Keysight CXG, EXG, and MXG X-Series Signal Generators Service Guide 229
Micro-Deck Assembly
A7 Micro-Deck Assembly Overview
For frequencies above 20 GHz the A7A4 40 GHz Doubler is used to double the
10 GHz to 20 GHz output of the A7A2 20 GHz Frequency Multiplier.
The 3.2 GHz to 20 GHz output of the A7A2 Frequency Multiplier assembly is at
a fixed amplitude level.
The output of the A7A2 Frequency Multiplier is routed to the A7A3 Mod-Filter
assembly which contains the ALC modulator, pulse modulator, amplifiers, and
a bank of lowpass filters. The drive voltages for the modulators comes from the
A7A1 Microwave ALC assembly.
For instrument with option 532 (31.8 GHz) or 540 (40 GHz) the A7A4 40 GHz
Doubler assembly is also included. This takes the 10 GHz to 20 GHz output of
the A7A3 Mod-Filter and multiplies it by two to produce the 20 GHz to 40 GHz
frequencies.
The signal is then routed to the A7A5 Directional Coupler that has the A7A6
High Band Detector attached to the coupled port. While all frequencies pass
through the A7A5 Directional Coupler, the A7A6 High Band Detector is only
used for frequencies of 2 GHz and above. The output of the A7A6 High Band
Detector is routed to the A7A1 Microwave ALC assembly.
The signal is then routed to the A7AT1 Attenuator. Instruments with option 1E1
(Step Attenuator) have the ability to use the A7AT1 Attenuator to reduce the
power level of the signal beyond the range of the ALC modulators. Instruments
without option 1E1 still have the A7AT1 Attenuator installed in them, but it will
always be set to bypass all of the internal attenuator sections.
Automatic Level Control
For an overall description of the Automatic Leveling Control (ALC) system see
the “Automatic Level Control Section” in Chapter 10, “RF Assembly”
The microwave instruments have the ability to be hardware leveled by either
the internal ALC detectors or an external detector. For internal leveling there
are three band breaks in the ALC circuitry.
5 MHz to <2.0 GHz
In this frequency range the ALC detector and modulators used are both on the
A3 RF assembly.
2.0 GHz to <3.2 GHz
Desired Output Frequency Multiplier Input Frequency
3.2 GHz to 5 GHz 1 3.2 GHz to 5 GHz
5 GHz to 10 GHz 2 2.5 GHz to 5 GHz
10 GHz to 20 GHz 4 2.5 GHz to 5 GHz
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