NSC LMX5080MX

April 1999
LMX5080
PLLatinum™ 2.7 GHz Low Power Dual Modulus
Prescaler for RF Personal Communications
General Description
Features
The LMX5080 integrated dual modulus prescaler, is designed to be used in a synthesized local oscillator for
2.5 GHz wireless transceivers. It is fabricated using National’s 0.5µ ABiCV silicon BiCMOS process. The LMX5080 contains three dual modulus prescalers. Either a 128/130,
256/158 or a 512/514 prescaler can be selected for up to
2.7 Gz RF input frequencies. The prescaler inputs can be
driven either differentially, or single ended with the use of a
coupling capacitor on one of the inputs to ground. The
LMX5080 CMOS output is optimized to generate very stable,
low switching noise output signals. The LMX5080 prescaler
can be used in conjunction with a low frequency Phase Lock
Loop to form a frequency synthesizer suitable for UHF transceivers. Supply voltage can range from 2.7V to 5.5V. The
LMX5080 features low current consumption; typically 7.0 mA
at 5V VCC
n
n
n
n
2.7V to 5.5V operation
Low current consumption: 7 mA (typ) @ 5V
−40˚C to +85˚C low noise CMOS output
Selectable dual modulus prescaler
128/130
256/258
512/514
n 8-pin small package outline (SOP)
Applications
n 2.5 GHz wireless communications systems (ISM)
n Direct Broadcast Satellite systems (DBS)
n Cable TV tuners (CATV)
The LMX5080 is available in a 8-pin Small Outline (SOP)
surface mount plastic package.
Functional Block Diagram
DS100940-1
PLLatinum™ is a trademark of National Semiconductor Corporation.
© 1999 National Semiconductor Corporation
DS100940
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LMX5080 PLLatinum 2.7 GHz Low Power Dual Modulus Prescaler for RF Personal
Communications
PRELIMINARY
Connection Diagram
Small Outline Package (SOP)
DS100940-2
NS Package Number M08A
Order Number LMX5080M, LMX5080MX
Pin Descriptions
Pin
No.
Pin
Name
I/O
Description
1
IN
I
RF small signal prescaler input. Small signal input from the voltage controlled
oscillator
2
VCC
—
Power Supply voltage input may range from 2.7V to 5.5V. Bypass capacitors
should be placed as close as possible to this pin and be connected directly
to the ground plane.
3
SW1
I
Divide Ratio Control. CMOS logic input. Pin functionality is described in the
Modulus Control Truth Table.
4
OUT
O
Prescaler Output. CMOS level output for connection to low frequency PLL
input.
5
GND
—
6
MC
I
Modulus Control Input. High impedance CMOS logic input. Pin functionality is
described in the Modulus Control Truth Table.
7
SW2
I
Divide Ratio Control. High impedance CMOS logic input. Pin functionality is
described in the Modulus Control Truth Table.
8
IN
I
RF small signal prescaler complementary input. In single-ended mode, a
bypass capacitor should be placed as close as possible to this pin and be
connected directly to the ground plane. The IN and IN can be driven
differentially when the bypass capacitor is omitted.
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Ground for analog and digital signals.
2
Absolute Maximum Ratings (Note 1)
Recommended Operating
Conditions (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Value
Parameter
Value
Parameter
Symbol
Min
VCC
−0.3
Power Supply
Voltage
Typ
Symbol
Min
Max
Units
Power Supply
Voltage
VCC
6.5
V
Operating
Temperature
TA
Voltage on any
pin with
GND = 0V
Vi
−0.3
VCC+0.3
V
Storage
Temperature
Range
TS
−65
+1.50
˚C
Lead Temp.
(solder 4 sec)
TL
+2.60
˚C
Typ
Max
Units
2.7
5.5
V
−40
+85
˚C
Note 1: “Absolute Maximum Ratings” indicate limits beyond which damage
to the device may occur. Recommended Operating Conditions indicate conditions for which the device is intended to be functional, but do not guarantee
specific performance limits. Electrical Characteristics document specific minimum and/or maximum performance values at specified test conditions and
are guaranteed. Typ or Typical values are for informational purposes only
which are based on design parameters or device characterization and are not
guaranteed.
