Motorola Corporation

Daniel C Brayton

Robert S Kaltenecker

Bill Tabano Agar, Jr

Ngai-Ming Lau

Jeffrey K Jones

An active bias compensation circuit (110) senses a quiescent current flowing in an amplifier (130) and adjusts the quiescent current to maintain an optimal DC biasing of the amplifier (130) over a wide range of factors, e.g., temperature variation, process variation, history of the amplifier (130), etc. The compensation circuit (110) includes two transistors (101, 102) forming a difference amplifier. A sensing voltage proportional to the quiescent current and a reference voltage are applied to the base electrodes of the two transistors (101, 102), which generates a bias signal in response to a difference between the sensing voltage and the reference voltage. The bias signal adjusts the quiescent current in the amplifier (130).

Amplifier with active bias compensation and method for adjusting

A wide bandwidth linear amplifier (10) that has an operating band in excess of 1 GHz mounts the high power dissipating components (11) of the amplifier (10), and the components 917, 18) that control the high frequency gain and stability of the amplifier (10) onto a daughter board (32) that has a high thermal conductivity. The daughter board (32) and the remaining circuit components (21, 22, 23, 24, 26a, 26b) are then mounted on a mother board (31) that has a lower thermal conductivity. The assembly (30) reduces the circuit's parasitic inductance (46, 47, 48, 49) and parasitic capacitance (51, 52), and provides unconditional stability at high frequencies.

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Covina, CA, United States of America

Daniel C Brayton