Broad-band amplifier using cascaded class C amplifiers

Claim 1

An amplifier for amplifying microwave signals above a given level over a given relatively broad band of frequencies comprising: a first avalanche diode amplifier including a first avalanche diode and a first bandpass filter with one terminal of the diode coupled to said first filter and the other terminal to a reflecting means, said first diode being reverse biased an amount requiring a signal above said given level to achieve negative conductance and amplification, said first filter adapted to apply signals only substantially at frequencies f1 through f2 above said given level to said diode and to reflect signals substantially above frequency f2 without any amplification, where frequency f1 is at one end of the broad band of frequencies and f2 is a frequency generally at the midfrequency of said broad band of frequencies; a second avalanche diode amplifier including a second avalanche diode and a second bandpass filter with one terminal of said second diode coupled to said second filter and the other terminal to a reflecting means, said second diode being reverse biased an amount requiring a signal above said given level to achieve negative conductance and amplification, said second filter adapted to apply signals only substantially at frequencies f2 through f3 above said given level to said second diode and to reflect signals substantially below frequency f2 and above frequency f3 without amplification, where f3 is at the other end of said broad band of frequencies; first means for coupling microwave signals over said relatively broad band of frequencies to said first filter, and for coupling the reflected signals at said first filter to said second filter, whereby microwave signals substantially at frequencies f1 through f2 are amplified by said first amplifier and are reflected back through said first filter and applied to said second filter and microwave signals generally above frequency f2 are reflected at said first filter and applied to said second filter without amplification; and second means for coupling the reflected signals at said second filter to an output terminal whereby microwave signals generally from frequency f2 through f3 are amplified by said second amplifier, are reflected back through said second filter and are applied to said output terminal, and microwave signals generally below frequency f2 are reflected at said second filter and are applied to said output terminal without further amplification.