Series 349 and 349H Octave-Band 11 Bit Digital PIN Diode Attenuators

Application Notes for Microwave Attenuators

The Series 349 and 349H programmable attenuators provide greater than octave-band performance and wide programming flexibility in compact rugged packages. Attenuation ranges up to 80 dB are available with attenuation increments as low as 0.03 dB.

Each Series 349 and 349H unit is
an integrated assembly of a balanced PIN diode attenuator and a driver
circuit.  A standard version of the attenuator has a driver circuit
consisting of a PROM, a D/A converter and a current-to-voltage converter. See
Figure 1.  The G10 glitch-free option (see Available Options list below)
driver circuit is based on an FPGA and a faster D/A converter designed for
smooth glitch-less transitions while switching between attenuation levels. Both
versions, the standard and the G10 option, provide a high degree of accuracy
and repeatability and preserves the inherent monotonicity of the
attenuator.  Option G10 is recommended for new designs.

The maximum programmable attenuation range in every band except the 8.0–18.0 GHz frequency range is 80 dB. Attenuators limited in range to 64 dB exhibit switching times less than 500 ns while the 80 dB units switch in less
than 2 µsec.

If even faster switching of 64 dB units is required,
GMC offers its Series 349H attenuators. These units switch in less
than 300 ns with essentially the same performance specifications as the 64 dB Series 349 units.
All the attenuators
are available with either a strobe/ latch or a non-linear current or voltage controlled attenuation capability. Refer to the Available Options table and the Notes following the Pin Functions table.

• Absorptive
• 64 or 80 dB range
• 0.03 dB resolution
• Binary or BCD programming
• Guaranteed monotonicity
• Frequency range: 0.75 to 18GHz

 

PERFORMANCE CHARACTERISTICS: SERIES 349

PERFORMANCE CHARACTERISTICS: SERIES 349H

Mean Attenuation Range
	349(X), 349(X)H-64………………………………	64 dB
	349(X)-80…………………………………………….	80 dB
Accuracy of Attenuation
	0 to 30dB………………………………………………	± 0.5 dB
	> 30 to 50 dB…………………………………………	± 1.0 dB
	> 50 to 64 dB…………………………………………	± 1.5 dB
	> 64 to 80 dB…………………………………………	± 2.0 dB
Monotonicity…………………………………………………………		Guaranteed
Phase Shift……………………………………………………………		See Application Notes
Temperature Coefficient…………………………………………		± 0.025 dB/°C
Power Handling Capability without Performance Degradation
	3491, 3492H thru 3498H…………………	10 mW cw or peak
	3491H…………………………………………….	1 mW cw or peak
	All other units………………………………….	100 mW cw or peak
Survival Power
	from -40°C to +25°C;    (see Figure 2 for Higher Temperatures)……..	1W average, 25W peak (1 µsec max pulse width)
Switching Time
	349(X)H-64……………………………………….	300 ns max.
	349(X)-64…………………………………………	550 ns max.
	349(X)-80…………………………………………	2 μsec max.
Programming………………………………………………………..		Positive true binary (standard) or BCD (Option 1). For complementary code, specify Option 2.
	Minimum Attenuation Step(5)………………………	0.25 dB
	Binary Units
	349(X)-64, 349(X)H-64……………………..	0.03 dB
	349(X)-80………………………………………..	0.04 dB
	BCD Units………………………………………………	0.10 dB
Logic Input
	Logic “0” (Bit OFF)…………………………………..	-0.3 to +0.8V
	Logic “1” (Bit ON)…………………………………….	+2.0 to +5.0V
	Logic Input Sink Current………………………….	0.3 mA max
	Logic Input Source Current………………………	3 µA max
Analog Input (6)
	349(X)-64, 349(X)H-64…………………………..	0 to 6.4V(7)
	349(X)-80…………..…………………………………	0 to 8V(8)
	Input Resistance……………………………………..	10K ± 20% Ohms
Power Supply Requirements…………………………………..		+12 to +15V, 120mA
		-12 to -15V, 50mA
Power Supply Requirements……………………………………		1. Less than 0.1 dB/volt change in either supply
		2. Prior to applying the supply voltages, all the command bits (including the Latch bit) should be set to “0” logical level
NOTES

(1) Applicable only to 80 dB versions.
(2) Specifications for the extended frequency ranges are typical.
(3) Except from 16-18 GHz where insertion loss is 4.2 dB max. and VSWR is 2.2.
(4) Flatness specification at 64 dB level is ±0.2 dB higher than at 60 dB. 
(5) The Series 349 attenuators are 11-bit digital attenuators. In order to use this device with a lesser number of bits (lower resolution), the user may simply ground the logic pins for the lowest order unused bits. For example, a Series 349 unit operated as an 8-bit unit would have Pin 15, Pin 1 and Pin 2 connected to ground. All other parameters remain unchanged.
(6) Switching speed for analog input is 100 µsec. typical. With Option G06 it is not greater than with digital input.
(7)  For average attenuation of 64 dB the analog voltage is in the range of 4 to 8 V.
(8)  For average attenuation of 80 dB the analog voltage is in the range of 6 to 10 V.

OPTION (G09) ENVIRONMENTAL RATINGS

 DIMENSIONS AND WEIGHT

Weight: 4 oz. (113 gr) approx. Dimensions are stated in inches (mm).  Tolerances, unless otherwise indicated: .XX ±.02; .XXX ±.008

 NOTES

(1) The Series 349 attenuators are 11-bit digital attenuators. In order to use this device with a lesser number of bits (lower resolution), the user may simply ground the logic pins for the lowest order unused bits. For example, a Series 349 unit operated as an 8-bit unit would have Pin 15, Pin 1 and Pin 2 connected to ground. All other parameters remain unchanged.
(2) Normally supplied as an Analog input. Leave pin open if analog input is not used. Optionally available as a strobe latch function for input data.
(3) Pin 3 is available to apply a current or voltage to control the attenuator in a non-linear fashion.
(4) lt is recommended that when operating the Series 349/H Attenuators with the Strobe/Latch Option -4 feature, the digital control inputs should be in place, with the Latch set to a low “0” level, before the Attenuator is powered up.
(5) For Model 3494-80-D69, J3 PIN 13 is +15V±5% and PIN 14 is -5V±5%.