Patent ID: 8653896

Claim:
A class-AB power amplifier comprising: an amplifying element whose power supply voltage is expressed as Vdc and whose maximum current is expressed as Imax, a conduction angle θo of the amplifying element being less than 2·π(rad) and more than π(rad), and load impedance of a fundamental wave being expressed as Z 1 =R 1 +j·X 1 , load impedance of a 2nd harmonic being expressed as Z 2 =R 2 +j·X 2 , and load impedance of a 3rd harmonic being expressed as Z 3 =R 3 +j−X 3 which are observed from a dependent current source of an equivalent circuit of the amplifying element, wherein a relationship between variables X 1 and R 1 is set to −0.5·R 1 <=X 1 <=0.5·R 1 , variable R 1 is set to R 1 =Vdc/Imax·{1−cos(θo/2)}·π/{θo/2−sin(θo)/2}, variable X 2 /X 1 is set to X 2 /X 1 =−2·{θo−sin(θo)}/{sin(θo/2)−sin(1.5·θo)/3}, and variable X 3 /X 1 is set to X 3 /X 1 ={θo−sin (θo)}/{sin(θo/3−sin(2·θo)/6}, or each of the variables is set thereto so as to become equal substantially, and R 2 <⅓·R 1 is applied.