Microwave Attenuator: Series 348 and 348H

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Application Notes for Microwave Attenuators

The Series 348 and 348H Digitally Programmable Attenuators provide greater than octave band performance in small hermetic packages ideally suitedfor high reliability applications. The Series 348 offers moderate power handling capability (100 mW) at switching speeds less than 500 nsec while the 348H Series offers 200 nsec switching speed at lower poweAttenuation of all units is 60 dB with monotonic 0.25 dB step resolution.

The attenuator is an integrated assembly of a sealed RF Microwave Integrated Circuit assembly and a sealed hybrid driver. Attenuation is controlled via a miniature 14 pin connector. See Fig. 1.

Although these units are primarily intended for use as digital attenuators, they can also be used as analog (voltage driven) attenuators or as combination analog/digital attenuators. (See note 4 below)

 

  • 2 to 18 GHz
  • Digital/Analog
  • 8 Bit TTL
  • Hermetically sealed
  • Miniature

 

Microwave attenuator series 348 - Kratos General Microwave

                                                  Model 3484

 

 

Series 348 and 348H attenuator block diagramModel 3488 typical phase vs attenuation and frequency
Model 3250A attenuator survival power derating factor  

 

PERFORMANCE CHARACTERISTICS
 
MODEL FREQUENCY RANGE (GHz) MAX. INSERTION LOSS (dB) MAX. VSWR FLATNESS (± dB)
AT MEAN ATTENUATION LEVELS UP TO
10 dB 20 dB 40 dB 60 dB
3482/H* 2.0 - 4.0 1.8 1.5 0.5 1.0 1.5 1.6
1.5 - 4.5(1) 1.9 2.0 0.7 1.6 3.0 3.5
3483*/H* 2.6 - 5.2 2.0 1.6 0.5 1.0 1.5 1.6
1.95 - 5.85(1) 2.1 2.1 0.7 1.6 3.0 3.5
3484/H 4.0 - 8.0 2.4 1.7 0.5 1.0 1.5 1.6
3.0 - 9.0(1) 2.5 2.2 0.7 1.6 3.0 3.5
3486/H 6.0 - 12.0 2.7 1.8 0.7 1.0 1.5 1.6
4.5 - 13.5(1) 2.8 2.2 0.9 1.6 3.0 3.5
3488/H 8.0 - 18.0 3.0(2) 1.8(3) 0.7 1.0 1.5 1.6
6.0 - 18.0(1) 3.0(2) 1.8(3) 0.9 1.6 3.0 3.5

 * Special-order product. Consult factory before ordering. 

(1) Specifications for the extended frequency ranges are typical.
(2) For 3488, 4.0 dB from 16-18 GHz. For 3488H, 3.5 dB from 12-16 GHz and 4.0 dB from 16-18 GHz.
(3) VSWR is 2.0 from 16-18 GHz.

Mean Attenuation Range....................................
60 dB
Accuracy of Attenuation
   0 to 30dB............................... ± 0.5 dB
   > 30 to 50 dB......................... ± 1.0 dB
   > 50 to 60 dB......................... ± 1.5 dB
Monotonicity.........................
Guaranteed
Phase Shift.............................
See Fig. 2
Temperature Coefficient........
± 0.02 dB/ °C
Power Handling Capability
   Without Performance
      Degradation
...............
......

(348) 100 mW cw or peak
(348H) 10 mW cw or peak

Survival Power
   (from -65°C to +25°C;
   see Figure 3 for
   Higher Temperatures).............


1W average, 25W peak
Switching Time...................... (348) 500 nsec max
(348H) 200 nsec max
Programming: 8 Bit TTL........
Positive True binary
Minimum Attenuation Step... 0.25 dB
Logic Input
   Logic "0".............................. -0.3 to +0.8V
   Logic "1".............................. +2.0 to +5.0V
   Logic Input Current............... 10 µA max
Analog Input Characteristics
   Range................................... 0 to 6V
   Transfer Function.................. 10 dB/V
   Input Resistance................... 6 kohms
Power Supply
   Requirements
......................

+12 to +15V, 120mA
  -12 to -15V, 50 mA
   
OPTION (G09) ENVIRONMENTAL RATINGS
Operating Temperature
   Range....................... -54°C to +110°C
Non-Operating Temperature
   Range....................... -65°C to +125°C
 
ACCESSORY FURNISHED
Mating power/logic connector
 
AVAILABLE OPTIONS
Option No. Description
7
Two SMA male RF connectors
10
One SMA male(J1) and one SMA female (J2) RF connector
49*

High Rel screening (see Table 1 below for further information))

 G09 Guaranteed to meet Environmental Ratings
G12 RoHS Compliant
G16 RoHS Plus REACH Compliant

Table 1. Option 49 High Rel Screening 

Kratos General Microwave’s hermetically-sealed products utilize rugged construction techniques and hermetic sealing to meet stringent military requirements for shock, vibration, temperature, altitude, humidity, and salt atmosphere. All hermetically-sealed parts may be ordered, if desired, with 100% screening in accord with the following MIL-STD 883:

TEST METHOD CONDITION
Internal Visual
2017 --
Temperature Cycle
1010 B
Mechanical Shock
2002
A
Burn-In (at110°C)
1015
--
Leak
1014
A1 & A2
DIMENSIONS AND WEIGHT
 
  Series 348 and 348H attenuator dimensions and weight diagram
 
 SERIES 348/H
wt: 2.4 oz. (68 gr) approx.
 
Dimensional Tolerances, unless otherwise indicated: .XX ±.02; .XXX ±.008
 
 J3 POWER/LOGIC CONNECTIONS
PIN 
FUNCTIONS
 A  Digital/Power GND
 B  Logic Control (Note 2)
 C  –12 to –15V
 D  0.25 dB (LSB)
 E  0.5 dB
 F  1 dB
 H  4 dB
 J  2 dB
 K  16 dB
 L  32 dB (MSB)
 M  +12 to +15V
 N  8 dB
 P  GND
 R  Analog Input (Notes 3&4)
 
 NOTES
1. All unused logic inputs must be grounded.
2. For normal TTL programming control, PIN B must be grounded or at Logic 0. Application of Logic 1 to PIN B overrides the digital input and sets the unit to insertion loss. To interface with other logic families (e.g., CMOS, MTL, NMOS, etc.) contact factory.
3. If Analog input is not to be used, then connect PIN R to PIN P.
4. To use the unit as a voltage controlled attenuator, apply a control voltage of 0 to +6V at PIN R. The slope of attenuation will be nominally 10 dB/V. For a non-zero source resistance (RO) of up to 500 ohms, the attenuation error is approximately –.0017 • RO • VIN dB and the slope will decrease by approximately 0.17 dB/V per 100 ohms of source resistance.
Using the 348/H Series attenuator as both a digital and analog control attenuator, the total attenuation ATT = 10 • VIN + programmed digital attenuation. The maximum attainable mean attenuation is 60 dB.