City University of Hong Kong

Kwok Wai Lau

Quan Xue

Chi Hou Chan

Wing Shing Chan

A biasing circuit is used to provide low distortion and high efficiency operation of a microwave power amplifier. The biasing circuit utilizes the nonlinear rectified current of a microwave diode or transistor for biasing the amplifying transistor self-adaptively. The biasing current not only reduces the DC bias power during low-power operation and increases self-adaptively during high-power operation, but also manipulates the intermodulation distortion minimum dynamically. Meanwhile, the biasing circuit distorts the input signals with positive gain and negative phase deviations. Therefore, the average power efficiency of the operation is enhanced, the linearity of the input-output characteristic is improved and the radiated level of adjacent channel power is suppressed.

Average power efficiency enhancement and linearity improvement of microwave power amplifiers

A power amplifier includes a bipolar transistor and a self-adaptive bias network situated between an RF input and the base of the bipolar transistor. The self-adaptive bias network suppresses the low frequency even-order intermodulation components. The self-adaptive bias network stabilizes a DC bias voltage to provide a substantially constant base-emitter voltage and provides an increased DC base current with increased input power when the power amplifier is operating within the nonlinear region.

Growing community of inventors

Hong Kong, China

Kwok Wai Lau