MAXIM MAX2750AUA+

19-0831; Rev 0; 6/07
2.4GHz Monolithic
Voltage-Controlled Oscillator for Automotive
Features
The MAX2750AUA is a self-contained voltage-controlled
oscillator (VCO) intended for use over the 2370MHz
to 2470MHz frequency range. The IC combines a fully
integrated oscillator and output buffer in a miniature 8-pin
µMAX® package.
♦ Guaranteed Frequency Tuning Range:
2370MHz to 2470MHz
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.
♦ Low-Current Shutdown Mode
The MAX2750AUA operates 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 2µA.
♦ On-Chip Tank Circuit
♦ Internally Matched Output Buffer Amplifier
♦ +2.7V to +5.5V Supply Voltage Range
♦ Miniature 8-Pin µMAX Package
♦ -40°C to +125°C Temperature Range
Ordering Information
PART
TEMP RANGE
MAX2750AUA+ -40°C to +125°C
PINPACKAGE
8 μMAX
PKG
CODE
U8-1
+Denotes a lead-free package.
Pin Configuration appears at end of data sheet.
________________________Applications
Automotive
2.4GHz ISM Band
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Typical Operating Circuit
BYP
GND
TUNE
TUNE
OSCILLATOR
CORE
OUT
OUT TO MIXER/
SYNTHESIZER
GND
VCC1
MAX2750AUA
VCC
SHDN
SHDN
VCC2
BIAS
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1
MAX2750AUA
General Description
MAX2750AUA
2.4GHz Monolithic
Voltage-Controlled Oscillator for Automotive
ABSOLUTE MAXIMUM RATINGS
VCC to GND ..............................................................-0.3V to +6V
TUNE, SHDN, BYP, OUT to GND ...............-0.3V to (VCC + 0.3V)
Continuous Power Dissipation (TA = +70°C)
8-Pin µMAX (derate 5.7mW/°C above TA = +70°C).....457mW
Operating Temperature Range .........................-40°C to +125°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
(VCC = +2.7V to +5.5V, VTUNE = +0.4V to +2.4V, V SHDN ≤ +2V, OUT = connected to 50Ω load, TA = -40°C to +125°C. Typical values
are at VCC = +3.0V, TA = +25°C, unless otherwise noted.) (Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
5.5
V
TA = +25oC
11.3
14.4
TA = -40°C to +125°C
16.0
21.0
Supply Voltage
Supply Current
2.7
Shutdown Supply Current
2
SHDN Input Voltage Low
μA
0.6
SHDN Input Voltage High
mA
2.0
V
V
SHDN Input Current Low
V SHDN 0.6V
-2
+2
μA
SHDN Input Current High
V SHDN 2.0V
-2
+2
μA
TUNE Input Current
0.4 V TUNE 2.4V
20
nA
AC ELECTRICAL CHARACTERISTICS
(MAX2750AUA EV kit, VCC = +2.7V to +5.5V, VTUNE = +0.4V to +2.4V, V SHDN ≤ +2V, OUT = connected to 50Ω load, TA = +25°C.
Typical values are at VCC = +3.0V, unless otherwise noted.) (Note 1)
PARAMETER
Oscillator Guaranteed Frequency
Limits
Phase Noise
Tuning Gain (Note 2)
CONDITIONS
MIN
o
TYP
MAX
UNITS
2470
MHz
o
V TUNE = +0.4V to +2.4V, TA = -40 C to +125 C
(Note1)
2370
f OFFSET = 4MHz
-125
dBc/Hz
dBm/Hz
Noise floor
-151
f OSC = 2370MHz, +3V
140
f OSC = 2470MHz, +3V
90
MHz/V
Output Power
-3
Return Loss
12
dBm
dB
Harmonics
-30
dBc
4
MHz P-P
1.3
MHz/V
Exiting shutdown (Note 3)
8
μs
Entering shutdown (Note 4)
5
μs
Load Pulling
VSWR = 2:1, all phases
Supply Pushing
VCC stepped: +3.3V to +2.8V
Oscillator Turn-On Time
Oscillator Turn-Off Time
Note 1: Minimum and maximum limits are guaranteed by production test at TA = +25°C and TA = +125°C. Minimum and maximum
limits are guaranteed by design and characterization at TA = -40°C.
