System and method for auto-bias of an amplifier

An apparatus for automatically setting a bias level for an amplifier, the apparatus comprising:

• an amplifier;
• and
• a bias control feedback circuit coupled to the amplifier that measures an operating parameter of the amplifier, adjusts a bias level of the amplifier based on the measured operating parameter when the bias control feedback circuit is closed, and maintains the bias level of the amplifier when the bias control feedback circuit is open,
• wherein the bias control feedback circuit comprises a control device that adjusts a magnitude of a signal received by the control device based on the measured operating parameter to produce a magnitude adjusted signal, thereby causing an adjustment in a bias level of the amplifier,
• wherein the control device comprises a variable voltage divider that adjusts a magnitude of a signal received by the control device based on the measured operating parameter, thereby causing an adjustment in a bias level of the amplifier,
• wherein the variable voltage divider produces a voltage signal based on the measured operating parameter, and wherein the bias control feedback circuit further comprises a sample and hold device coupled to the control device that samples the voltage signal when the amplifier is not transmitting to produce a sampled voltage and holds the sampled voltage when the amplifier is transmitting so as to sufficiently maintain the bias level as set according to the measured operating parameter,
• wherein the sample and hold device produces a sampled voltage signal based on the sampled voltage, and wherein the apparatus further comprises:
• a reference voltage source that produces a reference voltage;
• and
• an integrator coupled to the sample and hold device, to the amplifier, and to the reference voltage source, that receives the sampled voltage signal from the sample and hold device, receives the reference voltage from the reference voltage source, compares the sampled voltage signal to the reference voltage, and adjusts the bias level based on the comparison.

An apparatus for automatically setting a bias level for an amplifier, the apparatus comprising:

• an amplifier;
• a bias control feedback circuit coupled to the amplifier that measures an operating parameter of the amplifier, adjusts a bias level of the amplifier based on the measured operating parameter when the bias control feedback circuit is closed, and maintains the bias level of the amplifier when the bias control feedback circuit is open,
• wherein the bias control feedback circuit comprises a control device that adjusts a magnitude of a signal received by the control device based on the measured operating parameter to produce a magnitude adjusted signal, thereby causing an adjustment in a bias level of the amplifier,
• a reference voltage source that produces a reference voltage;
• and
• an integrator coupled to the control device and to the reference voltage source, that receives the magnitude adjusted signal from the control device, receives the reference voltage from the reference voltage source, compares the magnitude adjusted signal to the reference voltage, and adjusts the bias level based on the comparison.

A communication device comprising:

• an information source that produces a digital information input signal based on a signal modulation scheme;
• a processor coupled to the information source that produces a control signal based on the signal modulation scheme;
• a transmitter coupled to the information source and to the processor having an auto-bias feedback loop that comprises:
• an amplifier;
• and
• a bias control feedback circuit coupled to the amplifier that measures an operating parameter of the amplifier, receives the control signal from the processor, and adjusts a bias level of the amplifier based on the measured operating parameter and on the control signal,
• wherein the bias control feedback circuit includes a variable voltage divider that magnitude scales a signal received by the variable voltage divider based on a control signal received from the processor, thereby causing an adjustment of a bias level of the amplifier.

A communication device comprising:

• a transmitter having an autobias feedback loop that comprises:
• an amplifier;
• a bias control feedback circuit coupled to the amplifier that measures an operating parameter of the amplifier, adjusts a bias level of the amplifier based on the measured operating parameter when the bias control feedback circuit is in a hold mode, and maintains the bias level of the transmitter when the bias control feedback circuit is in a sampling mode;
• and
• a processor coupled to the transmitter that controls whether the auto-bias feedback loop is in the hold mode or sampling mode.

The communication device comprising:

• a transmitter having an auto-bias feedback loop that comprises:
• an amplifier;
• a bias control feedback circuit coupled to the amplifier that measures an operating parameter of the amplifier, adjusts a bias level of the amplifier based on the measured operating parameter when the bias control feedback circuit is closed, and maintains the bias level of the transmitter when the bias control feedback circuit is open;
• and
• a processor coupled to the transmitter that controls the opening and the closing of the auto-bias feedback loop,
• wherein the bias control feedback circuit comprises a control device that adjusts a magnitude of a signal received by the control device based on the measured operating parameter, thereby causing an adjustment in a bias level of the amplifier,
• wherein the control device comprises a variable voltage divider that produces a voltage signal based on the measured operating parameter, and wherein the bias control feedback circuit further comprises a sample and hold device that samples the voltage signal when transmitter is not transmitting to produce a sampled voltage and holds the sample voltage when the transmitter is transmitting so as to sufficiently maintain the bias level as set according to the measured operating parameter.

A communication device comprising:

• a transmitter having an auto-bias feedback loop that comprises:
• an amplifier;
• a bias control feedback circuit coupled to the amplifier that measures an operating parameter of the amplifier, adjusts a bias level of the amplifier based on the measured operating parameter when the bias control feedback circuit is closed, and maintains the bias level of the transmitter when the bias control feedback circuit is open;
• and
• a processor coupled to the transmitter that controls the opening and the closing of the auto-bias feedback loop,
• wherein the bias control feedback circuit comprises a control device that adjusts a magnitude of a signal received by the control device based on the measured operating parameter, thereby causing an adjustment in a bias level of the amplifier,
• wherein the control device comprises a variable voltage divider that produces a voltage signal based on the measured operating parameter, and wherein the bias control feedback circuit further comprises a sample and hold device that samples the voltage signal when the transmitter is not transmitting to produce a sampled voltage and holds the sampled voltage when the transmitter is transmitting so as to sufficiently maintain the bias level as set according to the measured operating parameter,
• wherein the sample and hold device produces a sampled voltage signal based on the sampled voltage, and wherein the communication device further comprises:
• a reference voltage source that produces a reference voltage;
• and
• an integrator coupled to the control device, to the sample and hold device, to the amplifier, and to the reference voltage source, that receives the sampled voltage signal from the sample and hold device, receives the reference voltage from the reference voltage source, compares the sampled voltage signal to the reference voltage, and adjusts the bias level based on the comparison.

A method for automatically biasing an amplifier comprising steps of:

• closing a bias control feedback circuit coupled to the amplifier;
• measuring an operating parameter of the amplifier;
• adjusting a bias level of the amplifier based on the measured operating parameter when the bias control feedback circuit is closed;
• opening the bias control feedback circuit;
• and
• holding the adjusted bias level when the bias control feedback circuit is open.

A method for automatically biasing an amplifier comprising steps of:

• closing a bias control feedback circuit coupled to the amplifier;
• measuring an operating parameter of the amplifier;
• receiving a control signal based on a signal modulation scheme;
• and
• adjusting a bias level of the amplifier based on the measured operating parameter and on the received control signal when the bias control feedback circuit is closed;
• opening the bias control feedback circuit;
• and
• holding the adjusted bias level when the bias control feedback circuit is open.