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National Semiconductor LMX2324 Operating Instructions Manual

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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 = 1200pF
C2 = 8200pF
R2= 4.7kohm
R3 = 15kohm
C3 = 120pF
LMX2324
R3
DoRF
C1
R2
C2
LOOP FILTER
R E V C 7 / 2 8 / 9 8
RF VCO
C3
March 5, 1999

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Summary of Contents for National Semiconductor LMX2324

  • Page 1 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.

  • Page 2: Quick Start

    I N S T R U C T I O N S 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 •...

  • Page 3: Reference Spur Measurement Using A Spectrum Analyzer

    I N S T R U C T I O N S Reference Spur Measurement Using A Spectrum Analyzer Use the Code Loader software to set the desired frequency and to program the LMX2324 device. Refer to Appndix C for more details.) Set the spectrum analyzer to the desired center frequency and set the span to allow the reference sidebands to be viewed.
  • Page 4 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 Performance Measurement Result – A Typical Example Reference spurs Fvco = 1930 MHz Fvco = 1960MHz ╪...

  • Page 5: Phase Noise

    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 Performance Measurement Result – A Typical Example (continued) Phase Noise (measured at 150Hz offset) Fvco = 1960 MHz ╪...
  • Page 6 O P E R A T I N G I N S T R U C T I O N S Lock Time Measurement Result Positive Frequency Switching Waveform Positive Lock Time to within 1 kHz Range LMX2324 March 5, 1999...
  • Page 7 O P E R A T I N G I N S T R U C T I O N S Lock Time Measurement Result (Cont.) Negative Frequency Switching Waveform Negative Lock Time to within 1kHz Range LMX2324 March 5, 1999...

  • Page 8: Measurement Conditions

    O P E R A T I N G I N S T R U C T I O N S MEASUREMENT CONDITIONS LMX2324 Evaluation Board has been tested to meet the typical performance criteria as shown below: Testing Condition VCC Operating Voltage 3.0 Volt...
  • Page 15 R E V C 7 / 2 8 / 9 8 Appendix C - How To Do Port Setup of Code Loader Software LMX2324 Evaluation board is designed so that port setup is required to be configured as follows except for the Port Address.
  • Page 16 O P E R A T I N G I N S T R U C T I O N S Appendix D - LMX2324 Code Loader Main Menu Description L M X 2 3 2 4 F I G U R E D - 1 : " C O D E L O A D E R " M A I N M E N U F O R All parameter values or states can be changed except the charge pump states, FoLD option, and R counter prescalers.
  • Page 17 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.

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