Pulsed power amplifier for amplifying RF signals

Claim 1

A pulsed power amplifier for amplifying radio frequency signals comprising: control means for generating control signals (V control ) to control the amplifier output power so as to provide an output power pulse having rising and falling transitional phases; means for generating a subsidiary pulse signal to be applied to said control means in order to adjust a transitional phase of the output power pulse; sensing means coupled to said control means and said generating means for sensing the output power of the power amplifier, and said generating means comprises: a first comparator having a first input coupled to the sensing means for receiving a signal representing the output power of the power amplifier and a second input coupled to a first reference signal, said first comparator generating an output signal when the output power signal sensed by the sensing means is equal to the first reference signal; a first latch coupled to the output of the first comparator and to a clock and having an output, said latch being arranged to latch the value of the clock signal in response to receiving the output signal from the first comparator; a second comparator having a first input coupled to a first reference clock signal, a second input coupled to said output of the latch and an output; and variable charge pulse generating means coupled to the output of said second comparator and to said control means, said second comparator providing an output signal according to the comparison of the latched clock signal with said first reference clock signal whereby said variable charge pulse generating means generates a subsidiary pulse immediately before the start of the rising transitional phase having a magnitude responsive to the output signal from the second comparator.