Signal Separation - Agilent Technologies 8753ES Option 011 Service Manual

Theory of Operation

Signal Separation

Signal Separation
External Test Sets
The HP/Agilent 85047A S-parameter test set contains a switched frequency doubler to
double the analyzer's source frequency. A portion of the RF signal is coupled to the
analyzer R input for reference. (For analyzers with Option 006, the frequency doubler is
bypassed since the analyzer's source is capable of generating a swept RF signal up to
6 GHz.) The remaining signal is routed through a 70 dB programmable step attenuator to
the directional couplers for reflection and transmission measurements. The couplers allow
detection of the signal from 300 kHz to 6 GHz. These couplers provide low insertion loss
between the RF input and the test ports. Two bias tees supply external biasing for active
devices. Figure 12-9 includes a simplified block diagram of the 85047A.
The HP/Agilent 85046A/B S-parameter test set contains a power splitter to divert a
portion of the incident signal to the R input of the analyzer for reference. The remainder of
the incident signal is routed through a switch to one of two directional bridges at the
measurement ports. The RF path switch is controlled by the analyzer to enable switching
between forward and reverse measurements. A 70 dB step attenuator in the test set, also
controlled from the analyzer, adjusts the power level to the DUT without changing the
level of the incident power in the reference path. Two bias tees are included, for external
biasing of active devices connected to the test ports. Figure 12-9 includes a simplified block
diagram of the 85046A/B.
The HP/Agilent 85044A/B transmission/reflection test set contains a power splitter
to divert a portion of the incident signal to the R input of the analyzer. The remainder of
the incident signal is routed through a directional bridge to the measurement port. The
test set includes a manually controlled 70 dB step attenuator, and a bias tee for external
biasing of active devices connected to the test port. A simplified block diagram of the
85044A/B is included in Figure 12-9.
An HP/Agilent 11850C/D or 11667A power splitter can be used instead of a test set for
transmission measurements only.
12-26 Chapter 12