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2–18 GHz
HIGH SPEED
SWITCHED-BIT
ATTENUATORS
FEATURES
·
·
·
·
·
Very High Speed
Precise Attenuation over Frequency
Band
Small Package Size
Low Insertion Loss
Hermetically Sealed
Wide-Band EW Systems
Radar and Phased Array Systems
Wide-Band Instruments and Test
Systems (ATE)
APPLICATIONS
·
·
·
OPTIONS AVAILABLE BASED ON
STANDARD DESIGNS
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·
Different Attenuation Range
Performance Optimized over a
Narrower Bandwidth
DESCRIPTION
These miniature, high speed digitally controlled switched-
bit attenuators are designed for operation over
multi-octave bandwidths. Attenuation levels are guaran-
teed to be monotonic and selectable using standard TTL
logic circuitry. All models are hermetically sealed and are
specified to operate over the full temperature range. All
attenuators are equipped with removeable RF connectors
and are suitable for drop-in applications.
system requirements can only be met by using a look-up
table to correct for these errors.
DCAs provide very precise attenuation levels in digital (bi-
nary) increments. They have extremely fast switching
speeds compared to VVAs – typically ten to twenty times
faster. These switched bit attenuators combine one or
more tandem pairs of SPDT PIN diode switches with a
zero loss connection between one pair of outputs and a
fixed attenuator inserted in the other. The PIN diodes are
simply switched between their forward and reverse
states, rather than being used as variable attenuators.
Very high speed PIN diodes and control circuitry are used
to operate all the bits in parallel.
The major disadvantages of DCAs versus VVAs are: the
minimum practical attenuation level, higher cost due to
more complex circuits, somewhat higher insertion loss,
and the potential for video leakage due to the high speed
switches. The smallest practical Least Significant Bit
(LSB) is about 0.5 dB. Video filters can often be incorpo-
rated into the DCA to satisfy specific leakage requirements.
TOC
DIGITALLY CONTROLLED
ATTENUATORS (DCAs)
versus VOLTAGE VARIABLE
ATTENUATORS (VVAs)
A VVA allows the user to select any value within its rated
attenuation range – the user has full analog control. Most
VVAs operate by changing the bias current of the series
and shunt PIN diodes that form attenuator pads. This de-
sign approach leads to significant errors in attenuation
level over the operating bandwidth. The most demanding
484
USA TEL: (1) 631 231-1700 • INT’L TEL: (1) 631 231-1390 • FAX (1) 631 231-1711
E-MAIL: nardaeast@L-3COM.com • www.nardamicrowave.com
Wireless
Products
Electromechanical
RF Switches
Passive
Components
Active
Components
RF Radiation
Safety Products
Power
Meters/Monitors
Main
Menu
Control Products
ENVIRONMENTAL SPECIFICATIONS
TEMPERATURE
Operating . . . . . . . . . . . . . . . . -65°C to +125°C
Storage. . . . . . . . . . . . . . . . . . -54°C to +95°C
HUMIDITY
Per MIL-STD-202F, method 103B, condition B
(96 hours at 95% R.H.)
SHOCK
Per MIL-STD-202F, method 213B, condition B
(75G, 6 msec)
ALTITUDE
Per MIL-STD-202F, method 105C, condition B
(50,000 feet)
VIBRATION
Per MIL-STD-202F, method 204D, condition B
(.06" double amplitude or 15G, whichever is less).
THERMAL SHOCK
Per MIL-STD-202F, method 107D, condition A
(5 cycles)
OUTLINE DRAWINGS
TOC
1
2
3
Dimensions in parentheses are in millimeters and for reference only.
4
488
USA TEL: (1) 631 231-1700 • INT’L TEL: (1) 631 231-1390 • FAX (1) 631 231-1711
E-MAIL: nardaeast@L-3COM.com • www.nardamicrowave.com
Industrial Control Electronics
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