Conversion Loss Using The Frequency Offset Mode - Agilent Technologies 8753ET User Manual

Conversion Loss Using the Frequency Offset Mode

Conversion loss is the measure of efficiency of a mixer. It is the ratio of side-band IF power
to RF signal power, and is usually expressed in dB. (To express ratios in dB, the dBm
power in the denominator must be subtracted from the dBm power in the numerator.) The
mixer translates the incoming signal, (RF), to a replica, (IF), displaced in frequency by the
local oscillator, (LO). Frequency translation is characterized by a loss in signal amplitude
and the generation of additional sidebands. For a given translation, two equal output
signals are expected, a lower sideband and an upper sideband.
Figure 2-10 An Example Spectrum of RF, LO, and IF Signals Present in a
Conversion Loss Measurement
The following procedure describes the swept IF frequency conversion loss measurement of
a broadband component mixer:
1. Set the LO source to the desired CW frequency of 1000 MHz and power level to 13 dBm.
2. Set the analyzer's LO frequency to match the frequency of the LO source by pressing:
INSTRUMENT MODE
System
FREQUENCY: CW 1000
3. Set the desired analyzer RF power to the value which will provide −10 dBm or less to
the R channel input. Press:
Power
PWR RANGE MAN
0 x1
4. Calibrate and zero the power meter.
5. Connect the measurement equipment as shown in Step 1 of
CAUTION To prevent connector damage, use an adapter (part number 1250-1462) as a
connector saver for R CHANNEL IN.
Conversion Loss Using the Frequency Offset Mode
FREQ OFFS MENU LO MENU
M/µ
Making Mixer Measurements
Figure 2-11.
2-13