Linear transmitter
AssigneeNippon Telegraph and Telephone Corporation
InventorsKouji Chiba, Toshio Nojima, Yasushi Yamao, Shigeru Tomisato, Tadao Takami
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Abstract
This invention relates to a linear transmitter which controls the bias voltage of either the drain electrode or collector electrode of an amplifier for radio frequency based on the envelope of the modulated signal, and is characterized in that it controls the bias voltage of the radio frequency amplifier in digital arithmetic processing by generating the envelope using in-phase envelope component and quadrature envelope component obtained from the base band signals.
Claims12
A linear transmitter including a modulation unit which modulates an input signal in amplitude, an RF power amplifier which amplifies the modulated signal outputted from said modulation unit with a solid state amplification device with a grounded source or a grounded emitter and operating using a bias voltage, and a bias means which outputs a DC voltage substantially proportional to an envelope of said modulated signal as the bias voltage of said power amplifier, which is characterized in that said modulation unit includes a complex envelope generator which generates an in-phase envelope component and a quadrature envelope component of the modulated signal out of the input signal, a quadrature modulator which generates the modulated signal with said in-phase envelope component and quadrature envelope component, and drain voltage controlling means which obtains the envelope out of said in-phase envelope component and said quadrature envelope component and supplies the same to said bias means.
Dependencies are inferred from the claim text.