Excellent repeatability
High accuracy
Excellent reliability, long life
Features and description
• DC to 26.5 GHz, DC to 40 GHz
frequency coverage
• Optional calibration data
• 0 to 11 dB, 70 dB, 90 dB
• 1 dB steps, 10 dB steps
• Excellent repeatability
• High accuracy
• Excellent reliability, long life
• Exceptionally low insertion loss
These attenuators offer repeatability
of better than 0.03 dB and excellent
life (greater than 5 million switching
cycles per section).
This family of programmable step
attenuators offers coaxial measurements to 26.5 GHz (K models) or to
40 GHz (L models), in a compact,
rugged design. The first model in this
family is the Agilent Technologies
84906K/L, which offers outstanding
performance with an attenuation
range of 0 to 90 dB in 10 dB steps.
Other models include the Agilent
84904K/L, with 0 to 11 dB of attenuation in 1 dB steps, and the Agilent
84907K/L, with 0 to 70 dB of attenuation in 10 dB steps.
This latest design evolution sets new
standards for size and performance.
High attenuation accuracy and low
SWR are achieved through the use of
miniature thin-film attenuation cards
composed of high-stability tantalum
nitride film on a sapphire substrate.
Insertion loss performance is out-
standing, with less than 2 dB of loss
at 26.5 GHz and only 2.4 dB at 40 GHz
(figure 1). The compact size of the
units, 35% smaller than the 8495/7
(26.5 GHz) family, allows for easy
integration into instruments and ATE
systems.
This family of step attenuators offers
three connector types. For operation
to 40 GHz, the 84904/6/7L models
offer either the 2.4 mm connector,
which is recommended for top performance and for rugged and repeatable connections, or the 2.92 mm connector, which is compatible with SMA
and 3.5 mm connectors but is more
delicate. For operation to 26.5 GHz,
the 84904/6/7K models offer the
3.5 mm connector. This connector is
compatible with SMA and 2.92 connectors, but is more rugged. Each
model in the 84904/6/7K and L family
comes with two female connectors
(standard) or may be ordered with
one female and one male connector
for easy insertion into a microwave
chain or to combine the 1 dB step
Agilent 84904, 6, 7K/L
Programmable Step Attenuators
Data Sheet
Figure 1. Insertion loss
4
Insertion
Loss
(dB)
(.8)
(.6)
3
2
1
0
84904/6K
(1.9)
10 20
Frequency (GHz)
(1.4)
84907K
30
84904/6L
(2.4)
(1.8)
84907L
40
2
84904 with a 10 dB step 84906 or
84907 to cover an attenuation range
of 121 dB or 81 dB in 1 dB steps.
Individual calibration data reports of
attenuation and SWR are available.
This data, measured with an Agilent
automatic network analyzer, can be
ordered as Option 8490xx-890.
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
milli-seconds, including 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 (figure 3). Solenoids
are available in either 24 volt (standard, Option 8490xx-024), 15 volt
(Option 8490xx-015), and 5 volt
(Option 8490xx-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 with DIP-type connectors
that is compatible with standard 14pin DIP IC sockets (11764-60002 or
11764-60003, respectively). Alternatively, a 1524 mm (5 foot) cable with
free wires for direct soldering (11764-
60001), 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 systems (11764-60004),
may be ordered.
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).
Figure 2. Section electrical diagram
With positive voltage applied to the
common pin, the state (attenuator
card or thru line) of a particular section is determined by connecting its
attenuator card pin or thru pin to a
negative voltage or ground. Figure 4
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 4) defines recommended attenuator section activation.
As a section is switched, the internal
contacts of the activated coil open,
thus shutting off current f low. At the
same time, the internal contacts for
the other coil close so that it can be
activated when desired. Figure 3
shows a section that has been
switched to the attenuator card position (note the closed thru line coil
contact). The switching is “breakbefore-make” type, thus a momentary
interruption of the RF signal occurs
at switching.
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.
Figure 3. Driver and indicator circuits for one section of an Agilent 8494/5/6/7
RF Connector
Drive Pin
Typical
External
Driver
RF Input
(e.g., pin 6)
Thru Line
Pin
(e.g., pin 5)
Attenuation
Card
Internal
Coil Contacts
To next
Section
next Section
of Output
RF to
LED Indicator Circuit
+5V
LED
5082-4880 (DM7406N*)
Switch Driver Circuit
TTL Input
+5V
Inverter
IC Relay Driver
(DM7404N*)
*National Semiconductor
part numbers, also supplied
by other vendors:
NOTE: Additional circuit
design information may
be required from the
component manufacturers.
(DS75451N*)
▲
▲
Driver
+24V
TTL Indicator Circuit
TTL Output
Inverter
(DM7404N*)
D
A
B
0.620.13
4.22
4.22K
0.62K
Attenuator Section
Drive
Cable
RF In
Thru Line
Drive Pin
Internal
Coil Contacts
RF
Connector
Drive Pin
Thru Line
Attenuation Card
To next Section
RF to next
Section
or Output
3
Typical driver circuit
Figure 3 shows an economical TTL
compatibility driver circuit for a single attenuation section which utilizes
and IC relay driver and an inverter. A
TTL “HI” input to the driver switches
in the attenuation card, while a “LO”
will activate the thru line for that section. This provides a complimentary
driver for the section which assures
that only one solenoid of the pair is
activated at a time. Diode protection
is required to protect the IC from the
solenoid voltage flyback.
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 3 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 attenuation 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.
Drive cables
11764-60001 10 pin DIP to 60” long
ribbon cable
11764-60002 10 pin DIP to 14 pin DIP,
8” long
11764-60003 10 pin DIP to 14 pin DIP,
16” long
11764-60004 10 pin DIP to 12 pin Viking
connector, 60” long. Used
with 11713A driver
11764-60006 10 pin DIP to (4) 4 pin BERG
connectors, 30” long. Used
with 87130A or 70611A driver
Attenuator
Figure 4. Attenuator switching pinout
Section: Section 1 Section 2 Section3 Section 4
Thru Attn Thru Attn Thru Attn Thru Attn
Model Number Line Card Line Card Line Card Line Card
84906K/L
Attenuation (dB) 0 10 0 20 0 30 0 30
Actuating pin 1 2 5 8 4 9 6 7
11764-60004 plug
Pin number 5 6 7 8 9 10 11 12
11764-60002/60003 flat
Header pin number 13 2 11 5 3 9 4 10
84907K/L
Attenuation (dB) 0 10 0 20 0 40
Actuating pin 1 2 5 8 4 9
11764-60004 plug
Pin number 5 6 7 8 9 10
11764-60002/60003 flat
Header pin number 13 2 11 5 3 9
84904K/L
Attenuation (dB) 0 1 0 2 0 4 0 4
Actuating pin 1 2 5 8 4 9 6 7
11764-60004 plug
Pin number 5 6 7 8 9 10 11 12
11764-60002/60003 flat
Header pin number 13 2 11 5 3 9 4 10
Pin 10 is +24 volts
Table 1. Solenoid pin and attenuation guide
DIP plug
12
910
RF connector
11764-60002/3 header
114
213
312
411
510
69
78
11764-60001/2/3
14 pin header colors
114
213
Red
Yellow
312
411
Blue
510
Gray
6 9
Black
7 8
Brown
Orange
Green
Violet
White
11764-60001/2/3 wire colors
1. Brown 2. Red
3. Orange 4. Yellow
5. Green 6. Blue
7. Violet 8. Gray
9. White 10. Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Gray
White
Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Gray
hite
W
Black
14
1
8
7
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