Conversion Compression Using The Frequency Offset Mode; Conversion Loss And Output Power As A Function Of Input Power Level - Agilent Technologies 8719D User Manual

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 1 dB is called the 1 dB compression
point. See Figure 3-19.
Input Signal (RF)
Figure 3-19. Conversion Loss and Output Power as a Function of Input Power Level
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
function to locate a mixer's 1 dB compression point.
Because this procedure was performed with an HP 8719D/20D, Option 007, the
Note
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 Cption 007 or Option 085. Refer to the
"High Power Measurements" section in Chapter 2, "Making Measurements," for
information on using Option 085.
1. Set the Lo source to the desired CW frequency and power level.
CW frequency = 600 MHz
Power = 13 dI3m
2. Initialize the analyzer by pressing 1preset].
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