19-1248; Rev 2; 2/02
IT
TION K
VALUA
E
BLE
AVAILA
10MHz to 1050MHz Integrated
RF Oscillator with Buffered Outputs
____________________________Features
♦
Low-Phase-Noise Oscillator: -110dBc/Hz
(25kHz offset from carrier) Attainable
♦
Operates from Single +2.7V to +5.25V Supply
♦
Low-Cost Silicon Bipolar Design
♦
Two Output Buffers Provide Load Isolation
♦
Insensitive to Supply Variations
♦
Low, 27mW Power Consumption (V
CC
= 3.0V)
♦
Low-Current Shutdown Mode: 0.1µA (typ)
_________________General Description
The MAX2620 combines a low-noise oscillator with two
output buffers in a low-cost, plastic surface-mount,
ultra-small µMAX package. This device integrates func-
tions typically achieved with discrete components. The
oscillator exhibits low-phase noise when properly
mated with an external varactor-tuned resonant tank
circuit. Two buffered outputs are provided for driving
mixers or prescalers. The buffers provide load isolation
to the oscillator and prevent frequency pulling due to
load-impedance changes. Power consumption is typi-
cally just 27mW in operating mode (V
CC
= 3.0V), and
drops to less than 0.3µW in standby mode. The MAX2620
operates from a single +2.7V to +5.25V supply.
MAX2620
________________________Applications
Analog Cellular Phones
Digital Cellular Phones
900MHz Cordless Phones
900MHz ISM-Band Applications
Land Mobile Radio
Narrowband PCS (NPCS)
_______________Ordering Information
PART
MAX2620EUA
MAX2620E/D
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 µMAX
Dice*
*Dice
are tested at T
A
= +25°C, DC parameters only.
Pin Configuration appears at end of data sheet.
____________________________________________________Typical Operating Circuit
V
CC
10Ω
1000pF
10nH
1000pF
C17
1.5pF
V
TUNE
1kΩ
D1
ALPHA
SMV1204-34
CERAMIC
RESONATOR
L1
C6
C4
1pF
4 SHDN
BIAS
SUPPLY
C3
2.7pF
C5
1.5pF
1 V
CC
1
OUT 8
1.5pF
V
CC
MAX2620
2 TANK
3 FDBK
V
CC
2 7
GND
6
0.1µF
OUT TO MIXER
V
CC
OUT 5
1000pF
OUT TO SYNTHESIZER
51Ω
SHDN
1000pF
V
CC
900MHz BAND OSCILLATOR
________________________________________________________________
Maxim Integrated Products
1
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.
10MHz to 1050MHz Integrated
RF Oscillator with Buffered Outputs
MAX2620
ABSOLUTE MAXIMUM RATINGS
V
CC
1, V
CC
2 to GND .................................................-0.3V to +6V
TANK,
SHDN
to GND .................................-0.3V to (V
CC
+ 0.3V)
OUT,
OUT
to GND...........................(V
CC
- 0.6V) to (V
CC
+ 0.3V)
FDBK to GND ..................................(V
CC
- 2.0V) to (V
CC
+ 0.3V)
Continuous Power Dissipation (T
A
= +70°C)
µMAX (derate 5.7mW/°C above +70°C) .....................457mW
Operating Temperature Range
MAX2620EUA .................................................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +165°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
1, V
CC
2 = +2.7V to +5.25V, FDBK = open, TANK = open, OUT and
OUT
connected to V
CC
through 50Ω,
SHDN
= 2V,
T
A
= -40°C to +85°C, unless otherwise noted. Typical values measured at V
CC
1 = V
CC
2 = 3.0V, T
A
= +25°C.) (Note 1)
PARAMETER
Supply Current
Shutdown Current
Shutdown Input Voltage High
Shutdown Input Voltage Low
Shutdown Bias Current High
Shutdown Bias Current Low
SHDN
= 2.0V
SHDN
= 0.6V
5.5
SHDN
= 0.6V
2.0
0.6
20
0.5
CONDITIONS
MIN
TYP
9.0
0.1
MAX
12.5
2
UNITS
mA
µA
V
V
µA
µA
Note 1:
Specifications are production tested and guaranteed at T
A
= +25°C and T
A
= +85°C. Specifications are guaranteed by
design and characterization at T
A
= -40°C.
