NSC LMX3162VBH

March 2000
LMX3162
Single Chip Radio Transceiver
General Description
The LMX3162 Single Chip Radio Transceiver is a monolithic,
integrated radio transceiver optimized for use in ISM 2.45
GHz wireless systems. It is fabricated using National’s ABiC
V BiCMOS process (fT = 18 GHz).
The LMX3162 contains phase locked loop (PLL), transmit
and receive functions. The 1.3 GHz PLL is shared between
transmit and receive sections. The transmitter includes a frequency doubler, and a high frequency buffer. The receiver
consists of a 2.5 GHz low noise mixer, an intermediate frequency (IF) amplifier, a high gain limiting amplifier, a frequency discriminator, a received signal strength indicator
(RSSI), and an analog DC compensation loop. The PLL,
doubler, and buffers can be used to implement open loop
modulation along with an external VCO and loop filter. The
circuit features on-chip voltage regulation to allow supply
voltages ranging from 3.0V to 5.5V. Two additional voltage
regulators provide a stable supply source to external discrete stages in the Tx and Rx chains.
The IF amplifier, high gain limiting amplifier, and discriminator are optimized for 110 MHz operation, with a total IF gain
of 85 dB. The single conversion receiver architecture provides a low cost, high performance solution for communications systems. The RSSI output may be used for channel
quality monitoring.
The Single Chip Radio Transceiver is available in a 48-pin
7mm X 7mm X 1.4mm PQFP surface mount plastic package.
Features
n Single chip solution for ISM 2.45 GHz RF transceiver
n System RF sensitivity to −93 dBm; RSSI sensitivity to
−100 dBm
n Two regulated voltage outputs for discrete amplifiers
n High gain (85 dB) intermediate frequency strip
n Allows unregulated 3.0V–5.5V supply voltage
n Power down mode for increased current savings
n System noise figure 6.5 dB (typ)
Applications
n
n
n
n
ISM 2.45 GHz frequency band wireless systems
Personal wireless communications (PCS/PCN)
Wireless local area networks (WLANs)
Other wireless communications systems
Block Diagram
DS100929-1
MICROWIRE™ is a trademark of National Semiconductor Corporation.
TRI-STATE ® is a registered trademark of National Semiconductor Corporation.
© 2000 National Semiconductor Corporation
DS100929
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LMX3162 Single Chip Radio Transceiver
PRELIMINARY
LMX3162
LMX3162 Connection Diagram
DS100929-2
Top View
Order Number LMX3162VBH or LMX3162VBHX
See NS Package Number VBH48A
Pin Descriptions
Pin No.
Pin Name
I/O
1
VCC
—
Power supply for CMOS section of PLL and
ESD bussing.
2
MIXEROUT
O
IF output from the mixer.
3
VCC
—
Power supply for mixer section.
4
GND
—
5
RFIN
I
6
GND
—
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Description
Ground.
RF input to the mixer.
Ground.
2
LMX3162
Pin Descriptions
(Continued)
Pin No.
Pin Name
I/O
7
Tx VREG
—
Regulated power supply for external PA gain
stage.
Description
8
VCC
—
Power supply for analog sections of PLL and
doubler.
9
GND
—
Ground.
10
TxOUT
O
Frequency doubler output.
11
GND
—
Ground.
12
VCC
—
Power supply for analog sections of PLL and
doubler.
13
GND
—
Ground.
14
GND
—
Ground.
15
fIN
I
RF Input to PLL and frequency doubler.
16
CE
I
Chip Enable. Pulling LOW powers down entire
chip. Taking CE HIGH powers up the
appropriate functional blocks depending on the
state of bits F6, F7, F11, and F12 programmed
in F-latch. It is necessary to initialize the internal
registers once, after the power up reset. The
registers’ contents are kept even in power-down
condition.
17
VP
—
Power supply for charge pump.
18
Do
O
Charge pump output. For connection to a loop
filter for driving the input of an external VCO.
