Method and apparatus for radio modulator and antenna driver
Abstract:
A communication device includes a pulse width modulator that is provided with an oscillator signal at a communication carrier frequency. The pulse width modulator input is an amplified reference voltage that is regulated by a feedback loop. A modulation control provides the data signal to be transmitted. The modulation control may either be provided to the amplifier mixed with the reference voltage or may be provided to the pulse width modulator. A power transistor receives the pulse width modulator output and generates a chip output signal. An external filter is connected at the chip output to filter the signal that is provided to the communication antenna and produce a carrier sinusoid with an amplitude proportional to the pulse width modulated by voltage regulation and by the modulating data input. The power source is connected to the external filter. A differential version includes differential outputs from the pulse width modulator to two power transistors and through two external filters to a differential antenna.
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