Microwave Attenuator Series 347

Application Notes for Microwave Attenuators

The Series 347 digitally controlled PIN diode attenuators offer essentially phase free operation over a wide dynamic range in multi-octave frequency bands between 2 and 18 GHz. The attenuators utilize a unique double balanced arrangement of diodes and quadrature couplers to achieve the phase independent attenuation characteristic. Excellent temperature stability is maintained by employing a self-compensating biasing scheme. See Fig. 1.

Series 347 attenuator RF schematic diagram

Low Phase Shift
Frequency range: 2-18 GHz
Non-reflective
Attenuation range: to 45 dB
LSB: 0.125 dB
High Speed

TYPICAL PERFORMANCE

series 347 attenuation vs frequency performance diagram series 347 phase vs frequency performance diagram

PERFORMANCE CHARACTERISTICS

MODEL

3472

3474

3478

Frequency Range (GHz)

2-6

4-11

6-18

Mean Attenuation Range

32 dB

Insertion Loss (Max)

4 dB

5 dB

7 dB

VSWR (Max)

2.0

3.0

Accuracy of Attenuation

± 0.5 dB

Amplitude Flatness 0 to 20 dB
> 20 to 32 dB

± 0.4 dB
± 0.6 dB

± 0.4 dB
± 0.8 dB

± 0.8 dB⁽¹⁾
± 1.3 dB⁽¹⁾

Monotonicity

Guaranteed

Phase Shift 0 to 20 dB
> 20 to 32 dB

± 4 °
± 8 °

± 5 °
± 10 °

On Time, Off Time

350 ns

Temperature Coefficient

.02 dB/°C

Max. RF Power Input (Operating)

100 mW

Max. RF Power Input (Survival)

0.5 W

Harmonic Distortion @ Pin = +10 dBm

-40 dBc

-50 dBc

Control

8 bit TTL, 0.125 dB LSB

Control Input Impedance

@ Logic “0” (- 0.3 to +0.8 V) 500 µA max.
@ Logic 1″ (+2.0 to +5.0 V), 100 µA max.

Logic Input

Logic “0” = Bit OFF Logic “1” = Bit ON

Power Supply Requirements

+5V ± 5% @ 325 mA
+15V ± 5% @ 15 mA
-15V ± 5% @ 70 mA

SPECIFICATIONS with EXTENDED RANGE OPTION (OPTION 45)

Mean Attenuation Range

45 dB

Accuracy of Attenuation

± 1.0 dB

Amplitude Flatness

0 to 20 dB
> 20 to 32 dB
> 32 dB

± 0.4 dB
± 0.6 dB
± 1.5 dB

± 0.4 dB
± 0.8 dB
± 1.5 dB

± 0.8 dB⁽¹⁾
± 1.3 dB⁽¹⁾
± 2.0 dB

Phase Variation

0 to 20 dB
> 20 to 32 dB
> 32 dB

± 4 °
± 8 °
± 15 °

± 4 °
± 8 °
± 20 °

± 5 °
± 10 °
± 30 °

Control

8 bit TTL, 0.176 dB LSB

(1) Except from 8-18 GHz, flatness is ± 0.5 dB up to 20 dB, ± 1.0 dB up to 32 dB.

.
OPTION (G09) ENVIRONMENTAL RATINGS
Operating Temperature Range………………..	-54°C to + 110°C
Non-Operating Temperature Range…………	-65°C to + 125°C
Humidity…………………………………………….	MIL-STD-202F, Method 103B, Cond. B (96 hrs. at 95%)
Shock………………………………………………..	MIL-STD-202F, Method 213B, Cond. B (75G, 6 msec)
Vibration……………………………………………	MIL-STD-202F, Method 204D, Cond. B (.06″ double amplitude or 15G, whichever is less)
Altitude……………………………………………..	MIL-STD-202F, Method 105C, Cond. B (50,000 ft.)
Temp. Cycling………………………………………	MIL-STD-202F, Method 107D, Cond. A, 5 cycles

AVAILABLE OPTIONS

Option No.

Description

Two SMA male RF connectors

One SMA male (J1) and one SMA female (J2) RF connectors

Extended attenuation range to 45 dB

± 12V operation

G09

Guaranteed to meet Environmental Ratings

G12

RoHS & REACH Compliant

G18

REACH Compliant

ACCESSORY FURNISHED
Mating power/logic connector

J3 PIN FUNCTIONS
PIN NO.	BINARY	OPTION 45
1	-15V	-15V
2	+15V	+15V
3	Do Not Connect	Do Not Connect
4	0.125dB(LSB)	0.18 dB
5	0.5 dB	0.70 dB
6	4 dB	5.62 dB
7	16 dB (MSB)	22.5 dB
8	8 dB	11.25 dB
9	GROUND	GROUND
10	NOT USED	NOT USED
11	2 dB	2.81 dB
12	0.25 dB	0.35 dB
13	1 dB	1.41 dB
14	NOT USED	NOT USED
15	+5V	+5V

DIMENSIONS AND WEIGHT

Dimensions are stated in inches (mm). Tolerances,
unless otherwise indicated: .XX ±.02; .XXX ±.008

MODEL

3472

2.5 (63,5)

2.26 (57,4)

2.28 (57,9)

0.22 (5,6)

1.25 (31,7)

3474

2.0 (50,8)

1.76 (44,7)

2.43 (61.7)

0.18 (4,6)

1.0 (25,4)

3478