User`s guide

2-39
Making Mixer Measurements
Conversion Compression Using the Frequency Offset Mode
Conversion Compression Using the Frequency Offset 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.
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:
4. To set the analyzer to the desired power sweep range, press:
Preset
Sweep Setup
SWEEP TYPE MENU
POWER SWEEP
Return
System
INSTRUMENT MODE
FREQ OFFS MENU
LO MENU
FREQUENCY: CW
800 M/µ
Power
PWR RANGE MAN
POWER RANGES
RANGE 0
Start −10 x1
Stop 10 x1