MAXIM MAX2754

19-2102; Rev 1; 8/03
KIT
ATION
EVALU
E
L
B
A
IL
AVA
1.2GHz VCO with Linear
Modulation Input
Features
♦ Fully Monolithic VCO Construction with On-Chip
Inductor and Varactor Tuning Elements
♦ Guaranteed 1145MHz to 1250MHz Tuning Range
to Support 1/2 LO Applications
♦ Modulation Linearity Within ±4%
♦ Precise Modulation Gain (-500kHz/V)
♦ Low Phase Noise (-137dBc/Hz at 4MHz offset)
♦ +2.7V to +5.5V Single-Supply Operation
♦ Low-Current Shutdown Mode
♦ Miniature 8-Pin µMAX Package
Ordering Information
PART
MAX2754EUA
TEMP RANGE
PIN-PACKAGE
-40°C to +85°C
8 µMAX
8-pin µMAX
(3mm ✕ 5mm)
Typical Operating Circuit
Applications
HomeRF WLAN
Bluetooth
VCC
VREG
2.4GHz Cordless Phones
2.4GHz Wireless Data Radios
REG AND BIAS
VCC
330nF
330nF
Pin Configuration
TUNE
TUNE
OSCILLATOR
CORE
OUT
OUT TO
MIXER/
SYNTHESIZER
TOP VIEW
GND2
GND1
VREG
1
TUNE
2
GND1
3
MOD
4
8
MAX2754
µMAX
VCC
7
OUT
6
GND2
5
SHDN
MODULATION
VOLTAGE
SIGNAL
LINEAR
MODULATION
INTERFACE
MOD
SHDN
SHDN
MAX2754
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
MAX2754
General Description
The MAX2754 self-contained, linear modulation, voltage-controlled oscillator (VCO) is intended for use in
the 2.4GHz to 2.5GHz ISM band, particularly for FSK
modulation systems that utilize a direct frequency-modulation transmit architecture. This device features a linear modulation input in addition to the standard
frequency tuning input. The frequency tuning range of
1145MHz to 1250MHz (1/2 LO) also supports an IF up
to 110MHz with low side LO. The VCO is based on
Maxim’s proprietary monolithic VCO technology, where
all VCO components are integrated on-chip, including
the varactor and inductor.
The MAX2754 linear modulation input offers a means to
directly FM modulate the VCO with a constant modulation sensitivity over the tuning voltage input range.
Typical frequency deviation is -500kHz/V which is linear
to ±4% over the guaranteed frequency limits. The tuning input voltage range is +0.4V to +2.4V and the oscillator frequency is factory adjusted to provide
guaranteed limits. The oscillator signal is buffered by
an output amplifier stage (internally matched to 50Ω) to
provide higher output power and isolate the oscillator
from load impedance variations.
The MAX2754 operates over a +2.7V to +5.5V supply
range. This device also provides a digitally controlled
shutdown mode to permit implementation of sophisticated power-supply management. In shutdown, the
supply current is reduced to 0.2µA. Even when active,
power consumption is a modest 41mW.
The MAX2754 is packaged in the miniature 8-pin µMAX
to offer the world’s smallest, complete 2.4GHz directmodulation VCO solution.
MAX2754
1.2GHz VCO with Linear
Modulation Input
ABSOLUTE MAXIMUM RATINGS
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10s) .................................+300°C
VCC to GND ...........................................................-0.3V to +6.0V
VREG to GND ........................................................-0.3V to +6.0V
TUNE, SHDN, MOD to GND.......................-0.3V to (VCC + 0.3V)
OUT to GND ..........................................................-0.3V to +6.0V
Continuous Power Dissipation (TA = +70°C)
8-Pin µMAX (derate 5.7mW/°C above TA = +70°C) ....457mW
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.