19
VCC
—
Power supply for CMOS section of PLL and
ESD bussing.
20
GND
—
Ground.
3
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LMX3162
Pin Descriptions
(Continued)
Pin No.
Pin Name
I/O
Description
21
OUT 0
O
Programmable CMOS output. Refer to Function
Register Programming Description section for
details.
22
Rx PD/OUT 1
I/O
Receiver power down control input or
programmable CMOS output. Refer to Function
Register Programming Description section for
details.
23
Tx PD/OUT 2
I/O
Transmitter power down control input or
programmable CMOS output. Refer to Function
Register Programming Description section for
details.
24
PLL PD
I
PLL power down control input. LOW for PLL
normal operations, and HIGH for PLL power
saving.
25
CLOCK
I
MICROWIRE™ clock input. High impedance
CMOS input with Schmitt Trigger.
26
DATA
I
MICROWIRE data input. High impedance
CMOS input with Schmitt Trigger.
27
LE
I
MICROWIRE load enable input. High
impedance CMOS input with Schmitt Trigger.
28
OSCIN
I
Oscillator input. High impedance CMOS input
with feedback.
29
S FIELD
I
DC compensation circuit enable. While LOW,
the DC compensation circuit is enabled and the
threshold is updated through the DC
compensation loop. While HIGH, the switch is
opened, and the comparator threshold is held
by the external capacitor.
30
RSSIOUT
O
Received signal strength indicator (RSSI)
output.
31
THRESH
O
Threshold level to external comparator.
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LMX3162
Pin Descriptions
(Continued)
Pin No.
Pin Name
I/O
32
DC COMPIN
I
Input to DC compensation circuit.
Description
33
DISCOUT
O
Demodulated output of discriminator.
34
GND
—
Ground.
35
VCC
—
36
QUADIN
I
Power supply for the discriminator circuit.
Quadrature input for tank circuit.
37
VCC
—
Power supply for limiter output stage.
38
GND
—
Ground.
39
VCC
—
Power supply for limiter gain stages.
40
GND
—
Ground.
41
VCC
—
Power supply for IF amplifier gain stages.
42
LIMIN
I
43
GND
—
Ground.
44
IFOUT
O
IF output from IF amplifier.
45
VCC
—
Power supply for IF amplifier output.
46
GND
—
Ground.
IF input to the limiter.
5
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LMX3162
Pin Descriptions
(Continued)
Pin No.
Pin Name
I/O
47
IFIN
I
48
Rx VREG
—
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Description
IF input to IF amplifier.
Regulated power supply for external LNA
stages.
6
Power Supply Voltage (VCC)
VP
Voltage on Any Pin with
GND = 0V (VI)
Storage Temperature Range (TS)
Lead Temp. (solder, 4 sec)(TL)
LMX3162
Absolute Maximum Ratings (Notes 1, 2)
Recommended Operating
Conditions
−0.3V to +6.5V
−0.3V to +6.5V
Supply Voltage (VCC)
(VP)
Operating Temperature (TA)
−0.3V to VCC +0.3V
−65˚C to +150˚C
+260˚C
3.0V to 5.5V
VCC to 5.5V
−10˚C to +70˚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. For guaranteed specifications and test conditions, see the Electrical Characteristics section. The guaranteed specifications apply only for the test conditions listed.
Note 2: This device is a high performance RF integrated circuit with an ESD
rating < KeV and is ESD sensitive. Handling and assembly of this device
should only be done at ESD work stations.
Electrical Characteristics
The following specifications are guaranteed for VCC = 3.6V and TA = 25˚C, unless otherwise specified.