AC ELECTRICAL CHARACTERISTICS
(Test Circuit of Figure 1, V
CC
= +3.0V,
SHDN
= V
CC
, Z
LOAD
= Z
SOURCE
= 50Ω, P
IN
= -20dBm (50Ω), f
TEST
= 900MHz,
T
A
= +25°C, unless otherwise noted.)
PARAMETER
Frequency Range
Reverse Isolation
Output Isolation
CONDITIONS
T
A
= -40°C to +85°C (Note 2)
OUT or
OUT
to TANK; OUT,
OUT
driven at P = -20dBm
OUT to
OUT
MIN
10
50
33
TYP
MAX
1050
UNITS
MHz
dB
dB
Note 2:
Guaranteed by design and characterization at 10MHz, 650MHz, 900MHz, and 1050MHz. Over this frequency range, the
magnitude of the negative real impedance measured at TANK is greater than one-tenth the magnitude of the reactive
impedances at TANK. This implies proper oscillator start-up when using an external resonator tank circuit with Q > 10. C3
and C4 must be tuned for operation at the desired frequency.
2
_______________________________________________________________________________________
10MHz to 1050MHz Integrated
RF Oscillator with Buffered Outputs
TYPICAL OPERATING CIRCUIT PERFORMANCE—900MHz Band Ceramic-
Resonator-Based Tank
(Typical
Operating Circuit,
V
CC
= +3.0V, V
TUNE
= 1.5V,
SHDN
= V
CC,
load at OUT = 50Ω, load at
OUT
= 50Ω, L1 = coaxial ceramic
resonator: Trans-Tech SR8800LPQ1357BY, C6 = 1pF, T
A
= +25°C, unless otherwise noted.)
PARAMETER
Tuning Range
Phase Noise
V
TUNE
= 0.5V to 3.0V
SSB at
∆f
= 25kHz
SSB at
∆f
= 300kHz
At OUT (Note 2)
Output Power (Single-Ended)
At OUT, per test circuit of Figure 1; T
A
= -40°C to +85°C
(Note 3)
At
OUT
(Note 3)
Noise Power
Average Tuning Gain
Second-Harmonic Output
Load Pull
Supply Pushing
VSWR = 1.75:1, all phases
V
CC
stepped from 3V to 4V
f
O
± >10MHz
-6
-11
-16
CONDITIONS
MIN
TYP
±13
-110
-132
-2
-8
-12.5
-147
11
-29
163
71
dBm/Hz
MHz/V
dBc
kHz
P-P
kHz/V
dBm
MAX
UNITS
MHz
dBc/Hz
MAX2620
Note 3:
Guaranteed by design and characterization.
TYPICAL OPERATING CIRCUIT PERFORMANCE—900MHz Band Inductor-Based Tank
(Typical
Operating Circuit,
V
CC
= +3.0V, V
TUNE
= 1.5V,
SHDN
= V
CC,
load at OUT = 50Ω, load at
OUT
= 50Ω, L1 = 5nH (Coilcraft
A02T), C6 = 1.5pF, T
A
= +25°C, unless otherwise noted.)
PARAMETER
Tuning Range
Phase Noise
V
TUNE
= 0.5V to 3.0V
SSB at
∆f
= 25kHz
SSB at
∆f
= 300kHz
At OUT (Note 2)
Output Power (single-ended)
At OUT, per test circuit of Figure 1; T
A
= -40°C to +85°C
(Note 3)
At
OUT
(Note 3)
Noise Power
Average Tuning Gain
Second-Harmonic Output
Load Pull
Supply Pushing
VSWR = 1.75:1, all phase angles
V
CC
stepped from 3V to 4V
f
O
± >10MHz
-6
-11
-16
CONDITIONS
MIN
TYP
±15
-107
-127
-2
-8
-12.5
-147
13
-29
340
150
dBm/Hz
MHz/V
dBc
kHz
P-P
kHz/V
dBm
MAX
UNITS
MHz
dBc/Hz
Note 3:
Guaranteed by design and characterization.
