LMX2604 [NSC]
Triple-band VCO for GSM900/DCS1800/PCS1900; 三频VCO用于GSM900 / DCS1800 / PCS1900
| 型号： | LMX2604 |
| 厂家： | 
National Semiconductor |
| 描述： | Triple-band VCO for GSM900/DCS1800/PCS1900 |
| 文件： | 总14页 (文件大小：268K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
January 2004
LMX2604
Triple-band VCO for GSM900/DCS1800/PCS1900
General Description
Features
n On-chip Triple-band RF VCOs
GSM: 880 MHz to 915 MHz
DCS: 1710 MHz to 1785 MHz
PCS: 1850 MHz to 1910 MHz
n On-chip tank circuit
The LMX2604 is a fully integrated VCO (Voltage-Controlled
Oscillator) IC designed for GSM900/DCS1800/PCS1900
triple-band application. The IC is ideal for use in the trans-
mitter modulation loop by providing extremely small form
factor and low phase noise. The IC has two VCOs, one for
GSM and a second for DCS/PCS. The IC has two separate
buffer amplifiers to drive an external high power amplifier,
one for GSM900 band and the other one for DCS1800/
PCS1900 bands. The IC also has a differential buffer ampli-
fier to drive a mixer for the offset PLL.
n Low phase noise
— -167 dBc/Hz 20 MHz offset in GSM band
— -163 dBc/Hz 20 MHz offset in DCS band
— -162 dBc/Hz 20 MHz offset in PCS band
@
@
@
n High output power
The resonant circuits of the VCOs are fully integrated in the
chip to ease the application of the IC. The high quality factor
of the embedded tank circuit achieves very low phase noise
characteristics at the VCO output. The only required external
components are a couple of supply bypass capacitors and
matching components.
— +6 dBm in GSM mode
— +6 dBm in DCS and PCS mode
n Low current consumption
— 18 mA in GSM mode
— 15 mA in DCS and PCS mode
n +2.6 V to +3.0 V supply voltage
n 0.25 µm RF CMOS process
n Small 20-pin 4x4 LLP package
A control pin for controlling the oscillation frequency is
shared by the two VCOs.
The LMX2604 IC is provided in a 20-pin 4x4 LLP (Leadless
Leadframe package).
Applications
n Transmit VCO for GSM, DCS, and PCS
n Closed loop modulation systems
Functional Block Diagram
20066101
™
FastLock is a trademark of National Semiconductor Corporation.
TRI-STATE® is a registered trademark of National Semiconductor Corporation.
© 2004 National Semiconductor Corporation
DS200661
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Connection Diagram
20-Pin 4x4 LLP (TM) Package
20066102
Pin Descriptions
Pin Number
Name
CE
I/O
I
Description
1
Chip enable input pin. High=enable, Low=disable
Ground pins
2,4,15
GND (Note 1)
MIXout
BSW
—
O
I
3
Mixer output pin (RF output)
5
Band switch input pin. High=DCS/PCS, Low=GSM
Supply voltage pins
11,19
VDD
—
O
O
I
12
GSMout
DCSPCSout
CPin
RF output pin for VCO in GSM band
RF output pin for VCO in DCS and PCS band
Charge pump input pin
13
16
6,7,8,9,10,14,17,18,20
NC
—
No Connection, These pins must be left open
Note 1: The exposed die attach pad is grounded.
Ordering Information
Package
20-Pin LLP
20-Pin LLP
Part Number
LMX2604LQ
LMX2604LQX
Package Marking
LMX2604LQ
Media Transport
NSC Drawing
LQA20A
1000 Unit Tape and Reel
4500 Unit Tape and Reel
LMX2604LQ
LQA20A
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2
Absolute Maximum Ratings (Notes 3, 4, 5)
Parameter
Supply Voltage
Symbol
VDD
Ratings
-0.3 to 3.6
-0.3 to VDD+0.3
10
Unit
V
Input Voltage
VIN
V
Input Current (Note 2)
Storage Temperature Range
IIN
mA
˚C
TSTG
-65 to 150
Note 2: Maximum input current is for a logic pin, not the power pins.