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
—
50
65
mA
Current Consumption
ICC, RX
-Open-Loop Receive Mode
ICC, TX
-Open-Loop Transmit Mode
PLL & RX chain powered down
—
27
40
mA
ICC, PLL
-PLL only Mode
RX & TX chain powered down
—
6
9
mA
IPD
-Power Down Mode
—
—
70
µA
MIXER
PLL & TX chain powered down
fRF = 2.45 GHz, fIF = 110 MHz, f
LO
= 2340 MHz (fIN = 1170 MHz)
fRF
RF Frequency Range
(Note 3)
2.4
—
2.5
GHz
fIF
IF Frequency
(Note 4)
—
110
—
MHz
ZIN
Input Impedance, RFIN
—
12+j6
—
Ω
ZOUT
Output Impedance, Mixer Out
—
160−j65
—
Ω
NF
Noise Figure (Single Side Band)
(Notes 5, 6)
—
11.8
16
dB
G
Conversion Gain
(Note 5)
13
17
—
dB
P1dB
Input 1dB Compression Point
(Note 5)
—
−20
—
dBm
OIP3
Output 3rd Order Intercept Point
(Note 5)
—
7.5
—
dBm
FIN-RF
Fin to RF Isolation
FIN =1170 MHz, RFOUT=1170 MHz
—
−30
—
dB
FIN =1170 MHz, RFOUT=2340 MHz
—
−20
—
dB
FIN =1170 MHz, RFOUT=3510 MHz
—
−30
—
dB
FIN =1170 MHz, IFOUT=1170 MHz
—
−30
—
dB
FIN =1170 MHz, IFOUT=2340 MHz
—
−30
—
dB
FIN-IF
RF–IF
Fin to IF Isolation
RF to IF Isolation
IF AMPLIFIER
FIN =1170 MHz, IFOUT=3510 MHz
—
−30
—
dB
PIN =0 to −85 dB
—
−30
—
dB
fIN = 110 MHz
NF
Noise Figure
(Note 7)
—
8
11
dB
AV
Gain
(Note 7)
15
24
—
dB
ZIN
Input Impedance
—
35–j180
—
Ω
ZOUT
Output Impedance
—
210–j50
—
Ω
—
−65
—
dBm
—
100–j300
—
Ω
IF LIMITER
fIN = 110 MHz
Sens
Limiter/Discriminator Sensitivity
BER=10−3 (Note 16)
IFIN
IF Limiter Input Impedance
DISCRIMINATOR
VOUT
VOS
fIN = 110 MHz
Disc Gain
1X Mode
—
10
—
mV/˚
(mV/˚ of Phase Shift from Tank Circuit)
3X Mode
—
33
—
mV/˚
Discriminator Output Peak to Peak
1X Mode (Note 8)
80
160
—
mV
Voltage
3X Mode (Note 8)
400
580
—
mV
Disc. Output DC Voltage
Nominal (Note 10)
1.2
—
1.82
V
—
300
—
Ω
DISCOUT Disc. Output Impedance
7
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LMX3162
Electrical Characteristics
(Continued)
The following specifications are guaranteed for VCC = 3.6V and TA = 25˚C, unless otherwise specified.
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
PIN =−80 dBm@IFIN input pin
0.12
0.2
0.6
V
RSSI (Note 11)
fIN = 110 MHz
RSSIout
RSSI
Output Voltage
PIN =−20 dBm@IFIN input pin
0.9
1.2
—
V
Slope
PIN = −85 to −25 dBm@IFIN input pin
10
18
25
mV/dB
Dynamic Range
PIN min= −90 dBm@IFIN input pin
—
60
—
dB
−6
—
+6
mV
—
1.0
—
VPP
2000
3000
3600
Ω
1100
—
1300
MHz
—
−11.5
—
dBm
DC COMPENSATION CIRCUIT
VOS
Input Offset Voltage
VI/O
Input/Output Voltage Swing
RSH
Sample and Hold Resistor
Centered at 1.5V
FREQUENCY SYNTHESIZER
fIN
Input Frequency Range
(Note 9)
PIN
Input Signal Level
ZIN =200Ω (Note 15)
fOSC
Oscillator Frequency Range
(Note 12)
5
—
20
MHz
VOSC
Oscillator Sensitivity
(Note 12)
0.5
1.0
—
Vpp
IDo-source Charge Pump Output Current
