Frequency Generation - Agilent Technologies E8267C Service Manual

not installed.

Frequency Generation

The YIG oscillator generates frequencies from 3.2 to 10 GHz.
Output Oscillator
Frequency Frequency
< 250 MHz 3.2 to 10 GHz
100 kHz
to 4 to 8 GHz
3.2 GHz
> 3.2 GHz 3.2 to 10 GHz
Highband Path – Frequencies 3.2 GHz and Above
The output of the YIG oscillator (3.2 to 10 GHz) is routed to the A29 20 GHz Doubler microcircuit.
Depending on the desired output frequency, the signal is routed either through a bypass circuit (for
frequencies <10 GHz), or through a frequency doubler circuit (for frequencies >10 GHz). After the
bypass or doubler circuits, the signal is amplified and filtered.
The 20 GHz Doubler output is routed first to either the A30 Modulation Filter (in analog models) or
the A35 3–20 GHz I/Q Modulator (in digital models), and then to the A30 Modulation Filter. The
A30 contains amplitude and pulse modulators, amplifiers, and filters. The A35 3–20 GHz I/Q
Modulator contains I and Q modulation circuits used to transfer the I/Q information to the RF
signal.
In 20 GHz models, the output of the A30 Modulation Filter is routed to the A24 Highband Coupler
and A25 Highband Detector, then either through the optional AT1 attenuator to the front panel RF
output connector, or directly to the RF output connector.
In 40 GHz analog models, the A30 Modulation Filter output is routed to the input of the
A27 40 GHz Doubler for frequencies above 20 GHz, and to a bypass switch in the A27 40 GHz
Doubler for frequencies up to 20 GHz. The output of the A27 40 GHz Doubler is connected to the
A24 Highband Coupler and A25 Highband Detector, to the optional AT1 attenuator, and to the front
panel RF output connector.
Lowband Path – Frequencies Below 3.2 GHz
For frequencies below 3.2 GHz, the YIG oscillator output is tuned between 4 and 8 GHz. The YIG
oscillator output is routed to the A29 20 GHz Doubler microcircuit, where a portion of the signal is
coupled off and routed to the A6 Frac–N. A divider on the A6 Frac–N divides the 4 to 8 GHz signal
to a frequency between 250 MHz and 3.2 GHz. This signal is then routed to the A8 Output assembly
where it is amplified, filtered and modulated.
Frequencies below 250 MHz are generated on the A8 Output by mixing the output signal from the
A6 Frac–N (between 1000 and 750 MHz) with a 1 GHz LO from the A7 Reference. In digital models,
the A8 Output also contains the I/Q modulation circuit.
Option 1E6 (Improved Pulse performance below 3.2 GHz) is installed after the A8 Output.
The signal (100 kHz to 3.2 GHz) is routed to the A23 Lowband Coupler/Detector, and then switched
into the highband path by a switch in the A30 Modulation Filter microcircuit. From this point, the
Path
A6 Frac–N signal is mixed with a 1 GHz signal on the A8 output assembly;
the difference is used to generate the lower frequencies.
Lowband path,
and part of
highband path
Oscillator output is divided by 2/4/8/16 on the A6 Frac–N assembly.
Highband path For frequencies between 10 and 20 GHz, the oscillator output is doubled.
For frequencies between 20 and 40 GHz, the 10 to 20 GHz signal is doubled.
Overall Description
Notes
Troubleshooting
1-87