| 摘要 |
Circuits for modulating an RF input signal applied to an RF high power amplifier to produce a modulated RF output signal. The present invention employs a VHF power supply or converter with a modulation control circuit that enables the power supply to be pulsed at frequencies commensurate with a radar in which it is employed, for example. Modulation of the high power amplifier is accomplished by applying a pulsed voltage output signal to a DC bias input of the high power amplifier. More particularly, the modulation control circuit receives a logic control signal, generates a pulse control signal in response thereto, and modulates a DC input signal processed by the converter. The VHF converter receives and modulates the DC input signal in response to the pulse control signal to cause the pulsed voltage output signal from the converter to pulse at a rate and duty cycle determined by the logic control signal. The output signal modulates the RF input signal amplified by the RF high power amplifier. The modulation control circuit comprises a digital input buffer for receiving the logic control signal, a driver circuit for generating the pulse control signal, and a modulation switch coupled to the converter for modulating the DC input signal in response to the logic control signal. This causes the output of the converter to pulse at a rate and duty cycle determined by the logic control signal. The converter may comprise a common emitter converter or a common base converter. The VHF converter comprises input and output wave shaping networks, the common base or common emitter inverters, an impedance matching network, and a rectifier/filter. The rectifier/filter is adapted to convert a sinusoidal signal produced by the inverter into the output signal that has a desired DC voltage for application to the high power amplifier.
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