Vdo = V P/2, Icpo = LOW
(Note 14)
—
−1.5
—
mA
IDo-sink
Vdo = V P/2, Icpo = LOW
(Note 14)
—
1.5
—
mA
IDo-source
Vdo = V P/2, Icpo = HIGH
(Note 14)
—
−6.0
—
mA
IDo-sink
Vdo = V P/2, ICPO = HIGH
(Note 14)
—
6.0
—
mA
IDo-Tri
0.5 ≤ Vdo ≤ Vp − 0.5
TA = 25˚C
−1.0
—
1.0
nA
FREQUENCY DOUBLER(Note 17)
fIN = 1225 MHz, fOUT = 2.45 GHz
fOUT
Output Frequency Range
(Note 13)
2250
—
2500
MHz
POUT
Output Signal Level
PIN = −11.5 dBm, fOUT = 2.45 GHz
−12
−7.5
—
dBm
Fundamental Output Power
PIN = −11.5 dBm, fOUT = 1225 MHz
—
−17
−10
dBm
Harmonic Output Power
PIN = −11.5 dBm, fOUT = 3.675 GHz
—
−30
−15.5
dBm
2.55
2.75
2.90
V
VOLTAGE REGULATOR
VO
Output Voltage
ILOAD = 5 mA
DIGITAL INPUT/OUTPUT PINS
VIH
High Level Input Voltage
2.4
—
—
V
VIL
Low Level Input Voltage
—
—
0.8
V
IIH
Input Current
GND < VIN < VCC
−10
—
10
µA
VOH
High Level Output Voltage
IOH =−0.5 mA
2.4
—
—
V
VOL
Low Level Output Voltage
IOL =0.5 mA
—
—
0.4
V
Note 3: The mixer section is tested at 2.45 GHz.
Note 4: The IF section of this device is designed for optimum performance at 110 MHz.
Note 5: The matching network used on RFIN for this measurement consists of a series 3.3 pF capacitance into the pin. The matching circuit used on MIXEROUT consists of a series 150 nH inductance and a shunt 15 pF capacitance into the pin.
Note 6: Noise figure measurements are made with matching networks on RFIN and MIXEROUT. See (Note 5).
Note 7: The matching network used on pin IFIN for this measurement conists of a series 330 nH inductance and a shunt 2.7 pF capacitance into the pin. The matching network used on pin IFOUT consists of a series 120 nH inductance and a shunt 12 pF into the pin..
Note 8: The discriminator is with the DC level centered at 1.5V. The unloaded Q of the tank is 40.
Note 9: The frequency synthesizer section is tested at 1.225 GHz.
Note 10: Nominal refers to zero DC offsets programmed for the discriminator.
Note 11: It depends on loss of the inter-stage filter. These specifications are for an inter-stage loss of 8 dB.
Note 12: The frequency synthesizer section is guaranteed by design to operate for OSCIN input frequency within 5–20 MHz range and minimum amplitude of
0.5 VPP.
Note 13: The doubler section is tested at 2.45 GHz.
Note 14: See Function Register Programming Description for Icpo description.
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LMX3162
Electrical Characteristics
(Continued)
Note 15: Tested in a 50Ω environment.
Note 16: The matching network used on pin LIMIN for this measurement consists of a series 330 nH inductance and a shunt 1.8 pF into the pin.
Note 17: The optimum load as seen by the TX OUT pin should be between 50 and 100 ohms.