_______________________________________________________________________________________
3
10MHz to 1050MHz Integrated
RF Oscillator with Buffered Outputs
MAX2620
__________________________________________Typical Operating Characteristics
(Test Circuit of Figure 1, V
CC
= +3.0V,
SHDN
= V
CC
, Z
LOAD
= Z
SOURCE
= 50Ω, P
IN
= -20dBm/50Ω, f
TEST
= 900MHz, T
A
= +25°C,
unless otherwise noted.)
OUT OUTPUT POWER vs. FREQUENCY
OVER V
CC
AND TEMPERATURE
-5
V
CC
= 5.25V
-6
POWER (dBm)
C
V
CC
= 5.25V
MAX2620-01
OUT OUTPUT POWER vs. FREQUENCY
OVER V
CC
AND TEMPERATURE
-11.0
T
A
= +85°C
T
A
= +25°C
T
A
= -40°C
POWER (dBm)
V
CC
= 5.25V
-11.5
T
A
= +25°C
-12.0
T
A
= -40°C
-12.5
V
CC
= 2.7V
-13.0
MAX2620-02
T
A
= +85°C
-7
V
CC
= 2.7V
A
B
V
CC
= 2.7V
-8
-9
0
200
400
600
800
1000
1200
FREQUENCY (MHz)
A: 10MHz BAND CIRCUIT
B: NOT CHARACTERIZED FOR THIS FREQUENCY BAND.
EXPECTED PERFORMANCE SHOWN.
C: 900MHz BAND CIRCUIT
-13.5
0
200
400
600
800
1000
1200
FREQUENCY (MHz)
Table 1. Recommended Load Impedance at OUT or
OUT
for
Optimum Power Transfer
FREQUENCY
(MHz)
250
350
450
550
650
750
850
950
1050
REAL COMPONENT
(R in
Ω)
106
68
60
35
17.5
17.2
10.9
7.3
6.5
IMAGINARY COMPONENT
(X in
Ω)
163
102
96
79
62.3
50.6
33.1
26.3
22.7
4
_______________________________________________________________________________________
10MHz to 1050MHz Integrated
RF Oscillator with Buffered Outputs
MAX2620
_____________________________Typical Operating Characteristics (continued)
(Typical
Operating Circuit,
V
CC
= +3.0V, V
TUNE
= 1.5V,
SHDN
= V
CC,
load at OUT = 50Ω, load at
OUT
= 50Ω, L1 = coaxial ceramic
resonator: Trans-Tech SR8800LPQ1357BY, C6 = 1pF, T
A
= +25°C, unless otherwise noted.)
900MHz BAND CIRCUIT*
TYPICAL 1/S11 vs. FREQUENCY
MEASURED AT TEST PORT
MAX2620-04
REVERSE ISOLATION vs. FREQUENCY
0
REVERSE ISOLATION (dB)
-10
-20
-30
-40
-50
-60
-70
-80
-90
50
250
450
650
850
1050
FREQUENCY (MHz)
V
CC
= 2.7V TO 5.25V
C3, C4 REMOVED
MAX2620-03
1050MHz
21 + j78
900MHz
36 + j90
800MHz
49 + j105
650MHz
84 + j142
*SEE FIGURE 1
MAX2620-05
9.5
15MHz
28 + j79.8
10MHz
63.6 + j121.5
5MHz
262 + j261
SUPPLY CURRENT (mA)
V
CC
= 5.25V
9.0
V
CC
= 2.7V
8.5
8.0
7.5
7.0
-40
C3 = C4 = 270pF
L3 = 10µH
C2 = C10 = C13 = 0.01µF
-20
0
20
40
60
80
100
TEMPERATURE (°C)
_______________________________________________________________________________________
MAX2620-06
10MHz BAND CIRCUIT
TYPICAL 1/S11 vs. FREQUENCY
MEASURED AT TEST PORT
SUPPLY CURRENT
vs. TEMPERATURE
10.0
5
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