National Semiconductor LMX2324 User manual

REV C 7/28/98
LMX2324 March 5, 1999
LMX2324 Evaluation Board Operating Instructions
General Description
The LMX2324 Evaluation Board simplifies the evaluation of the LMX2324 2.0GHz PLLatinum frequency
synthesizer. It enables all performance measurements, with no additional support circuitry.
The board consists of a LMX2324 device, a VCO module and a loop filter built by discrete components. The SMA
flange mount connectors are provided for external reference input, RF output and the power & grounding
connection. A cable assembly is bundled with the evaluation board for connecting to PC through the parallel
printer port. By means of uWire serial port emulation, the Code Loader software included can be run on PC to
facilitate the LMX2324 internal register programming for the evaluation and measurement.
Loop Filter Illustration
Type 2 third order passive loop filter configuration is employed on the LMX2324 evaluation board. The loop filter
was designed based on the assumption of 12kHz loop bandwidth, 50 degree phase margin, 200kHz reference
frequency, and 10dB of attenuation. The actual implementations are shown as below:
C1
C2
C3
R2
R3
DoRF RF VCO
LOOP FILTER
C1 = 1200pF
C2 = 8200pF
R2= 4.7kohm
R3 = 15kohm
C3 = 120pF

LMX2324 EVALUATION BOARD OPERATING INSTRUCTIONS
LMX2324 2March 5, 1999
Quick Start
The LMX2324 Evaluation Board is fully assembled and factory tested. Follow the instructions below to set up the
hardware platform for the measurement of interest.
Recommended Test Equipment
• Spectrum analyzer with 10MHz reference output (operating frequency range > 2 GHz)
• Modulation domain analyzer
• DC power supply with adjustable voltage outputs
• 10MHz signal source/generator (optional, in case no reference output from spectrum analyzer)
Connection and Setup
1. Connect the RF_OUT output port to the input of a spectrum analyzer for phase noise and reference spur
measurement or the input of a modulation analyzer for lock time measurement.
2. Connect a oscillator reference to the OSCIN input port. It is advised to use a high quality reference source for
an accurate and low noise measurement. A 10MHz reference is generally available from most of the spectrum
analyzer at the reference output port.
3. Plug the DB25 connector end of the cable assembly to the parallel port of the PC. Connect the other end of the
cable to the on-board 3x2 pin header. Reder to the “Data Calbe Configuration” Section of the “Application
Information, Code Loader Operation” for pin 1 position.
4. Put jumper blocks to shunt pins 1 & 2 and 3 & 4 to connect Vp and VCO_Vcc
5. Turn on the DC power supply and adjust the voltage output to 3 Volt. Turn off supply.
6. Connect the DC power supply output to Vcc port of evaluation board. Turn on supply.
7. Turn on the signal generator and set the reference output frequency to 10MHz.
8. Run the Code Loader software on the PC for LMX2324 register programming. Refer to Appendices C and D
for more details.
Phase Noise Measurement Using A Spectrum Analyzer
1. Use the Code Loader software to set the desired frequency and to program the LMX2324 device. Refer to
Appendix C for more details.)
2. Set the spectrum analyzer to the desired center frequency and adjust the span so the appropriate offset frequency
can be viewed.
3. Turn on the video averaging feature of the analyzer for better determination of the noise level.
4. The difference between the level of the carrier and the noise level minus 10[log(resolution bandwidth)] is equal
to the phase noise in dBc/Hz. The resolution bandwidth can be read directly from the spectrum analyzer.

LMX2324 EVALUATION BOARD OPERATING INSTRUCTIONS
LMX2324 3March 5, 1999
Reference Spur Measurement Using A Spectrum Analyzer
1. Use the Code Loader software to set the desired frequency and to program the LMX2324 device. Refer to
Appndix C for more details.)
2. Set the spectrum analyzer to the desired center frequency and set the span to allow the reference sidebands to be
viewed. For example, the span can be set to 500kHz during the measurement as its loop filter design is based on
200kHz reference frequency.
3. The reference spur is the difference between the level of the VCO output frequency tone and the level of the
reference spur (at the center frequency +/- the reference frequency).
Lock Time Measurement Using A Modulation Domain Analyzer
1. Decide the maximum and minimum frequency to be switched to and from. The VCO operating frequency
range can be obtained in Appendix D. Enter Burst Mode menu of Code Loader software to create a macro to
program the LMX2324 to the maximum and minimum frequency alternatively over time. It is necessary to put
sufficient delay between PLL switching (ie 100,000). Refer to the “Burst Mode Configuration and Operation”
Section of the “Application Information, Code Loader Operation” for more details.
2. Set the center frequency of the modulation domain analyzer to be half way from the maximum and minimum
frequencies. Set the frequency span to cover the entire frequency range. A switching signal should be seen on
the screen.
3. Set the center frequency to be the trigger condition for One-Shot mode. Press [Start/Stop] button to capture
the switching curve. Adjust the frequency and time scale accordingly to get a close-up plot for detailed
information.
4. The lock time is the time difference between the point the frequency starts to change and the point that the PLL
frequency settles within +/- 1kHz range.