Typical Performance Characteristics
Mixer POUT vs
FIN Power with RFIN =
−51 dBm, @ 2450 MHz, 25˚C
Mixer POUT vs
FIN Power with RFIN =
−51 dBm, @ 2450 MHz, VCC =3.6V
DS100929-16
RSSI Output vs
Input Power to IFIN
with VCC as Parameter
DS100929-17
IDO TRI-STATE™ vs
DO Voltage, VCC =5.5V
DS100929-19
DS100929-18
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LMX3162
Typical Performance Characteristics
(Continued)
Charge Pump Current vs
DO Voltage VCC =3.6V, 25˚C
Charge Pump Current vs
DO Voltage, VCC =3.0V, 25˚C
DS100929-20
Mixer OIP3 vs FIN Power
DS100929-21
Mixer Gain vs FIN Power
DS100929-43
Mixer Output Power vs Mixer Input Power
DS100929-44
Mixer Gain vs RFIN Frequency
DS100929-46
DS100929-45
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(Continued)
SSB Mixer Noise Figure vs RFIN Frequency
SSB Mixer Noise Figure vs FIN Power
LMX3162
Typical Performance Characteristics
DS100929-48
DS100929-47
TX Power Out vs FIN Power
TX Power Out vs FIN Frequency
DS100929-49
DS100929-50
AC Timing Characteristics
Serial Data Input Timing
TEST CONDITIONS: The Serial Data Input Timing is tested using a symmetrical waveform around VCC/2. The test waveform has
an skew rate of 0.6 V / ns.
DS100929-3
Notes: Parenthesis data indicates programmable reference divider data.
Data shifted into register on clock rising edge.
Data is shifted in MSB first.
11
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LMX3162
Serial Data Input Timing
Symbol
(Continued)
Parameter
Conditions
Min
Typ
Max
Unit
MICROWIRE™ Interface
tCS
Data to Clock Set Up Time
Refer to Test Condition.
50
—
—
ns
tCH
Data to Clock Hold Time
Refer to Test Condition.
10
—
—
ns
tCWH
Clock Pulse Width High
Refer to Test Condition.
50
—
—
ns
tCWL
Clock Pulse Width Low
Refer to Test Condition.
50
—
—
ns
tES
Clock to Load Enable Set Up Time
Refer to Test Condition.
50
—
—
ns
tEW
Load Enable Pulse Width
Refer to Test Condition.
50
—
—
ns
PLL Functional Description
The simplified block diagram below shows the building blocks of frequency synthesizer and all internal registers, which are 20-bit
data register, 18-bit F-latch, 13-bit N-counter, and 5-bit R-counter.
DS100929-4
The DATA stream is clocked into the data register on the rising edge of CLOCK signal, MSB first. The last two bits are the control
bits to indicate which register to be written. Upon the rising edge of the LE (Load Enable) signal, the rest of data bits is transferred
to the addressed register accordingly. The decoding scheme of the two control bits is as follows:
Control Bits
Register
C2
C1
0
0
N-Counter
1
0
R-Counter
X
1
F-Latch
Note: X = Don’t Care Condition
Programmable Feedback Divider (N-Counter)
The N-counter consists of the 6-bit swallow counter (A-counter) and the 7-bit programmable counter (B-counter). When the control bits are “00”, data is transferred from the 20-bit shift register into two latches. One latch sets the A-counter while the other sets
the B-counter. The serial data format is shown below.
MSB
REGISTER’S BIT MAPPING
19
18
X
X
17
16
15
14
13
12
11
10
X
N13
N12
N11
N10
RESERVED
X
9
8
LSB
7
6
5
4
3
2
N5
N4
N3
N2
N1
N-COUNTER’s Divide Ratio
X
N9
N8
N7
N6
Note: X = Don’t Care Condition
Swallow Counter Divide Ratio (A-Counter)
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Divide Ratio, A
N6
N5
N4
N3
N2
N1
0
0
0
0
0
0
0
1
0
0
0
0
0
1
*
*
*
*
*
*
*
63
1
1
1
1
1
1
12
1
0
C2
C1
0
0
LMX3162
Swallow Counter Divide Ratio (A-Counter)
(Continued)
Note: Divide ratio must be from 0 to 63, and B must be ≥ A.
Programmable Counter Divide Ratio (B-Counter)
Divide Ratio, B
N13
N12
N11
N10
N9
N8
N7
3
0
0
0
0
0
1
1
4
0
0
0
0
1
0
0
*
*
*
*
*
*
*
*
127
1
1
1
1
1
1
1
Note: Divide ratio must be from 3 to 127, and B must be ≥ A.