Note 2: This device is a high performance RF integrated circuit and is ESD
sensitive. Handling and assembly of this device should only be done on ESDfree workstations.
Electrical Characteristics
(VCC = 5.0V, TA = −40˚C to +85˚C except as specified) (Note 1)
Symbol
Parameter
ICC
Power Supply Current
VOH
Output Amplitude
VOL
fin
Input Frequency
Condition
Value
Min
Typ
Max
7
ZL = 100 kΩ//10 pF
VCC = 2.7V to 5.5V
AC coupled. VCC = 2.7V to 5.5V
VCC = 2.7V to 5.5V
Units
mA
0.9 x VCC
V
0.1 x VCC
V
100
2700
MHz
−15
+4
dBm
0.1
25
MHz
Pfin
Operational Input Signal Amplitude
fout
Output Frequency
VIH
High-level Input Voltage (MC, SW1,
SW2)
VIL
Low-level Input Voltage (MC, SW1,
SW2)
IIH
High-level Input Current (MC, SW1,
SW2)
VIH = 0.7 x VCC
±1
uA
IIL
Low-level Input Current (MC, SW1,
SW2)
VIL = 0.3 x VCC
±1
uA
tSet
Modulus Control Set-up time. (Note 3)
SW1 = H, SW2 = H
fin = 2.7 GHz
15
20
ns
IM
Input/Output Intermodulation (Note 4)
−10 dBm / 50Ω AC coupled
signal delivered to input.
VCC = 2.7V to 5.5V.
MC = 0, MC = 1.
Fin = 2.3 GHz to 2.5 GHz.
−35
−30
dBc
0.7 x VCC
V
0.3 x VCC
V
Note 3: See Timing Diagram.
Note 4: Guaranteed by design and characterization, not tested. Output frequency measured at input.
3
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Functional Description
the low frequency synthesizer, or a controller to set the prescaler divide ratio to N or N+2. The prescaler output frequency is established by dividing the VCO signal down via
the prescaler modulus. The RF inputs to the prescalar consist of the Fin and /Fin input pins which are complementary
inputs to a differential pair amplifier. This configuration can
operate to 2 GHz with an input sensitivity of −15 dBm.
The basic phase-lock-loop (PLL) configuration using an external prescaler consists of a high-stability crystal reference
oscillator, a prescaler such as the National Semiconductor
LMX5080, a low frequency synthesizer, a voltage controlled
oscillator (VCO), and a loop filter. The frequency synthesizer
typically includes programmable reference [R] and feedback
[N] frequency dividers, a phase detector, as well as a charge
pump. The MC signal is fed back to the prescaler from either
Block Diagram
DS100940-3
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4
Modulus Control Truth Table
SW1
SW2
MC
Divide Ratio
H
H
H
1/128
H
H
L
1/130
H
L
H
1/256
L
H
H
1/256
H
L
L
1/258
L
H
L
1/258
L
L
H
1/512
L
L
L
1/514
Note: SW1, SW2, MC: H = 0.7 x VCC, L = 0.3 x VCC.
Timing Diagram
DS100940-4
5
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Typical Performance Characteristics
ICC vs VCC
N = 1/128, TA = 25˚C
RF Input Sensitivity vs Frequency
DS100940-6
DS100940-7
Input Impedance (S11) vs Frequency
VCC = 2.7V to 5.5V, fin = 100 MHz to 2.7 GHz
DS100940-8
Marker
Marker
Marker
Marker
1
2
3
4
=
=
=
=
100 MHz, Real = 364, Imag = −253
1 GHz, Real = 104, Imag = −136
2 GHz, Real = 26, Imag = −53
2.7 GHz, Real = 36, Imag = −23
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6
inches (millimeters) unless otherwise noted
8 Lead (0.150” Wide) Molded Small Outline Package, JEDEC
Order Number LMX5080M
For Tape and Reel
Order Number LMX5080MX
NS Package Number M08A
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL
SEMICONDUCTOR CORPORATION. As used herein:
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systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.
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LMX5080 PLLatinum 2.7 GHz Low Power Dual Modulus Prescaler for RF Personal
Communications
Physical Dimensions