Patent ID: 6624700
Filing Date: 2003-09-23
Classification: H03F

Abstract:
A radio frequency (RF) power amplifier for a mobile telephone of a spread spectrum wireless telephone system, said mobile telephone being arranged to supply said RF power amplifier with a spread spectrum signal angle modulated by in formation supplied to said mobile telephone, said spread spectrum signal having a variable amplitude dependent on the amount of power necessary to transmit said spread spectrum signal from said mobile telephone to a base station of said spread spectrum wireless system, said RF power amplifier comprising:a power transistor with a first control electrode (a) connected to be responsive to said spread spectrum signal, and (b) for controlling a variable impedance path between first and second electrodes of said power transistor; a bias circuit for supplying a bias voltage to said first control electrode, said bias circuit having a low pass filter causing said power transistor to operate in class A or AB mode as a function of said amplitude of said spread spectrum signal at said first control electrode; and a linear input stage for feeding said spread spectrum signal to said first control electrode of said amplifying transistor, said linear input stage having an inductor connected to one of first and second electrodes of an input stage transistor.