Amplifier measurement example
output power, and gain compression measurements procedures are covered. For more information on measuring amplifiers, refer to Agilent product note
Table 7. Absolute output power and 1 dB compression measurements of an amplifier
8510C KeystrokesDescription
Perform the
Set up the test port power level
STIMULUS [MENU] | Set the test port power below the amplifier’s compression level (PA) and within the settable power range presented |
{POWER MENU} | in Table 4. |
{POWER SOURCE 1} |
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PA [x1] |
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Set up a b2 measurement and connect a thru | |
PARAMETER [MENU] | Set up the analyzer for a b2 measurement. |
{USER 2 b2} |
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Perform a thru calibration |
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[CAL] | Perform a thru calibration to eliminate the frequency response errors of the port 2 path in the measurement. Be sure to |
{CAL#…} | include any attenuators and/or adapters which are part of the measurement in the thru calibration. It may be necessary |
{CALIBRATE:RESPONSE} | to swap adapters for the thru calibration. Any cal set may be selected to access the response calibration in the calibration |
{THRU} | menu structure. |
{DONE RESPONSE} |
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{CAL SET #} |
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Connect the amplifier and measure the absolute output power | |
RESPONSE [MENU] | Display the absolute power by entering a magnitude offset (PA) equivalent to the test port power level during the thru |
{MORE} | calibration. Gain can be calculated for any measurement point by subtracting Pin from Pout (or Pmeasured/PA). The gain |
{MAGNITUDE OFFSET} | can also be measured by performing an S21 measurement. |
PA [x1] |
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[AUTO] |
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Set up a 1 dB compression measurement and normalize the trace | |
[DISPLAY] | By normalizing the measurement, the first frequency point to drop by 1 dB will be easy to identify. |
{DATA AND MEMORIES} |
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{DISPLAY→ MEMORY 1} |
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{MATH(/)} |
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Adjust the display |
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[REF VALUE] | Move the reference line near the bottom of the grid to allow full use of the display. |
1 [x1] |
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[REF POSN] |
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USE DOWN ARROW |
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[SCALE] |
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1 [x1] |
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Increase power to find the 1 dB gain compression point | |
STIMULUS [MENU] | Increase the test port power 1 dB at a time until the trace visibly drops. Then use the knob to adjust the power until |
{POWER MENU} | a 1 dB drop in the trace occurs. Note the test port power and use a marker to measure the frequency. |
{POWER SOURCE 1} |
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USE UP ARROW |
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[MARKER] |
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Measure the absolute output power at the 1 dB compression point | |
[REF POSN] | Move the reference level back to the center of the screen and display the absolute output power versus frequency. |
[DISPLAY] | The marker will indicate the amplifier's absolute output power for the1 dB compression point. |
{DATA AND MEMORIES} |
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{DISPLAY:DATA} |
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[AUTO] |
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