Simple and minimally invasive methods and systems for sensing and computing load impedance

#The subject matter disclosed herein relates generally to systems and methods for operating electronic devices. More particularly, the subject matter disclosed herein relates to systems and methods for sensing and computing a load impedance for a tunable matching network.

#Tunable matching networks are expected to play an important role in the realization of adaptive and reconfigurable radio front-end architectures. One particular example is the compensation of handset antenna impedance mismatch loss caused by user proximity effects using tunable antenna impedance matching networks.

#Different matching network topologies have been reported in the literature. Basic L-type networks are able to achieve conjugate matching over a limited Smith chart region. On the other hand, pi-networks provide an extra degree of freedom that enables conjugate matching over a substantially wider impedance range. In the ideal case where the component values range is unbounded [0,∞], pi-networks can provide complete Smith Chart coverage and the component values for perfect conjugation matching can be calculated by using approaches known in the art.

#The features and advantages of the present subject matter will be more readily understood from the following detailed description which should be read in conjunction with the accompanying drawings that are given merely by way of explanatory and non-limiting example, and in which:

#FIG. 1A is a chart illustrating coverage success over the Smith chart for a tuning method that minimizes the voltage standing wave ratio;

#FIG. 1B is a graph illustrating the power delivered by a network tuned based on minimization of the voltage standing wave ratio;

#The present subject matter provides systems and methods that can be used for sensing and computing a load impedance that is present at one port of a network. In the case that the two-port network is tunable (particularly in the case of a load or impedance tuner), this load information can be used together with an appropriate algorithm to control the overall circuit response. For the tuner case, this would be to set the tuner to maximize delivered power into the measured load. In one aspect, the systems and methods can be based on closed-form formulas and a direct calculation procedure. Although the term “load impedance” is used herein, those having ordinary skill in the art will recognize that the systems and methods disclosed herein can be applied to determine the load impedance, admittance, and/or the reflection coefficient.

#It is acknowledged that in the case of a matching network without loss, tuning for achieving conjugation match or minimizing the reflection coefficient means maximizing the power transfer to the load. In reality, however, the matching network has a certain amount of loss, and the minimization of the reflection coefficient does not necessarily result in maximization of power transfer. Thus, where the final matching goal is maximizing the power delivered to the load, any impedance matching approach or method based on (or partially based on) minimizing the input reflection coefficient only has good accuracy for lossless and low loss matching networks or tuners.

#The scope of application of this method is not exclusive to antenna impedance tuning control as it can, for example and without limitation, be used for tunable or non-tunable matching network design or performance analysis to replace an optimization tool.