Agilent
84904/5/8M
Programmable Step Attenuators
for Microwave and RF Manufacturing
Test Systems
Product Overview
•
Excellent repeatability: <0.03dB typical
•
Low insertion loss: <2.6 dB @ 50 GHz (84905M)
•
Long life: >2 million cycles
Features and description
• DC to 50 GHz frequency coverage
• Optional calibration data
• 0 to 11 dB, 0 to 60 dB, 0 to 65 dB
• 1 dB steps, 10 dB steps, 5 dB
steps respectively
• High accuracy
• Excellent reliability
In today’s fast moving technical
industries, test engineers need
components they can count on.
Agilent now offers an extension
to its existing attenuators that
combine its legendary reliability
with a higher frequency (50 GHz)
capability.
Increase frequency
For test systems that require
increased frequency capability
(50 GHz) with variable attenuation
ranges and steps the M family of
attenuators has a solution that fits
your need. Options include:
• 84904M: 0 to 11 dB in 1 dB steps
(4 section)
• 84905M: 0 to 60 dB in 10 dB
steps (3 section)
• 84908M: 0 to 65 dB in 5 dB steps
(4 section)
Reduce downtime
Agilent Technologies is the
world leader in innovating and
developing microwave accessories
for communications and aerospace
applications. Our innovative
design and strict adherence to
quality process control ensure
that each attenuator is guaranteed
to perform within warranted
specifications for its entire lifetime.
With fewer breakdowns and less
need to recalibrate, your test
platform performs better with
less downtime, creating more
throughput and revenue.
Raise your standards
All Agilent attenuators offer
excellent repeatability and long
life – up to five times the lifecycles
of the competition. Along with our
aggressive specifications for SWR,
and insertion loss, you have an
attenuator that will exceed the
expectations of even the most
demanding engineer with its
precision and durability.
Increase productivity
When you buy your attenuators
from Agilent, you will notice a
difference. Your test platforms
will run smoother, longer, and
faster, while yielding more viable
and valuable measurements.
Description
These attenuators offer repeatability
of better than 0.03 dB and excellent
life (greater than 2 million
switching cycles per section).
The M family of programmable
step attenuators offers coaxial
measurements to 50 GHz in a
compact rugged design. The first
model is the Agilent Technologies
84904M, which offers outstanding
performance with an attenuation
range of 0 to 11 dB in 1 dB steps.
The next, high frequency model, is
the Agilent 84905M, which provides
a range from 0 to 60 dB in 10 dB
steps. Last, the Agilent 84908M
provides an attenuation range from
0 to 65 dB in 5 dB steps.
Agilent’s design, seen in the
84904/6/7K and L attenuators,
sets the standard for size and
performance. High attenuation
accuracy and low SWR are achieved
through the use of miniature thinfilm attenuation cards. Insertion
loss performance is outstanding,
with less than 3.0 dB of loss at
50 GHz. Their compact design
allows for easy integration into
instruments and ATE systems.
For operating to 50 GHz the
84904/5/8M models offer the
2.4 mm connector that is the best
solution for top performance as
well as rugged and repeatable
connections. Each model in the
84904/5/8M family comes with two
female connectors (Option 101) or
may be ordered with one female
and one male connector for easy
insertion into a microwave chain
(Option 100).
Individual calibration data reports of
attenuation and SWR are available.
This data, measured with an Agilent
automatic network analyzer, can
be ordered as Option UK6.
Attenuation switching and control
These units feature the same
small solenoids and switching
circuits as the Agilent Technologies
8494/5/6/7 step attenuator family.
Switching time is a maximum
of 20 milliseconds; this includes
contact settling time. Once switched,
the units are latched with permanent
magnets, capable of withstanding
shocks over 10 Gs. The solenoids
automatically disconnect after
switching, which minimizes the
attenuators’ power requirements
and simplifies the driver circuit
design. Solenoids are available in
either 24 volt (Option 024), 15 volt
(Option 015), and 5 volt (Option
011) ranges to fit your instrument or
system requirements.