Recommended Operating Conditions
Parameter
Symbol
TA
Condition
Min
-30
2.6
Typical
25
Max
85
Unit
˚C
Ambient Temperature
Supply Voltage (to GND)
VDD=3V
VDD
2.8
3.0
V
Note 3: “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The
guaranteed specifications apply only for the test conditions listed.
<
Note 4: This Device is a high performance RF integrated circuit with an ESD rating 2 kV and is ESD sensitive. Handling and assembly of this device should only
be done at ESD-free workstations.
Note 5: Stresses in excess of the absolute maximum ratings can cause permanent or latent damage to the device. These are absolute stress ratings only.
Functional operation of the device is only implied at these or any other conditions in excess of those given in the operation sections of the data sheet. Exposure to
absolute maximum ratings for extended periods can adversely affect device reliability
Electrical Characteristics
AC Characteristics (VDD=2.8V, TA=25˚C; unless otherwise noted)
Symbol
Parameter
Remarks
Min
880
1710
1850
10
Typ
Max
915
1785
1910
20
Units
GSM Band
MHz
f
Frequency Range
DCS Band
MHz
PCS Band
GSM Band
15
20
Tuning Sensitivity
(Note 6)
KVCO
DCS Band
15
25
MHz/V
PCS Band
20
25
30
GSM Band
4
6
8
Pout
Output Power
dBm
dBm
DCS & PCS Band
GSM Band
4
6
8
-5.5
-4.5
-3.5
-2.5
-120
-136
-152
-167
-112
-130
-146
-163
-110
-129
-145
-162
-1.5
-0.5
Output power of
MIXout pin
PMIXout
DCS & PCS Band
at 100 kHz offset
at 400 kHz offset
at 3 MHz offset (Note 7)
at 20 MHz offset (Note 7)
at 100 kHz offset
at 400 kHz offset
at 3 MHz offset (Note 7)
at 20 MHz offset (Note 7)
at 100 kHz offset
at 400 kHz offset
at 3 MHz offset (Note 7)
at 20 MHz offset (Note 7)
-128
-124
Phase Noise
(GSM Band)
L(f)
L(f)
L(f)
dBc/Hz
dBc/Hz
Phase Noise
(DCS Band)
-124
-15
Phase Noise
(PCS Band)
dBc/Hz
dBc
Second Harmonic
Suppression
All Bands at RF output port.
-20
Note 6: Tuning Sensitivty is measured after coarse lock. Minimum and maximum limits are supported by characterization.
Note 7: Supported by characterization
3
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Electrical Characteristics (Continued)
DC Characteristics (VDD=2.8V, TA=25˚C; unless otherwise noted)
Symbol
Parameter
Logical Input High
Voltage
Condition
Min
Typ
Max
Units
VIH
0.8VDD
VDD+0.3
V
Logical Input Low
Voltage
VIL
IIH
IIL
-0.3
-2.5
-2.5
0.2VDD
2.5
V
Logical Input High
Current
µA
Logical Input Low
Current
2.5
µA
pF
Input Capacitance
Supply Current
(Note 8)
5
IDD,GSM
18
21
mA
Supply Current
(Note 8)
IDD,DCS/PCS
Istd
15
18
mA
µA
Standby Current
2.5
Note 8: The current consumption in VCO and driver amplifier is all included
Note 9: For CE, BSW, and CPin pins
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4
Typical Performance Characteristics : Phase Noise
Typical phase noise characteristics in GSM band
20066161
Typical phase noise characteristics in DCS band
20066162
5
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Typical Performance Characteristics : Phase Noise (Continued)
Typical phase noise characteristics in PCS band
20066163
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6
Typical Performance Characteristic : GSMout Impedance
GSMout
20066130
GSMout
Frequency (MHz)
Real (Ohms)
Imaginary (Ohms)
Absolute (Ohms)
800
850
900
950
1000
126
126
126
126
125
-72
-74
-75
-77
-80
146
146
146
147
149
7
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Typical Performance Characteristic : MIXout Impedance, GSM
MIXout, GSM
20066131
MIXout, GSM
Frequency (MHz)
Real (Ohms)
Imaginary (Ohms)
Absolute (Ohms)
800
850
900
950
1000
141
133
126
120
115
-256
-249
-243
-237
-232
292
282
274
266
259
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8
Typical Performance Characteristic : DCSPCSout Impedance
DCSPCSout
20066132
DCSPCSout
Frequency (MHz)
1600
Real (Ohms)
Imaginary (Ohms)
Absolute (Ohms)
80
78
77
76
73
71
68
64
57
-54
-53
-51
-50
-49
-48
-48
-48
-51
96
94
93
91
88
85
83
80
77
1650
1700
1750
1800
1850
1900
1950
2000
9
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Typical Performance Characteristic : MIXout Impedance, DCS/PCS
MIXout, DCS/PCS
20066133
MIXout, DCSPCS
Frequency (MHz)
1600
Real (Ohms)
Imaginary (Ohms)
Absolute (Ohms)
66
65
64
66
64
63
62
61
59
-164
-162
-160
-157
-157
-153
-150
-146
-143
177
175
172
171
169
166
162
159
155
1650
1700
1750
1800
1850
1900
1950
2000
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10
FREQUENCY SELECTION AND POWER DOWN
CONTROL
Functional Description
The BSW pin selects the operating frequency band. The
table below shows the appropriate settings with the CE pin.