CAUTION! ESD SENSITIVE DEVICE
DC ELECTRICAL CHARACTERISTICS
(VCC = +2.7V to +5.5V, VTUNE = +0.4V to +2.4V, V SHDN ≥ +2.0V, VMOD = +1.4V, OUT is connected to a 50Ω load, TA = -40°C to
+85°C. Typical values are at VCC = +3.0V, TA = +25°C, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
Supply Voltage
VCC
Supply Current
ICC
CONDITIONS
MIN
TA = +25°C, V SHDN ≥ 2.0V
Digital Input Voltage High
VIH
Digital Input Voltage Low
VIL
Digital Input Current High
IIH
V SHDN ≥ 2.0V
IIL
V SHDN ≤ 0.6V
Modulation Input Voltage Range
MAX
UNITS
5.5
V
16.4
20
-2
0.2
mA
2
µA
0.6
V
2
µA
-1
1
µA
0.4
2.4
2.0
V
-2
VMOD
TUNE Leakage Current (Note 2)
13.7
TA = -40°C to +85°C, V SHDN ≥ 2.0V
V SHDN ≤ 0.6V
Digital Input Current Low
TYP
2.7
VTUNE = +0.4V to +2.4V
0.01
V
nA
AC ELECTRICAL CHARACTERISTICS
(MAX2754 EV kit. VCC = +2.7V to +5.5V, VTUNE = +0.4V to +2.4V, V SHDN ≥ +2.0V, VMOD = +1.4V, OUT is connected to a 50Ω load,
TA = +25°C. Typical values are at VCC = +3.0V, TA = +25°C, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
Oscillator Guaranteed Frequency
Limits
fMIN,
fMAX
Phase Noise
Tuning Gain
CONDITIONS
VTUNE = +0.4V to +2.4V,
TA = -40°C to +85°C
MIN
1145
MAX
UNITS
1250
MHz
fOFFSET = 4MHz
-137
dBc/Hz
Noise floor
-151
dBm/Hz
VTUNE at fMIN
124
VTUNE at fMAX
81
Output Power
MHz/V
-5
Modulation Peak Frequency
Deviation
fMIN < f < fMAX (Note 2)
Modulation Sensitivity
Common-mode VMOD = 1.4V
2
TYP
±400
±500
-500
_______________________________________________________________________________________
dBm
±600
kHz
kHz/V
1.2GHz VCO with Linear
Modulation Input
(MAX2754 EV kit. VCC = +2.7V to +5.5V, VTUNE = +0.4V to +2.4V, V SHDN ≥ +2.0V, VMOD = +1.4V, OUT is connected to a 50Ω load,
TA = +25°C. Typical values are at VCC = +3.0V, TA = +25°C, unless otherwise noted.) (Note 1)
PARAMETER
Modulation Linearity
SYMBOL
CONDITIONS
VMOD = +0.4 to +2.4V,
fMIN < f < fMAX (Note 4)
Modulation Full-Power Bandwidth
(Note 5)
Return Loss (Note 6)
fMIN < f < fMAX
Output Harmonics
MIN
TYP
MAX
UNITS
±4
%
2.5
MHz
7.5
dB
-20
dBc
Load Pulling
VSWR = 2:1, all phases
1.5
MHzp-p
Supply Pushing
VCC stepped: +3.3V to +2.8V
0.16
MHz/V
Oscillator Turn-On Time (Note 7)
10
µs
Oscillator Turn-Off Time (Note 8)
8
µs
Specifications are production tested at TA = +25°C. Limits over temperature are guaranteed by design and characterization.
Limits are guaranteed by production test at +25°C.
Center point is nominally +1.4V.
Maximum variation in the modulation sensitivity from its average value over the guaranteed frequency limits.
Bandwidth is defined as the point where the response to the modulation port is 0.707 times the low-frequency response.
Bandwidth limits on the modulation input for a 1Vp-p sine wave. Common-mode VMOD = +1.4V.
Note 6: Refer to Output Buffer section for suggestions to improve the return loss to 12dB.
Note 7: Turn-on time to within 3dB of final output power.
Note 8: Turn-off time to output power of -10dBm.
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
_______________________________________________________________________________________
3
MAX2754
AC ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(MAX2754 EV kit, VCC = +3.0V, V SHDN ≥ +2.0V, VTUNE = VMOD = +1.4V, and TA = +25°C, unless otherwise noted.)