LMX2324 EVALUATION BOARD OPERATING INSTRUCTIONS
LMX2324 4March 5, 1999
LMX2324 Performance Measurement Result – A Typical Example
Reference spurs
Fvco = 1930 MHz Fvco = 1960MHz
╪ ╪
╪
╪
╪ ╪╪╪
╪╪
╪
╪╪
╪╪
╪
╪ ╪
╪
╪
╪ ╪╪╪
╪
╪
╪╪
╪
╪
Fvco = 1990 MHz
╪ ╪
╪
╪
╪ ╪╪╪
╪╪
╪
╪╪
╪╪
╪

LMX2324 EVALUATION BOARD OPERATING INSTRUCTIONS
LMX2324 5March 5, 1999
LMX2324 Performance Measurement Result – A Typical Example (continued)
Phase Noise (measured at 150Hz offset)
Fvco = 1960 MHz
╪ ╪ ╪ ╪
╪╪
╪
╪ ╪╪╪ ╪╪ ╪╪
╪
╪
Loop bandwidth
Fvco=1960MHz
╪
╪
╪
╪
╪
╪╪╪╪ ╪ ╪
╪
╪

LMX2324 EVALUATION BOARD OPERATING INSTRUCTIONS
LMX2324 6March 5, 1999
Lock Time Measurement Result
Positive Frequency Switching Waveform
Positive Lock Time to within 1 kHz Range

LMX2324 EVALUATION BOARD OPERATING INSTRUCTIONS
LMX2324 7March 5, 1999
Lock Time Measurement Result (Cont.)
Negative Frequency Switching Waveform
Negative Lock Time to within 1kHz Range

LMX2324 EVALUATION BOARD OPERATING INSTRUCTIONS
LMX2324 8March 5, 1999
MEASUREMENT CONDITIONS
The LMX2324 Evaluation Board has been tested to meet the typical performance criteria as shown below:
Testing Condition
VCC Operating Voltage : 3.0 Volt
VCO Tuning Range : 1930 - 1990 MHz
RF Comparison Frequency : 200 kHz
Typical Performance Criteria
VCO Phase Noise : Less than -70 dBc/Hz @ 150Hz
VCO Reference Spur : Less than -60 dBc @ 200kHz
VCO Lock Time : Less than 500 us (within +/- 1kHz settling frequency)
Remark
Computer monitors and other lab equipment has been shown to cause noise spikes. If you see noise spikes on
the signal, try turning off the monitor or other equipment to verify that they are not the cause. Also noise
may be getting onto the signal through the cable that connects to the parallel port of the computer.
Disconnecting the cable may eliminate the noise.

REV C 7/28/98
LMX2324 March 5, 1999 Appendix A - LMX2324 Evaluation Board Schematic Diagram
Title
Number RevisionSize
A
Date: 23-Jun-1998 Sheet of File: U:\MARY\..\2324TSSO.SCH Drawn By:
12
34
56
JP2 HEADER 3X2
C1
C3
C4
0.01uF
C6
100pF
C8
0.1uF
1 2 3 4
JP1
HEADER 2X2
1
Vcc
C5
0.01uF
C7
100pF
C9
0.1uF
1
Vp
C10
0.01uF
1
Ref In
1
RF Out
Vcc
1
Vp
2
CPo
3
GND
4
NC
7
fin_bar
5
fin
6
NC
8OSCin 9
NC 10 NC 11
Cloc k 12
Data 13
LE 14
NC 15
CE 16
U1
LMX2324TSSOP
C11 100pF
Vcc
R1 18
R4 18
R3
R2
R5 0
R6 51
R7
10k
R10
22k
R11 22k
R8
10k
R13 10k R12 22k
R9 10k
C12 100pF
C2
Vcc
3
2
16
5
4
U2 VCO_8PIN
R14 10
C13
100pF
C14
0.1uF
1
R15
o/c
R16
o/c
TSSOP BOARD

