDN

5V

6V

7 OUT

8 GND

CC1

CC2

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.

MAX2750/MAX2751/MAX2752

2.4GHz Monolithic

Voltage-Controlled Oscillators

_______________________________________________________________________________________ 5

Detailed Description

Oscillator

The MAX2750/MAX2751/MAX2752 VCOs are imple­mented 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 con­trolled 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 frequen­cy 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.

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 VCCand GND pins to minimize
load-pulling effects. The amplifier boosts the oscillator
signal to a level suitable for driving most RF mixers.

Applications Information

Tune Input

The tuning input is typically connected to the output of
the PLL loop filter. The loop filter provides an appropri­ately 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 intro­duced 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.

Layout Issues

Always use controlled impedance lines (microstrip,
coplanar waveguide, etc.) for high-frequency signals.
Always place decoupling capacitors as close to the
VCCpins as possible; for long VCClines, it may be nec­essary to add additional decoupling capacitors located
further from the device. Always provide a low-induc­tance path to ground, and keep GND vias as close to
the device as possible. Thermal reliefs on GND pads
are not recommended.

Figure 1. Typical Application Circuit

0.1µF

FROM

SYNTHESIZER

LOOP FILTER

SHDN

BYP

TUNE

GND

SHDN

OSCILLATOR

MAX2750
MAX2751
MAX2752

GND

CORE

BIAS

V

V

OUT

CC1

CC2

220pF

220pF

OUT TO MIXER/
SYNTHESIZER

V

CC

MAX2750/MAX2751/MAX2752

2.4GHz Monolithic
Voltage-Controlled Oscillators

Package Information

Pin Configuration

6 _______________________________________________________________________________________

Chip Information

TRANSISTOR COUNT: 176

PROCESS: BiPOLAR

TOP VIEW

BYP

GND

SHDN

1

2

MAX2750
MAX2751

3

MAX2752

4

µMAX

87GND

OUTTUNE

V

6

CC2

5

V

CC1

8LUMAXD.EPS