Typical values:
RV(diode video impedance) ≈ 1.5 kΩ*
C
B
(RF bypass capacitor) ≈ 27 pF nominal
TR (10 to 90% risetime) ≈ 2.2 (R
LOAD
) (RV)
(CB+ C
LOAD
) =
0.35
R
LOAD
+ R
V
BW
Agilent 8474B/C/E
Coaxial GaAs Microwave
Detectors
0.01 to 50 GHz
Data Sheet
Figure 1. Equivalent circuit for
8474A/B/C/D/E with typical parameters
Features and description
• Exceptional flatness
• Broadband from 0.01 to 50 GHz
• Extremely temperature stable
• Environmentally rugged
The 8474 series of coaxial detectors
are specifically designed for use in
microwave instrumentation and
systems. These detectors utilize a
GaAs diode matched to a 50 ohm
transmission line with a miniature
thin film circuit.
The diodes are a Planar-Doped Barrier
(PDB) structure fabricated by use of
Molecular Beam Epitaxy technology.
This combination yields a device which
has superior characteristics to
point-contact and low-barrier Schottky
devices. These characteristics are
reflected in frequency response
specification and in square law
response vs. frequency (Figure 7)
with PDB detectors showing a
maximum square law response
variation of 3% from 2 to 18 GHz vs.
9.5% for Schottky detectors.
These detectors are extremely rugged
with high resistance to ESD damage
and are less sensitive to temperature
change than either point-contact or
Schottky diodes. These products offer
10 MHz to 50 GHz performance with
the 2.4 mm connector (8474E) or narrower frequency coverage with APC-7
Type N or SMA-compatible 3.5 mm and
2.92 mm connectors. There is no need
to order matched pairs because the
frequency tracking is better than the
original matched pair specifications.
*@ 25˚ C and PIN ≤ 20 dBm (see Figure 7)
2
Detector performance characteristics
Figure 2. Typical transfer characteristics (Ta = 25° C).
Figure 3. Typical square law deviation.
Figure 4. Typical tangential sensitivity.
Figure 5. Typical output response with temperature. (Pin ≤20 dBm)
Figure 6. Typical video impedance variation with temperature.
Figure 7. Typical square law deviation due to frequency.
Loading...