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

Abstract

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

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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

Frequency27.5 to 28.5 GHz
Reference Insertion Loss0 dB typical over band
Attenuation1 dB LSB steps to 62 dB
Rise Time/Fall TimeLess than 70 nano Seconds
DC Bias[email protected], +12 Volts maximum
TTL Control+5V Maximum for TTL High
Input 1 dB Compression Point20 dBm
Maximum RF Input Power (C.W.)25 dBm maximum
Attenuation Accuracy1 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 PortWR-28 Waveguide with UG-599/U
Output PortWR-28 Waveguide with UG-599/U
TTL PortFeed Thru Pins
DC Bias PinFeed Thru Pins
MaterialAluminum
FinishGold Plated
Size1.5”X1.5”X1.5”
Weight2 Ounces

D. Truth Table

P5

32 dB

P4

16 dB

P3

8 dB

P2

4 dB

P1

2 dB

P0

1 dB

Attenuation State
HighHighHighHighHighHighReference Insertion Loss
HighHighHighHighHighLow1 dB
HighHighHighHighLowHigh2 dB
HighHighHighLowHighHigh4 dB
HighHighLowHighHighHigh8 dB
HighLowHighHighHighHigh16 dB
HighLowLowLowLowLow31 dB
LowLowLowLowLowLow62 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

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

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

Email: [email protected]

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