Programmable Reference Divider (R-Counter)
If the control bits are “10”, data is transferred from the 20-bit shift register into a latch, which sets the 5-bit R-counter. The serial
data format is shown below.
MSB
19
REGISTER’S BIT MAPPING
18
17
16
15
14
13
12
11
10
9
LSB
8
7
RESERVED
X
X
X
X
X
X
X
6
5
4
3
2
R-COUNTER’s Divide
Ratio
X
X
X
X
X
X
R5
R4
R3
R2
R1
1
0
C2
C1
1
0
Note: X = Don’t Care Condition
Reference Counter Divide Ratio (R-Counter)
Divide Ratio, R
R5
R4
R3
R2
R1
3
0
0
0
1
1
4
0
0
1
0
0
*
*
*
*
*
*
31
1
1
1
1
1
Note: Divide ratio must be from 3 to 31.
Pulse Swallow Function
fvco:
B:
A:
fOSC:
R:
P:
Output frequency of external voltage controlled oscillator (VCO)
Preset divide ratio of binary 7-bit programmable counter (3 to 127)
Preset divide ratio of binary 6-bit swallow counter (0 ≤ A ≤ P, A ≤ B)
Output frequency of the external reference frequency oscillator
Preset divide ratio of binary 5-bit programmable reference counter (3 to 31)
Preset modulus of dual modulus prescaler (32 or 64)
Receiver Functional Description
The simplified block diagram below shows the mixer, IF amplifier, limiter, and discriminator. In addition, the DC compensation circuit, doubler, and voltage regulator for an external LNA stage are shown.
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LMX3162
Receiver Functional Description
(Continued)
DS100929-5
Note 18: The receiver can be powered down, either by hardware through the Rx PD pin, or by software through the programming of F6 bit in the F-Latch. The power
down control method is determined by the settings of F11 and F12 in F-Latch. (Refer to Function Register Programming Description section for details.)
Note 19: The internal capacitor of the discriminator has a value of 1 pF, and has been optimized for operation at 110 MHz.
Transmitter Functional Description
The simplified block diagram below shows the doubler and voltage regulator for an external transmit gain stage.
DS100929-6
Note: The transmitter can be powered down, either by hardware through the Tx PD pin, or by software through the programming of F7 bith in F-Latch. The
power down control method is determined by the settings of F11 and F12 in F-Latch. (Refer to Function Register Programming Description section for details.)
Function Register Programming Description (F-Latch)
If the control bits are “1X”, data is transferred from the 20-bit shift register into the 18-bit F-latch. Serial data format is shown
below.
MSB
REGISTER’S BIT MAPPING
19
18
17
16
15
14
F18
F17
F16
F15
F14
F13
13
12
11
10
LSB
9
8
7
6
5
4
3
2
F8
F7
F6
F5
F4
F3
F2
F1
MODE CONTROL WORD
F12
F11
F10
F9
1
0
C2
C1
X
1
Note: X = Don’t Care Condition
Various modes of operation can be programmed with the function register bits F1–F18, including the phase detector polarity,
charge pump TRI-STATE and CMOS outputs. In addition, software or hardwire power down modes can be specified with bits F11
and F12.
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14
Mode
Control
Bit
Mode Control Description
(Continued)
Setting to
“0” to Select
Setting to
“1” to Select
32/33
64/65
Negative VCO
Characteristics
Positive VCO
Characteristics
F1
Prescaler modules select.
F2
Phase detector polarity. It is used to reverse the polarity of
the phase detector according to the VCO characteristics.
F3
Charge pump current gain select.
LOW Charge Pump
Current (1X Icpo).
HIGH Charge Pump
Current (4X Icpo).
Normal Operation
Force to TRI-STATE
F4
TRI-STATE charge pump output.
F5
Reserved. Setting to “0” always.
F6
—
—
Receive chain power down control. Software power down
can only be activated when both F11 and F12 are set to “0”.
