National Semiconductor LMX2324, Руководство по эксплуатации, Страница: 2 / 17

L M X 2 3 2 4 E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S
LMX2324 2 March 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.