Automatic RF Match Control Circuit for Broadband and Reconfigurable Wireless Devices

The bandwidth of most wireless devices is governed by the antenna's input impedance or by the impedance match between critical devices. Often, it is the antenna's reactance rather than the resistance that varies with frequency, so tuning complex impedance to purely real impedance over a broad frequency band can be quite difficult. This invention relaxes some of the design requirements of the antenna, with an intermediate matching circuit with automatic leveling and tuning. This automatic match control circuit (AMC), which employs varactor diodes for their tunability and availability, requires two parts: a tuner, and a feedback circuit that will sense the mismatch and provide the voltage correction bias to the tuner elements in order to achieve low mismatch. The AMC can dynamically reconfigure the spectral masks of the input match as a function of frequency and can correct for high VSWR effects on the outputs of power amplifiers by intelligently modifying the reactance of the circuit.

This invention increases the amount of data portable wireless devices can send per transmission and reduces the amount and severity of reflections from the load. Because it is the software, not the hardware, that is reconfigurable this invention also loosens some of the design constraints that have historically been associated with wireless devices and makes way for new and low-cost antenna packaging options. This invention could be readily used in both military and commercial applications.

Background:
Everyday the world's wireless communication systems mature and expand and the demand for improved, lower-cost portable wireless devices increases. This invention has the potential to significantly improve wireless communication capabilities by using a front-end match control circuit to automatically reconfigure the impedance and increase the bandwidth of almost all wireless devices.

Applications:

• Software design radio (SDR): robust RF filtering without changing hardware
• Low-cost antenna packaging for portable wireless devices
• Multi-function broadband radar and wireless communication systems

Advantages:

• Significantly increases bandwidth of wireless devices
• Reconfigurable: impedance matching is done with software not hardware
• Loosens design constraints associated with antennas in wireless devices
• Robust tuning: wide-range tuning possible with various loads

Status: issued U.S. Patent #8,067,997
Several tuners have been designed, fabricated and tested. Work continues on process automation. The technology is available on a non-exclusive basis.