PRODUCT DESCRIPTION
The LMX2604 IC has two VCOs, which are configured as an
LC resonant oscillator. The active components and tank
elements are all integrated on the IC. The oscillator core and
the tank circuit are designed to be immune to external noise
such as supply and load variation. The IC is easy-to-use and
occupies extremely small area in the board.
CE
BSW
Low
High
Low
High
Output
Low
Low
High
High
X
X
Low Band (GSM)
High Band (DCS/PCS)
Two output amplifiers are also integrated to deliver high
output power of +6 dBm in GSM/DCS/PCS applications. The
amplifiers isolate the oscillator cores from the external load,
and drive the external 50 ohm load. The output driver is
designed to have low noise floor and to reduce pulling by
load variation. An additional amplifier to drive the mixer in the
transmit PLL is also provided. Only an attenuator composed
of a few passive elements is necessary to meet the power
level of the mixer input of the transmit PLL.
In real implementation, the component values of the tank
circuit vary from the nominal value. The IC has built-in circuit
to track the variation and compensate that kind of the varia-
tion during normal operation. This self-correction algorithm
does not require any external control signal and elements.
The figure below shows an application circuit of the
LMX2604. The LMX2604 is developed for the use in a GSM
handset as part of the transmitter PLL. To complete the
offset PLL in the transmit path, several passive elements for
the external loop filter should be also provided. The charge
pump output port of the external transceiver IC is fed to the
CPin pin.
The frequency of the oscillator is controlled by the CPin pin,
which is internally connected to the varactor. This control pin
is connected to the loop filter of the modulation loop in the
transmit path. Any additional noise on this tuning input is
directly translated into FM noise, which can degrade the
phase noise characteristics of the oscillator. Typically, the
loop filter of the PLL provides an appropriately low imped-
ance source at its output and thus proper additional filtering
stage is often required to reduce the high frequency noise
and spurious signals.
The locking process of the LMX2604 is composed of two
stages. First, the internal control circuitry of the LMX2604
controls the fast frequency acquisition behavior of the
LMX2604. After the frequency acquisition, the whole loop
enters in its normal operating mode.
Application Circuit of LMX2604
20066172
11
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frequency such that the final tuning voltage on the CPin line
of the VCO is approximately Vdd/2. Benefits of this system is
the maximum required charge pump voltage is reduced as
large frequency ranges may be tuned with a small tuning
voltage. This makes the digitally tuned VCO different from
conventional analog VCOs.
Functional Description (Continued)
FREQUENCY ACQUISITION
On the rising edge of CE the VCO goes through a frequency
acquisition mode which coarse locks the PLL to the approxi-
mate final frequency. This portion of the lock digitally sets the
Frequency Acquisition Timing Diagram
20066122
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12
Physical Dimensions inches (millimeters) unless otherwise noted
20066107
20-Pin LLP (Leadless Leadframe package) Package
Order Number LMX2604LQX for 4500 Unit Reel
Order Number LMX2604LQ for 1000 Unit Reel
NS Package Number LQA20
13
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