Circuit Note

CN-0518

analog.com

Rev. 0 | 7 of 8

The procedure for measuring S-Parameters and the noise figure

are as follows:

1. Set the measurement conditions of the vector network analyzer

as follows:

a. Set the frequency span from 902 MHz to 928 MHz.

b. Set the frequency step size to 10 kHz.

c. The power level must be less than or equal to -30 dBm.

2. Perform a full 2-port calibration of the vector network analyzer

using a calibration kit. Note that the RF output of the EVAL-

CN0518-EBZ can be connected directly to a test port, so that

only one measurement cable is needed for the test setup.

3. Connect the EVAL-CN0518-EBZ across the test ports of the

vector network analyzer using the calibrated test setup.

4. Power up the EVAL-CN0518-EBZ using the 5 V power adapter.

5. Set the vector network analyzer to display the traces of the

individual S-Parameters and the noise figure.

6. Compare the measurements to the expected values. At 915

MHz center frequency, the values for input and output return

losses are approximately -20 dB and -12 dB, respectively. For

the gain and noise figure readings, values should be approxi-

mately 25 dB and 0.8 dB, respectively.

Figure 19 shows the functional block diagram for the phase noise

and SFDR test setup.

Figure 19. Phase Noise and SFDR Test Setup

To perform the phase noise and SFDR tests, follow the steps

below:

1. Set the measurement configuration of the signal analyzer as

follows:

a. For SFDR measurement, set the center frequency to 915

MHz, the frequency span to 902 MHz to 928 MHz, and the

RF amplitude to -30 dBm.

b. For phase noise measurement, set the center frequency to

915 MHz and the offset frequency range to 10 Hz to 30

MHz.

2. Set the power level of the signal generator between -30 dBm to

-20 dBm with a center frequency set at 915 MHz.

3. Connect the signal generator output to the RF input of the

EVAL-CN0518-EBZ.

4. Connect the RF output of the EVAL-CN0518-EBZ to the signal

analyzer.

5. Power up the EVAL-CN0518-EBZ using the 5 V power adapter.

6. Execute a measurement run on the signal analyzer.

7. Using the signal analyzer, get the phase noise value and verify

if it is approximately -129 dBc/Hz at 100 kHz offset.

8. Run the SFDR test and compare the readings; expected value

is approximately 76 dBFS.