2-40
Making Mixer Measurements (Option 089 Only)
Conversion Compression Using the Frequency Offset Mode
Conversion Comp ression Using th e Frequency Offs et Mode Conversion compression is a measure of the maximum RF input signal level where the
mixer provides linear operation. The conversion loss is the ratio of the IF output level to
the RF input level. This value remains constant over a specified input power range. When
the input power level exceeds a certain maximum, the constant ratio between IF and RF
power levels will begin to change. The point at which the ratio has decreased by 1 dB is
called the 1 dB compression point. See Figure 2-27.
Figure 2-27 Conversion Loss and Output Power as a Function of Input Power
Level Example
Notice that the IF output power increases linearly with the increasing RF signal, until
mixer compression begins and the mixer saturates.
The following example uses a ratio of mixer output to input power and a marker search
function to locate a mixer’s 1 dB compression point.
NOTE Because this procedure was performed with an 8719ES/20ES, Option 007, the
analyzer was able to produce an output power of +10 dBm.
If the default output power of your analyzer is not high enough to force the
mixer under test into compression, then the following procedure may have to
be performed with the addition of Option 007 or Option 085. Refer to the
"Making High Power Measurements with Option 085 (ES Analyzers Only)"
on page 1-59.
1. Set the LO source to the desired CW frequency of 600 MHz and power level to 13 dBm.
2. Initialize the analyzer by pressing .
3. Set the analyzers LO frequency to match the frequency of the LO source by pressing:
Preset
Sweep Setup
SWEEP TYPE MENU
POWER SWEEP
Return