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Overview
Looking at the Block
Diagram
Table 13-9
CAUTION
Block Diagram
HP 70428A Microwave Deck Assembly
HP 70428A Microwave Deck Assembly
The HP 70428A Microwave Deck (Assembly A5) generates a low-noise
microwave reference signal from 2.4 GHz to 26.4 GHz in 600 MHz steps,
with an adjustable output level of 0 dBm to +20 dBm. The reference signal
generator is the basis of the HP 7042x family of products.
The microwave signal is generated by amplifying the 600 MHz Reference
output to 1 watt, and then bandpass filtering the 600 MHz signal to remove
noise sidebands and harmonics beyond a 20 MHz carrier offset. The 600
MHz signal is then frequency multiplied to microwave by a Step Recovery
Diode (SRD) comb generator. The harmonic output level of the comb
generator is enhanced by a GaAs edge-sharpening transmission line, which
is terminated with a 3 dB attenuator. The desired comb frequency is now
selected with a three resonator YIG-Tuned-Filter (YTF). With the undesired
comb lines removed, the desired signal is amplified by a pre-amplifier and a
power amplifier microcircuit to the required level.
600 MHz Power Amplifier
The 600 MHz power amplifier is a high gain, high efficiency, Class A, 1
Watt amplifier designed to provide broadband power in low noise power
applications. This two stage hybrid amplifier uses silicon bipolar technology
and incorporates input/output blocking capacitors, bias network, and is
Ω.
matched to 50
Amplifier's Typical Residual Phase Noise Performance
Carrier Offset (Hz)
Residual Phase Noise
The amplifier's low-noise bias voltage is supplied by the A7A2 600 MHz
assembly, and is connected to the amplifier's RF input cable.
The 600 MHz coax cable between the 600 MHz reference output and the 600
MHz power amplifier input has a DC bias voltage of 13.6 V, capable of
delivering several amps of current. Appropriate DC blocking must be in
place when measuring the RF signal on this cable.
13-32 HP 70427A/HP 70428A User's Guide
1
10
100
–123
–137
–153
1 k
10 k
>100 k
–167
–175
–180
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