LMX2324 EVALUATION BOARD OPERATING INSTRUCTIONS LMX2324 10 March 5, 1999
1234
A
B C
D
4
321
D
C B
ATitle
Number RevisionSize
A
Date: 23-Jun-1998 Sheet of File: U:\MARY\..\2324CSP.SCH Drawn By:
Vp
1
CPo
2
GND
3
fin_bar
4
fin
5
NC
6
NC
7
OSCin
8
NC 9
Cloc k 10
Data 11
LE 12
NC 13
NC 14
CE 15
Vcc 16
U1
LMX2324CSP
C6 0.01uF
1 2 3 4
JP1
HEADER 2X2 R1
18
R4 18
C9 0.01uF
C10 100pF
C11 0.1uF C12 0.1uF
C13 100pF
1
Vp
1
Vcc
C1C2
R2
R3
C3
3
2
16
5
4
U2
R5 10
C14 100pF
C15 0.1uF
1
Vcc_VCO
C16 100pF
R6 0
R7 o/c
R8 o/c
1
RF Out
C17
0.01uF
1
Ref In
R9 50
R10 10k
R11 22k R12 22k
R13 10k R14 10k
R15 22k
1 2 3 4 5 6
JP2 HEADER 3X2
R16 10k
Vcc
Vcc
C4 100pF
CSP BOARD

LMX2324 EVALUATION BOARD OPERATING INSTRUCTIONS LMX2324 11 March 5, 1999 Appendix B - LMX2324 Evaluation Board Layout
TSSOP BOARD

REV C 7/28/98
LMX2324 March 5, 1999
CSP BOARD

REV C 7/28/98
LMX2324 March 5, 1999
Appendix C - How To Do Port Setup of Code Loader Software
The LMX2324 Evaluation board is designed so that port setup is required to be configured as follows except for
the Port Address. The Port Address should be selected according to the user PC parallel port.
FIGURE C-1: PORT SETUP FOR LMX2324 EVALUATION BOARD

LMX2324 EVALUATION BOARD OPERATING INSTRUCTIONS
LMX2324 16 March 5, 1999
Appendix D - LMX2324 Code Loader Main Menu Description
FIGURE D-1: "CODE LOADER" MAIN MENU FOR LMX2324
All parameter values or states can be changed except the charge pump states, FoLD option, and R counter prescalers.
The parameter boxes can be changed by just clicking on or by clicking on and entering new values. The user must
press Enter on the keyboard after the parameters are changed. Only registers for which the new changes are
relevant are loaded when the Enter is pressed. To load all registers in both RF and IF PLLs, select the Load - PLL
pull down menu or enter Ctrl + L.
Ref In - TCXO or reference crystal oscillator input. NSC's normal LMX2324 evaluation board is designed for a
10 MHz TCXO. The user is advised to use a high quality crystal reference for an accurate and low noise
measurement. A high quality 10 MHz reference signal is generally available from the most of spectrum analyzer
reference output port or signal generator reference output port.
Phase Detector - Phase detector (comparator) frequency. NSC's normal LMX2324 evaluation boards are
designed for a 200 kHz PLL phase detector frequency. The component values of the loop filter require redesign if
the user wishes to use other phase detector frequency.
PLL In - VCO output frequency (PLL fin input frequency). Operating frequencies for the VCO's used on NSC's
normal LMX2324 evaluation boards are as follows:
VCO used Operating frequency range [MHz]
LMX2324 Varil 1960 1930 - 1990

LMX2324 EVALUATION BOARD OPERATING INSTRUCTIONS
LMX2324 17 March 5, 1999
The user is allowed to enter a frequency within the VCO operating frequency range. The component values of the
loop filter should be redesigned if the user wishes to use other VCOs.
Prescale - Prescaler value of the counters. There is no prescaler used in the R counter, which is indicated by 1.
Availability of the prescaler values depends on the user's device type. Refer to the data book for the available
prescaler values. The prescaler value can be changed by clicking on the Prescale box.
Phase Detector Polarity - The polarity can be changed by clicking on the "+" or "-". Refer to the data sheet for the
description of this function.
Charge Pump Gain - Charge pump output current. The LMX2324 has only one charge pump mode.
Auto Reload Every [XX] sec - Time interval the program reloads all the counters. The user enables the reload
function by selecting Options - Auto Reload from the pull down menu.
Program Pins - Trigger - External Trigger for the programming port. The programming port assigned for Trigger
becomes high when selected and port goes low when not selected.
Program Pins - PLL En - Signal to control on and off of the LMX2324. On the LMX2324 evaluation board, PLL
En is not utilized and PLL is on all the time through a 10k pull-up resistor to Vcc.
Program Bits - Pwr Dn - Synchronously powers down the LMX2324.
Program Bits - Reset - Resets both N and R counters. Upon powering up the N counter resumes counting in close
alignment with the R counter.
Program Bits - R13 - This is a reserved bit and should be set to zero always
Program Bits - R14 – This is a test mode bit that allows either R or N counter output to be observed at the charge
pump output. Refer to the datasheet for more information.