28 GHz Bidirectional 0 to 62 dB Voltage Controlled Variable Digital Attenuator for 5G Application


Digitally controlled attenuators are the key components in communication, radar, instrumentation, and automatic test systems. Broad bandwidth, high dynamic attenuation range, low insertion loss, high control resolution and fast control speed are key considerations in nearly all applications.

This paper shows the implementation, features, operation, and 5 G application of Bidirectional voltage variable digital attenuator with 0-62 dB attenuation range and how it is used to test 28 GHz 5 G signal.

Published by:
Lokesh Saggam, Shashi Saggam, Engineering Department, Millimeter Wave Products Inc., Saint Petersburg, Florida, [email protected], [email protected]

Contact Info:
2007 Gandy Blvd N
Suite 1310
St. Petersburg, FL 33702

Tel: 727-563-0034
Fax: 727-563-0031

I. Introduction

The attenuator is one of the key components of modern communications. Therefore, the design of attenuator with high resolution, large attenuation, low insertion loss and low phase variation has great value, and very broad application prospects. 28 GHz Bidirectional 0-60 dB Voltage Controlled Digital Attenuator is a digital attenuator with attenuation range of 0-60 dB. The attenuation level is controlled by TTL signal. It comes in very small size and works in both directions. The RF signal can be transmitted and received simultaneously. The attenuation is varied between 0 to 62 dB range in 1 dB steps.

II. Features

A. Bidirectional
The attenuator is bidirectional, and signal can be transmitted in any directional simultaneously. This feature is useful when the signal has to be transmitted and received simultaneously during 5G radio filed testing.

B. Digital Attenuator
The attenuator is 6 bit digital attenuator with 1dB LSB steps.

C. Small Size
The size is very small compared to programmable rotary vane attenuators and best for applications where the space is limited.

D. Excellent Attenuation Accuracy
The attenuator has excellent accuracy with +/-1 dB typical bit error.

E. Switching Characteristics
The proposed attenuator is much faster than programmable rotary vane attenuators. Rise and Fall time is 70 nano Seconds.

F. Wide Attenuation Range
The attenuator provides 0 to 62 dB attenuation range.

G. Insertion Loss
This attenuator provides 0 dB insertion Loss.

III. Specifications

A. Electrical Specifications

Frequency 27.5 to 28.5 GHz
Reference Insertion Loss 0 dB typical over band
Attenuation 1 dB LSB steps to 62 dB
Rise Time/Fall Time Less than 70 nano Seconds
DC Bias [email protected], +12 Volts maximum
TTL Control +5V Maximum for TTL High
Input 1 dB Compression Point 20 dBm
Maximum RF Input Power (C.W.) 25 dBm maximum
Attenuation Accuracy 1 dB typ. Bit Error

B. Operating Precautions

a) Case Temperature of the digital Attenuator should never exceed above +60 degree Celsius.
b) Reverse Biasing will destroy the digital attenuator.
c) Power on Sequence: Apply +8 Volts and then TTL signals per attenuation.
d) Power off Sequence: Always turn off TTL signals before +8 V supply.

C. Physical Dimensions

Input Port WR-28 Waveguide with UG-599/U
Output Port WR-28 Waveguide with UG-599/U
TTL Port Feed Thru Pins
DC Bias Pin Feed Thru Pins
Material Aluminum
Finish Gold Plated
Size 1.5”X1.5”X1.5”
Weight 2 Ounces

D. Truth Table


32 dB


16 dB


8 dB


4 dB


2 dB


1 dB

Attenuation State
High High High High High High Reference Insertion Loss
High High High High High Low 1 dB
High High High High Low High 2 dB
High High High Low High High 4 dB
High High Low High High High 8 dB
High Low High High High High 16 dB
High Low Low Low Low Low 31 dB
Low Low Low Low Low Low 62 dB

III. Implementation

Outline Drawing

IV. Application

• Fiber Optics & Broadband Telecom
• Microwave Radio & VSAT
• Military Radios, Radar & ECM
• Space Applications
• Sensors
• Test & Measurement Equipment
• 5G Radio Field Test

standard gain horn antenna page

How to Order & Custom Products

As the manufacturing source, we have top sales engineers ready to answer all your questions and quote you on product needs. You’ll find our prices are some of the best since we manufacture all our millimeter wave products in house.

Have a custom job or unique need? No problem! Contact us so we can work on solutions to meet your needs.

2007 Gandy Blvd N
Suite 1310
St. Petersburg, FL 33702

Tel: 727-563-0034
Fax: 727-563-0031

Email: [email protected]