Multi-mode amplifier bias circuit

A current mirror amplifier (CMA) comprises:

• A. a composite master transistor, the composite master transistor comprising at least two transistor elements;
• B. a composite slave transistor, the composite slave transistor comprising at least two transistor elements;
• C. a buffering transistor having a control terminal connected to a current-sink terminal of the master transistor and providing an output connected to control terminals of the composite master transistor and the composite slave transistor and the currentsink terminal of the composite slave transistor;
• D. a first switch connected to at least one of the at least two transistor elements of the composite master transistor;
• and
• E. a second switch connected to at least one of the at least two transistor elements of the composite slave transistor.

A method of biasing an RF amplifying transistor at least two operating points via a bias circuit comprising a composite master transistor connected to the RF amplifying transistor in a current-mirror configuration and comprising at least two transistor elements, the method comprising the steps of:

• A. providing a path for a reference current through a current-sink terminal of the composite master transistor;
• and
• B. providing one of the at least two transistor elements to generate a first bias signal;
• and
• C. providing another of the at least two transistor elements to generate a second bias signal, wherein second bias signal is different from the first bias signal.

A method for manufacturing a bias circuit comprising the steps of:

• A. fabricating a composite transistor having at least two parallel-connected transistor elements;
• B. fabricating a buffering transistor, the buffering transistor being connected as emitter-follower between the current-source and control terminals of the master transistor;
• and
• C. connecting a switch to at least one of the at least two transistor elements.