VCO TUNING CURVE
1050
TA = +85°C
1000
-480
-500
-520
-540
-560
950
0
0.5
1.0
1.5
2.0
2.5
3.0
1140
1160
1180
MAX2754 toc04
OUTPUT POWER (dBm)
OUTPUT POWER (dBm)
-4.0
-4.5
VCC = +4.0V
-5.0
VCC = +2.7V
-5.5
1200
1220
1240
0.4
0.2
1260
-40
-15
10
35
60
TEMPERATURE (°C)
OUTPUT POWER
vs. FREQUENCY
NORMALIZED HARMONIC
OUTPUT SPECTRUM
-2
TA = +85°C
-3
VCC = +5.5V
0.6
CARRIER FREQUENCY (MHz)
OUTPUT POWER vs. FREQUENCY
-3.5
0.8
0
-600
VTUNE (V)
-3.0
TA = +25°C
TA = +85°C
-580
MAX2754 toc03
MAX2754 toc02
TA = -40°C
-460
85
MAX2754 toc06
1100
-440
1.0
TUNING INPUT CURRENT (nA)
TA = +25°C
1150
-420
∆ = -20dBc
OUTPUT POWER (dBm)
1200
TUNE INPUT CURRENT
vs. TEMPERATURE
MAX2754 toc05
TA = -40°C
1250
-400
MODULATION SENSITIVITY (kHz/V)
1300
FREQUENCY (MHz)
MODULATION SENSITIVITY vs.
CARRIER FREQUENCY
MAX2754 toc01
1350
-4
-5
TA = +25°C
-6
∆ = -30dBc
TA = -40°C
-7
-6.0
1160
1180
1200
1220
1240
1260
-8
1140
FREQUENCY (MHz)
1160
1180
1200
1220
1240
ƒO
1260
OSCILLATOR TURN-ON/
TURN-OFF TIME
-10
-90
-100
-110
-120
-130
SHDN LOW-TO-HIGH
AT TIME = 0
-20
OUTPUT POWER (dBm)
-80
-30
-5
-40
-50
SHDN HIGH-TO-LOW
AT TIME = 0
-60
-70
-150
-90
-160
-100
10
100
1000
OFFSET FREQUENCY (kHz)
10,000
-10
-15
-80
-140
3ƒO
OUTPUT S11
0
S11 (dB)
-70
4
0
MAX2754 toc07
-60
MAX2754 toc08
PHASE NOISE
2ƒO
FREQUENCY
FREQUENCY (MHz)
MAX2754 toc09
1140
PHASE NOISE (dBc/Hz)
MAX2754
1.2GHz VCO with Linear
Modulation Input
-20
0
10
20
30
TIME (µs)
40
50
800 900 1000 1100 1200 1300 1400 1500 1600
FREQUENCY (MHz)
_______________________________________________________________________________________
1.2GHz VCO with Linear
Modulation Input
PIN
NAME
FUNCTION
1
VREG
Capacitor Connection to the On-Chip Linear Regulator Output. Connect a 330nF capacitor to ground.
2
TUNE
Oscillator Frequency Tuning-Voltage Input. High-impedance input with a voltage range of +0.4V (low
frequency) to +2.4V (high frequency).
3
GND1
Ground Connection for the Oscillator Core. Requires a low-inductance connection to the circuitboard ground plane.
4
MOD
Linear Modulation Input. High-impedance CMOS input with a voltage range of +0.4V to +2.4V.
5
SHDN
Shutdown Input. Drive logic low to place the device in shutdown mode. Drive logic high for normal
operation.
6
GND2
Ground Connection for Output-Buffered Amplifier, Linear Modulation Interface, and Biasing.
Requires a low-inductance connection to the circuit-board ground plane.
7
OUT
Buffered Oscillator Output. Incorporates an internal DC-blocking capacitor. OUT is internally
matched to 50Ω.
8
VCC
Supply Voltage Connection. Requires external RF bypass capacitor to ground for low noise and low
spurious content performance from the oscillator. Bypass with a 330pF capacitor to ground.
Detailed Description
Oscillator
The MAX2754 VCO is implemented as an LC oscillator
topology, integrating all of the tank components onchip. 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. 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 and supply
variations and to boost the output power.
Linear Modulation
The linear modulation input offers a means to directly
FM modulate the VCO with a controlled amount of frequency deviation for a given input voltage deviation.
The unique technique maintains a consistent modulation gain (df/dVMOD) across the entire frequency tuning
range of the part, enabling accurate FM modulation
derived solely from the filtered NRZ “data” stream (the
modulation voltage input).
The modulation input is single-ended and centered
about +1.4V. The linear modulation full-scale range is
±1V around this point, for a +0.4V to +2.4V input voltage range. A very important point to note is that the
sign of the modulation gain is negative. A positive
change in VMOD results in a negative change in oscilla-
tion frequency. This convention for the modulation gain
is due to the practical implementation of the internal linearizing circuitry. This gain inversion must be considered when designing the analog voltage interface that
drives the linear modulation input. The easiest way to
handle this is to invert the logic polarity of the modulation data three-state output buffer (TX data output).
