Case ID: M07-090P^

Published: 2020-02-26 11:13:50

Last Updated: 1661889270


Inventor(s)

Hang Song
James Aberle
Bertan Bakkaloglu

Technology categories

Physical ScienceWireless & Networking

Licensing Contacts

Shen Yan
Director of Intellectual Property - PS
[email protected]

Analog Return Loss Detection and Matching State Searching Circuit for Automatic Antenna Impedance Tuning System

Before converting detected power levels to the digital
domain, conventional antenna tuning systems couple incident and reflected powers
through a three-line directional coupler in addition to two RF power detectors.
Replacing these conventional antenna tuning systems with the automatic antenna
matching techniques and devices employed at lower radio frequencies can greatly
improve commercial wireless and military communications.

Researchers at ASU have invented a system that effectively
utilizes these automatic antenna matching techniques and devices and have
reduced the system to practice using discrete components on several printed
circuit boards. Specifically, this system employs an analog subtractor by
finding the difference between the outputs of two logarithmic power detectors to
compute return loss. While the antenna tuning system searches for the optimum
matching state, it stores the initial value of return loss and the impedance
synthesizer state in an analog sample and hold (S/H) and digital register,
respectively. Comparing each new return loss value to the old, the system stores
whichever value is larger as well as the associated matching state until finding
the optimum matching state. As a result, this system requires no analog to
digital convertors (ADC) and consequently, eliminates the cost of high accuracy
ADCs, which require moderate power and occupy significant silicon space.

Potential Applications

An analog return loss detection system offers great benefit
to the emerging market of software defined radio (SDR), which is expected to
grow rapidly in the future.


  • Software Defined Radio architectures
  • Current automatic antenna tuning schemes

Benefits and Advantages


  • Accuracy ? By eliminating the ADCs, the quantization
    accuracy of the ADCs does not limit the accuracy of the circuit.

  • Reduced Clock Cycle ? Impedance state changes each clock
    cycle to eliminate the tradeoff amongst conversion speed (clock cycles),
    number of bits (resolution) and power consumption that occurs in ADCs.

  • Simplification ? The simplification of the circuits
    considerably reduces the power consumption at the same clock frequency as
    compared to circuits using ADCs.

  • Reduced Silicon Footprint ? Invention simplifies the
    corresponding integrated circuit design and reduces the silicon area
    significantly.

  • Return Loss Calculation ? Logarithmic power detectors
    greatly reduce the requirements for the dynamic range of the following stages
    and simplify the calculation of return loss significantly.