Texas Instruments High Performance Frequency Synthesizer System with Integrated VCO LMX25311515EVAL/NOPB LMX25311515EVAL/NOPB 데이터 시트
제품 코드
LMX25311515EVAL/NOPB
L M X 2 5 3 1 L Q 1 3 1 2 E 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
Troubleshooting
Problem Corrective
Actions
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All Modes
• Ensure a valid signal is presented to the OSCin connector. If a signal
generator is used, ensure the RF is ON.
• Consult the CodeLoader instructions for more detailed information on
communication issues
LPT Mode (Uses Parallel Port Cable)
• Ensure CodeLoader is set to LPT mode on the Port Setup tab.
• Ensure the proper port number is selected (LPT1, LPT2, LPT3). CodeLoader
does NOT automatically detect this.
• Ensure the LPT cable is securely connected to the computer and board.
• Exit and Restart CodeLoader.
• Ensure the parallel port is in the correct mode
o Windows often requires Administrative access to write to the parallel
port.
o Ensure that the parallel port is set to “Enabled” in windows device
manager.
o A reboot upon installation of CodeLoader is sometimes necessary to
get the parallel port to work.
o Standard mode is the most reliable. This can be set in the BIOS mode
of the computer as “Normal”, “Output Only”, or “AT”.
USB Mode (Uses USB to Parallel Port Converter)
• On the menu, select USB->Version to verify communication with the board.
• Ensure the Green LEDs are lit on the USB board.
• Ensure there is no conflicts with other USB devices and reinstall the board.
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• Ensure there is a valid signal presented to the OSCin connector. If a signal
generator is used, ensure that the RF is set to ON.
• If using the lower frequency band (DIV2=1), the VCO frequency in CodeLoader
should be twice the frequency at the Fout pin.
• Ensure the VCO FREQUENCY CAL bits on the Bits/Pins tab are correct.
• Ensure the loop filter is optimized if the charge pump current, phase detector
frequency, or loop filter values have been changed from their original settings.
Ensure the integrated loop filter components on CodeLoader are set to their
proper settings.
Ensure the integrated loop filter components on CodeLoader are set to their
proper settings.
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• Ensure the signal presented to the OSCin connector is clean. Try another
source, or if it is a signal generator, try using a higher frequency and dividing it
down to the required phase detector frequency.
down to the required phase detector frequency.
• Ensure the OSCin signal and cable provides sufficient power level.
• If the phase detector frequency or charge pump current is lowered from its’
original setting, the in-band phase noise can be degraded even if the loop filter
is re-designed for the same loop bandwidth. If the loop bandwidth is
decreased, in-band phase noise can be degraded.
is re-designed for the same loop bandwidth. If the loop bandwidth is
decreased, in-band phase noise can be degraded.
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• Ensure the measurement equipment noise floor is not limiting the
measurement. For spectrum analyzers, the noise floor at a particular setting
can be measured by removing the RF input signal.
can be measured by removing the RF input signal.
• If the settings are changed from what the board was designed for, ensure the
delta-sigma modulator is not increasing the far-out noise. To determine this,
tune to an integer channel and set the ORDER bit to “Reset Modulator”. The
far out phase noise should not decrease. If a decrease occurs, try a loop filter
with more attenuation or select a lower order delta-sigma modulator.
tune to an integer channel and set the ORDER bit to “Reset Modulator”. The
far out phase noise should not decrease. If a decrease occurs, try a loop filter
with more attenuation or select a lower order delta-sigma modulator.
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