The units come equipped with
10-pin DIP headers for connecting
DC control lines. Available
accessories include a 203 mm
(8 inch) or 406 mm (16 inch) ribbon
cable (11764-60002 or 11764-60003,
respectively) with DIP-type
connectors that are compatible
with standard 14-pin DIP IC sockets.
Alternately, a 1524 mm (5 foot)
cable (11764-60001) with free wires
for direct soldering, or a 1524 mm
(5 foot) drive cable that connects
to the 11713A attenuator/switch
driver, allowing for easy integration
into GPIB-controlled automatic
test sytems (11764-60004) may
be ordered.
2
Selection switching
Figure 2 shows one attenuator
section schematic. Each section
utilizes one solenoid with dual coil
windings, one coil to switch in the
attenuator card (e.g. 10 dB) and one
coil to switch in the thru line (0 dB).
With positive voltage applied
to the common pin, the state
(attenuator card or thru line) of
a particular section is driven by
connecting its attenuator card pin
or thru pin to a negative voltage or
ground. Figure 3 defines the pin
assignments and wire color code
for the 11764-60001/60002/60003
drive cables. Table 1 is a solenoid
drive pin and attenuation guide.
Table 2 (on page 5) defines
recommended attenuation section
activation.
As a section is switched, the
internal contacts of the activated
coil open, thus shutting off current
flows. At the same time, the internal
contacts for the other coil close so
that it can be activated when
desired. Figure 1 shows a section
that has been switched to the
attenuator card position (note the
closed thru line coil contact). The
switching is “break-before-make”
type, thus momentary interruption
of the RF signal occurs at switching.
3
Figure 1: Driver and indicator circuits for one
section of an Agilent 8494/5/6/7
Typical
external
driver
RF input
Attenuation
card
To next
section
RF to
next section
of output
Attenuator card
drive pin
(e.g., pin 2)
Internal
coil contacts
Thru line
pin
(e.g., pin 1)
Figure 2: Section electrical diagram
Although all sections can be
switched simultaneously, the
attenuator driver must not allow
both pins of the same section (e.g.
Section 1, pins 1 and 2) to be
activated concurrently, or else
that section would cycle rapidly.
All terminals are “floating,” so
bipolar or unipolar power supplies
can be used.
Typical driver circuit
Figure 1 shows an economical
TTL compatibility driver circuit for
a single attenuation section that
utilizes an IC relay driver and an
inverter. A TTL “HI” input to the
driver switches in the attenuator
card, while a “LO” will activate
the thru line for that section. This
provides a complimentary driver for
the section that assures that only
one solenoid of the pair is activated
at a time.
Switch position can be indicated
remotely by utilizing the open and
closed states of the internal coil
contacts. Connected at A and B in
Figure 1 are two indicator circuits,
one providing a TTL output and
one that activates an LED. These
circuits will output a TTL “HI” (LED
lamp “ON”) if the attenuator card
is in the RF circuit, and will output
a TTL “LO” (LED lamp “OFF”) if
the thru line is in the RF circuit.
Since current is drawn through the
coil for these circuits, inadvertent
switching is prevented by limiting
the current to 5 mA.
Agilent Technologies assumes no
responsibility for the use of any
circuits described herein and makes
no representation or warranties,
express or implied, that such
circuits are free from patent
infringement.
Switch driver circuit
LED indicator circuit
▲
▲
TTL input
+5V
Inverter
IC relay driver
(DM7404N*)
*Fairchild Semiconductor
part numbers, also supplied
by other vendors:
NOTE: Additional circuit
design information may
be required from the
component manufacturers.
+5V
LED
5082-4880 (DM7406N*)
(DS75451N*)
Driver
TTL indicator circuit
TTL output
Inverter
(DM7404N*)
+24V
0.62K0.13K
4.22K
Drive
cable
A
B
4.22K
D
0.62K
Attenuator section
Thru line
drive pin
Internal
coil contacts
RF
connector
drive pin
RF in
Thru line
Attenuation card
To next section
RF to next
section
or output
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