Where it is impossible to invert the data-stream logic
polarity, an external inverter and three-state buffer
would be required. These devices are offered in small
single-logic gates in SC-79 style packages from various
manufacturers (e.g., Fairchild—Tiny Logic, On
Semiconductor, or Rohm).
Figure 1 illustrates the frequency versus VMOD characteristic of the modulation input. Note the negative slope
of the curve, dfMOD/dVMOD < 0, where fMOD = fOUT fNOM.
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. The
return loss can be improved to a minimum of 12dB over
1145MHz to 1250MHz by adding a 2.5nH series inductor and a 3.0pF shunt capacitor. The output buffer has
a ground connection separate from the oscillator core
to minimize load-pulling effects. The amplifier boosts
the oscillator signal to a level suitable for driving most
RF mixers.
_______________________________________________________________________________________
5
MAX2754
Pin Description
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. 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 to filter the
noise present on the voltage source driving the tuning
line.
fNOM + fMOD
OUTPUT FREQUENCY (MHz)
MAX2754
1.2GHz VCO with Linear
Modulation Input
fNOM
fNOM - fMOD
0.5
Two-Level FSK Applications
The MAX2754 is designed for use in FSK applications
operating in the 2.4GHz to 2.5GHz ISM band. Specifically,
it is targeted for those systems which utilize a direct TX
modulation architecture in which the VCO is directly modulated with the data signal during the transmit (TX) mode.
The VCO in these systems runs at half the RF output
frequency and is used in conjunction with a frequency
doubler to produce the final LO signal for both RX and
TX modes of operation.
1.0
1.5
2.0
Figure 1. Modulation Frequency Deviations Characteristics
Figure 2 shows a typical applications circuit. To compute R1, R2, R3, and R4, determine the modulation
voltage center point (VMODB = +1.4V). Compute the
required modulation voltage deviation as follows:
VCC
VREG
REG AND BIAS
VCC
330nF
330nF
VCC
FROM PLL
LOOP FILTER
TUNE
OSCILLATOR
CORE
OUT
OUT TO
MIXER/
SYNTHESIZER
R1
INVERTED
CMOS
SIGNAL
R2
GND1
R3
MOD.
FILTER
R4
GND2
LINEAR
MODULATION
INTERFACE
MOD
SHDN
FROM BASEBAND
DIGITAL
CONTROLLER
MAX2754
Figure 2. Typical Application Circuit for Two-Level FSK
6
2.5
MODULATION VOLTAGE, VMOD (V)
_______________________________________________________________________________________
1.2GHz VCO with Linear
Modulation Input
Let R = R1 + R3 + R4. Setting R based on the desired
current from VCC and filter impedance level:
R1 =
R
,
2
V

R
R2 =  MODB − 1 × ,
∆
4
V


1

V
R 3 = R ×  − MODB  ,
VCC 
2
R4 =
VMODB
VCC
Layout Issues
Use controlled impedance lines (microstrip, co-planar
waveguide, etc.) each time for high-frequency signals.
Always place decoupling capacitors as close to the
VCC pins as possible; for long VCC lines, 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.
Chip Information
TRANSISTOR COUNT: 619
× R
_______________________________________________________________________________________
7
MAX2754
∆V = ∆f / 500kHz/V (nominal modulation sensitivity)
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
4X S
8
8
INCHES
DIM
A
A1
A2
b
E
ÿ 0.50±0.1
H
c
D
e
E
H
0.6±0.1
L
1
1
α
0.6±0.1
S
BOTTOM VIEW
D
MIN
0.002
0.030
MAX
0.043
0.006
0.037
0.014
0.010
0.007
0.005
0.120
0.116
0.0256 BSC
0.120
0.116
0.198
0.188
0.026
0.016
6∞
0∞
0.0207 BSC
8LUMAXD.EPS
MAX2754
1.2GHz VCO with Linear
Modulation Input
MILLIMETERS
MAX
MIN
0.05
0.75
1.10
0.15
0.95
0.25
0.36
0.13
0.18
2.95
3.05
0.65 BSC
2.95
3.05
4.78
5.03
0.41
0.66
0∞
6∞
0.5250 BSC
TOP VIEW
A1
A2
A
α
c
e
b
L
SIDE VIEW
FRONT VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
APPROVAL
DOCUMENT CONTROL NO.
21-0036
REV.
J
1
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2003 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.