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.
2
_______________________________________________________________________________________
2.4GHz Monolithic
Voltage-Controlled Oscillator for Automotive
MAX2750AUA toc01
-50
PHASE NOISE (dBc/Hz)
-70
Δ MKR
-30.00dB
Δ = 30dBc
OUTPUT POWER (dBm)
-60
-80
-90
-100
-110
-120
MAX2750AUA toc02
NORMALIZED HARMONIC
OUTPUT SPECTRUM
PHASE NOISE
Δ = 48dBc
-130
-140
-150
0.1
1
ƒO
10
-30
-40
-50
-60
8μs
-70
MAX2750AUA toc04
OUTPUT POWER (dBm)
-20
0
-10
-20
OUTPUT POWER (dBm)
MAX2750AUA toc03
-10
3ƒO
OSCILLATOR TURN-ON TIME
OSCILLATOR TURN-ON TIME
0
2ƒO
FREQUENCY
OFFSET FREQUENCY (MHz)
-30
-40
-50
-60
4μs
-70
-80
-80
-90
-90
-100
-100
0
2
4
6
8
10 12 14 16 18 20
TIME (μs)
0
2
4
6
8
10 12 14 16 18 20
TIME (μs)
_______________________________________________________________________________________
3
MAX2750AUA
Typical Operating Characterstics
(Circuit of Figure 1, VCC = +3.0V, VTUNE = +0.4V to +2.4V, V SHDN ≤ 2V, TA = +25°C, unless otherwise noted.)
2.4GHz Monolithic
Voltage-Controlled Oscillator for Automotive
MAX2750AUA
Pin Description
PIN
NAME
FUNCTION
1
BYP
2
TUNE
Oscillator Frequency Tuning Voltage Input. High-impedance input with a voltage input range of +0.4V
(low frequency) to +2.4V (high frequency).
3
GND
Ground Connection for Oscillator and Biasing. Requires a low-inductance connection to the circuit
board ground plane.
4
SHDN
5
VCC1
Bias and Oscillator DC Supply Voltage Connection. Bypass separately from pin 6 with a 220pF
capacitor to GND for low noise and low spurious content performance from the oscillator.
6
VCC2
Output Buffer DC Supply Voltage Connection. Bypass separately from pin 5 with a 220pF capacitor to
GND for best high frequency performance.
7
OUT
Buffered Oscillator Output. Incorporates an internal DC-blocking capacitor. OUT is internally matched
to 50.
8
GND
Ground Connection for Output Buffer. Requires a low-inductance connection to the circuit board ground
plane.
VCO Bypass. Bypass with a 0.1μF capacitor to GND.
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.
BYP
MAX2750AUA
0.1μF
GND
TUNE
FROM
SYNTHESIZER
OSCILLATOR
CORE
OUT TO MIXER/
SYNTHESIZER
OUT
LOOP FILTER
220pF
VCC1
GND
VCC
SHDN
SHDN
BIAS
VCC2
220pF
Figure 1. Typical Application Circuit
4
_______________________________________________________________________________________
2.4GHz Monolithic
Voltage-Controlled Oscillator for Automotive
Oscillator
The MAX2750AUA VCO is 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.
Layout Issues
Always use controlled impedance lines (microstrip,
coplanar waveguide, etc.) for high-frequency signals.
Always place decoupling capacitors as close as possible to the VCC pins; 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 as
possible to the device. Thermal reliefs on GND pads
are not recommended.
Pin Configuration
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 VCC and GND pins to minimize
load-pulling effects. The amplifier boosts the oscillator
signal to a level suitable for driving most RF mixers.
TOP VIEW
+
BYP 1
8
GND
7
OUT
3
6
VCC2
SHDN 4
5
VCC1
TUNE 2
MAX2750AUA
GND
Applications Information
Tune Input
µMAX
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 to filter the noise present on the
voltage source driving the tuning line.
_______________________________________________________________________________________
5
MAX2750AUA
Detailed Description
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.)
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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.
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© 2007 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.