Active impedance matching in communications systems

A system for coupling a load to a communications device comprising:

• a signal sensing module having at least a first, second, and third port;
• an impedance matching module that is automatically reconfigured to match a load whose impedance changes over time, said impedance matching module having at least a first, second, and third port;
• and
• an impedance matching control module having at least a first and second port,
• wherein said first port of said signal sensing module is for coupling to the communications device, said second port of said signal sensing module is coupled to said first port of said impedance matching module, said third port of said signal sensing module is coupled to said first port of said impedance matching control module, said second port of said impedance matching control module is coupled to said third port of said impedance matching module, and said second port of said impedance matching module is for coupling to the load,
• wherein said impedance matching module comprises a first thin film capacitor, a permittivity of said first thin film capacitor being a function of a bias voltage applied to said first thin film capacitor, and
• wherein said impedance matching module further comprises a second thin film capacitor, a permittivity of said second thin film capacitor being a function of a bias voltage applied to said second thin film capacitor.

A method for automatically matching an impedance of a load to an impedance of a communications device, comprising the steps of:

• (1) sensing a radio frequency signal;
• (2) generating a control signal, based on the radio frequency signal, that is indicative of an impedance mismatch between the load and the communications device, wherein said impedance mismatch is caused by impedance changes of the load over time;
• and
• (3) applying the control signal to a thin film capacitor to adjust an impedance of the thin film capacitor thereby reducing the impedance mismatch between the load and the communications device,
• wherein step (1) comprised the steps of obtaining a first signal that is representative of a voltage wave incident at the load, and obtaining a second signal that is representative of a voltage wave reflected at the load, and
• wherein the first and second signals are obtained using a first and second directional coupler.

A method for automatically matching an impedance of an antenna to an impedance of a communications device, comprising the steps of:

• (1) sensing a radio frequency signal;
• (2) generating a control signal, based on the radio frequency signal, that is indicative of an impedance mismatch between the antenna and the communications device, wherein said impedance mismatch is caused by impedance changes of the antenna over time;
• (3) applying the control signal to a variable impedance device thereby reducing the impedance mismatch between the antenna and the communications device,
• wherein step (1) comprises the steps of obtaining a first signal that is representative of a voltage wave incident at the antenna, and obtaining a second signal that is representative of a voltage wave reflected at the antenna, and
• wherein the first and second signals are obtained using a first and second directional coupler.

A system for coupling a load to a communications device, comprising:

• an impedance matching module that couples the communications device to the load, said impedance matching module comprising a variable impedance device having a controllable impedance, said impedance matching module having a first thin film capacitor and a second thin film capacitor;
• a signal sensing module, coupled to the communications device and the load, that develops a reference signal proportional to a signal being transferred between the communications device and the load, wherein said signal being transferred varies in response to impedance changes of the load over time;
• and
• an impedance matching control module, coupled to said impedance matching module and said signal sensing module, that automatically generates a control signal, based on said reference signal, for controlling the impedance of said variable impedance device.