Microwave amplifier linearizer

A linearizer for a microwave frequency amplifier particularly adapted to reduce harmonic distortion and intermodulation distortion from said amplifier comprising:

• a first filter having a low insertion loss for said microwave frequency including a plurality of series-connected high Q resonators;
• a second band-pass filter including a plurality of series-connected high Q resonators;
• said first and second filters being electrically connected in parallel with the common input therefor being adapted to receive the output from said amplifier;
• the center frequency of said second filter being approximately an integral multiple of said microwave frequency;
• and,
• an impedance element having a selectable impedance value connected as a load at the output of said second filter;
• the impedance of said impedance element being selected to operate in conjunction with the filter with which it is associated to tend to cause cancellation of harmonic frequency output power of said amplifier;
• whereby the presence of distortion produced harmonic frequencies and of intermodulation distortion in the output of said first filter is substantially reduced.

The method of linearizing output of an RF amplifier having a predetermined output center frequency reducing harmonics and intermodulation distortion in said output comprising the steps of:

• 1) providing said output to a plurality of filters each with at least one high Q resonator, a fundamental output port for a first one of said filters, and at least one substantially isolated harmonic frequency output port for a further one of said filters;
• 2) causing the output of said at least one substantially isolated harmonic frequency output port to be terminated in an impedance constituting a mismatch for the self-impedance of the associated filter and producing a load mismatch for said at least one harmonic frequency appearing at said at least one harmonic frequency output port;
• and
• 3) providing the output from said fundamental output port to a utilization device with a self-impedance substantially matching the self-impedance of said fundamental output port;
• whereby said impedance mismatch effectively cancels harmonic output of said RF amplifier and reduces the intermodulation distortion in the output thereof.

The method of linearizing output of an RF amplifier having a predetermined output center frequency particularly suited to a microwave application frequency thereby reducing harmonics and intermodulation distortion in said output comprising the steps of:

• 1) providing said output through a transmission line of predetermined length to a plurality of parallel-connected filters each having at least one high Q resonator, a fundamental output port for a first one of said filters, and at least one substantially isolated harmonic frequency output port for a further one of said filters;
• 2) causing the output of said at least one substantially isolated harmonic frequency output port to be terminated in an impedance constituting a mismatch for the self-impedance of the associated filter and producing a load mismatch for said at least one harmonic frequency appearing at said at least one harmonic frequency output port;
• 3) providing the fundamental output of said filter to a utilization device with a self-impedance substantially matching the self-impedance of said fundamental output port;
• whereby said load mismatch effectively cancels harmonic output of said RF amplifier and reduces the intermodulation distortion in the output thereof.