5-18 Keysight N5224A/25A Service Guide
Theory of Operation
Signal Separation Group Operation
5-
— the A34 test port 3 coupler and the A28 mixer brick receiver C
— the A35 test port 4 coupler and the A28 mixer brick receiver D
— the A36 test port 2 coupler and the A27 mixer brick receiver B
Normal Measurement Configuration
For those models equipped with a configurable test set and source
attenuators, with the inclusion of an external amplifier and accessories, you
can calibrate the analyzer and test devices at power levels up to +30 dBm. You
can make measurements in the forward, reverse, or both directions and still
achieve these high power levels.
High Dynamic Range Measurement Configuration
With a few jumper changes, you can configure the measurement configuration
for higher dynamic range measurements. By swapping the front panel jumpers
for one port, signal flow through the corresponding coupler is reversed,
increasing the test signal sensitivity by 15 dB.
In the forward direction, for example, the signal flow through the test port 2
coupler (A36) is reversed by arranging the front panel jumpers such that RCVR
B IN connects to CPLR THRU and CPLR ARM connects to SOURCE OUT.
While increasing forward (S21) dynamic range, the reverse (S12) dynamic
range is degraded by the same amount.
A29–A32 Receiver Couplers
The source incident signals from the A5 and A10 26.5 GHz sources are sent to
the A29–A32 receiver couplers where a portion of each signal is coupled off to
provide the R1, R2, R3, and R4 receiver reference signals for 4-port models or
R1 and R2 reference signals for 2-port models.
These reference signals are routed through front-panel jumpers to the A27 and
A28 mixer bricks. Refer to
“A27 and A28 Mixer Bricks” on page 5-22
additional information.
The test signals each go through the through-line arm of a receiver coupler,
then through a front panel jumper to the A33–A36 test port couplers.
A33–A36 Test Port Couplers
The test signals go into the through-line arm of the couplers, and from there to
the test ports and the DUT.
The coupled arm of the couplers carries the signal reflected from or
transmitted through the DUT, to the receiver for measurement (through front
panel jumpers), as inputs A, B, C, and D for 4-port models or inputs A and B for
2-port models. The coupling coefficient of the directional couplers is nominally
15 dB for all frequencies above 500 MHz. The coupling coefficient increases for
frequencies below 500 MHz.
