Power amplifier circuit and method of design

Abstract

Structure and design methods of electrical power amplifiers suitable for broadband application such as television frequency or white spaces. An example broadband power amplifier passes a transmit carrier with modulations from BPSK to 256 QAM, on channel bandwidths from 6 to 32 MHz, over the entire UHF television band from 470 to 800 MHz using a low voltage, low power, narrowband power amplifier transistor. Based on a push-pull technique to lower the impedance level thus improving the match and doubling the power, the wide-band power amplification is performed with a balanced polynomial filter transform structure wherein the circuit impedance increases sequentially within the filter stage. The polynomial filtering makes high selectivity of out-of-band signals thereby cleaning up harmonic signals which prevent the need for additional high selective radio frequency filters. The invented power amplifier enables efficient broadband power amplifiers having a form factor within 300 square millimeters of space.

What is claimed is: 
     
         1 . An electronic circuit comprising:
 a single-ended input port;   an input transformer;   an output transformer;   a single-ended output port; and   two single-ended amplifier legs connected from the input transformer to the output transformer, each related to a local DC power source and a local ground, both single-ended amplifier legs consisting, in order from input to output, of a first passive band-pass filter, a power amplifier, and a second passive band-pass filter, and wherein the first passive band-pass filter consists of, in order from input to output, of a series of stages where the stages are composed by a shunt capacitor to the local ground and an inductor in series, wherein each component value of each stages may be expressed as a polynomial.   
     
     
         2 . The electronic circuit of  claim 1  where the input transformer ratio and the output transformer ratio are both 1:1. 
     
     
         3 . The electronic circuit of  claim 1  where the power amplifier consists of a single transistor. 
     
     
         4 . The electronic circuit of  claim 1 , wherein the single transistor is a selected from a transistor group consisting of a Bipolar transistor, a Field Effect Transistor, a Metal Oxide Semiconductor Field Effect Transistor, and a hetero-junction transistor. 
     
     
         5 . The electronic circuit of  claim 1  where the power amplifier consists of two or more transistors with their emitters/sources connected in series. 
     
     
         6 . The electronic circuit of  claim 1  where the power amplifier consists of a transistor with its emitter/source connected to the local ground and its collector/drain connected to the emitter/source of a transistor with its base/gate connected to the local ground. 
     
     
         7 . The electronic circuit of  claim 1  where the two power amplifiers are driven by a same signal 180 degrees out of phase. 
     
     
         8 . The electronic circuit of  claim 1  where the input transformer is a transmission line transformer. 
     
     
         9 . The electronic circuit of  claim 1  where the output transformer is a Ruthroff transformer. 
     
     
         10 . The electronic circuit of  claim 1  where the input transformer has a middle access termination. 
     
     
         11 . The electronic circuit of  claim 1 , wherein each power amplifier is supplied with high impedance inductor connected to the local DC power source. 
     
     
         12 . The electronic circuit of  claim 1  where the output transformer has middle access termination. 
     
     
         13 . An electronic circuit comprising:
 a single-ended input port;   an input transformer;   an output transformer;   a single-ended output port; and   two single-ended amplifier legs connected from the input transformer to the output transformer, each related to a local DC power source and a local ground, both single-ended amplifier legs consisting, in order from input to output, of a first passive band-pass filter, a power amplifier, and a second passive band-pass filter, wherein the first passive band-pass filter consists of, in order from input to output, of a first capacitor in series, a second capacitor to the local ground, a first inductor in series, a third capacitor to the local ground, a second inductor in series, and a fourth capacitor to the local ground.   
     
     
         14 . The electronic circuit of  claim 1  where the first passive band-pass filter is adapted to perform as an impedance transform. 
     
     
         15 . The electronic circuit of  claim 1 , wherein each component value of each stage of the first passive band-pass filter may be expressed as a Chebychev polynomial. 
     
     
         16 . The electronic circuit of  claim 1  where the second passive band-pass filter is adapted to perform an impedance transform. 
     
     
         17 . The electronic circuit of  claim 1  where the second passive band-pass filter consists of, in order from input to output, of a series of stages wherein each stages comprises an inductors in series and a shunt capacitor connected to the local ground, whereby each component values of each stage may expressed as a polynomial equation such as a Chebychev polynomial. 
     
     
         18 . An electronic circuit comprising:
 a single-ended input port;   an input transformer;   an output transformer;   a single-ended output port; and   two single-ended amplifier legs connected from the input transformer to the output transformer, each related to a local DC power source and a local ground, both single-ended amplifier legs consisting, in order from input to output, of a first passive band-pass filter, a power amplifier, and a second passive band-pass filter, wherein the second passive band-pass filter consists of, in order from input to output, a third inductor to the local DC power source, a fifth capacitor to the local ground, a fourth inductor in series, a sixth capacitor to the local ground, and a seventh capacitor in series.   
     
     
         19 . The electronic circuit of claiml 8 , wherein the first passive band-pass filter consists of, in order from input to output, of a first capacitor in series, a second capacitor to the local ground, a first inductor in series, a third capacitor to the local ground, a second inductor in series, and a fourth capacitor to the local ground. 
     
     
         20 . The electronic circuit of  claim 19 , wherein the second passive band-pass filter consists of, in order from input to output, a third inductor to the local DC power source, a fifth capacitor to the local ground, a fourth inductor in series, a sixth capacitor to the local ground, and a seventh capacitor in series.