Power Up RX Chain
Power Down RX Chain
F7
Transmit chain power down control. Software power down
can only be activated when both F11 and F12 are set to “0”.
Power Up TX Chain
Power Down TX Chain
F8
Out 0 CMOS output.
OUT 0 = LOW
OUT 0 = HIGH
F9
Out 1 CMOS output. Functions only in software power down
mode, when both F11 and F12 are set to “0”.
OUT 1 = LOW
OUT 1 = HIGH
F10
Out 2 CMOS output. Functions only in software power down
mode, when both F11 and F12 are set to “0”.
OUT 2 = LOW
OUT 2 = HIGH
F11
F12
Power down mode select.
Set both F11 and F12 to “0” for software power down mode.
Set both F11 and F12 to “1” for hardwire power down mode.
Other combinations are reserved for test mode.
Software
Power Down
Hardware
Power Down
F13
Demodulator gain select
F14
Demodulator DC level shift +/− level shifting polarity
F15
1X Gain Mode
3X Gain Mode
Set Negative Polarity
Set Positive Polarity
Demodulator DC level shift of 1.000V
No Shift
Shift the DC Level
by 1.000V
F16
Demodulator DC level shift of 0.500V
No Shift
Shift the DC Level
by 0.500V
F17
Demodulator DC level shift of 0.250V
No Shift
Shift the DC Level
by 0.250V
F18
Demodulator DC level shift of 0.125V
No Shift
Shift the DC Level
by 0.125V
Power Down Mode/Control Table
Software Power Down Mode (F11=F12=0)
Pin/Bit
Setting to “0”
means
Hardwire Power Down Mode (F11=F12=1)
Setting to “1”
means
Pin/Bit
Setting to “0”
means
Setting to “1”
means
F6
Receiver ON
Receiver OFF
Rx PD
Receiver OFF
Receiver ON
F7
Transmitter ON
Transmitter OFF
Tx PD
Transmitter OFF
Transmitter ON
PLL PD
PLL ON
PLL OFF
PLL PD
PLL ON
PLL OFF
CE
LMX3162 OFF
LMX3162 ON
CE
LMX3162 OFF
LMX3162 ON
15
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LMX3162
Function Register Programming Description (F-Latch)
LMX3162
Typical Application
DS100929-7
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16
LMX3162
Loop Filter Design Consideration
DS100929-8
FIGURE 1. Conventional PLL Architecture
PASSIVE LOOP FILTER
Open loop gain = H(s) G(s) =
θi/θe = Kφ Z(s)K VCO/Ns
Loop Gain Equations
A linear control system model of the phase feedback for a
PLL in the locked state is shown in Figure 2. The open loop
gain is the product of the phase comparator gain (K φ ), the
VCO gain (Kvco/s), and the loop filter gain Z(s) divided by the
gain of the feedback counter modulus (N). The passive loop
filter configuration used is displayed in Figure 3, while the
complex impedance of the filter is given in Equation (2).
(1)
(2)
The time constants which determine the pole and zero frequencies of the filter transfer function can be defined as
(3)
and
T2 = R2 • C2
(4)
The 3rd order PLL Open Loop Gain can be calculated in
terms of frequency, ω, the filter time constants T1 and T2,
and the design constants Kφ, Kvco, and N.
DS100929-9
FIGURE 2. PLL Linear Model
(5)
From Equations (3), (4) we can see that the phase term will
be dependent on the single pole and zero such that the
phase margin is determined in Equation (6).
DS100929-10
φ (ω) = tan
FIGURE 3. Passive Loop Filter
17
−1
(ω • T 2) − tan−1 (ω • T 1) + 180˚
(6)
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LMX3162 Single Chip Radio Transceiver
Physical Dimensions
inches (millimeters) unless otherwise noted
48-Lead (7mm x 7mm) Molded Plastic Quad Flat Package, JEDEC
For Tape and Reel (2500 Units per Reel)
Order Number LMX3162VBH or LMX3162VBHX
NS Package Number VBH48A
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