Patent ID: 7245164

Claim:
A radio frequency doubler, comprising: emitters of a first transistor and a second transistor and a collector of a fifth transistor being connected to each other, and emitters of a third transistor and a fourth transistor and a collector of a sixth transistor being connected to each other; an emitter of the fifth transistor and an emitter of the sixth transistor being connected to each other; bases of the first and fourth transistors and a base of the fifth transistor being connected to each other via a first capacitor, and bases of the second and third transistors and a base of the sixth transistor being connected to each other via a second capacitor; collectors of the first transistor and the third transistor being connected to each other, collectors of the second transistor and the fourth transistor being connected to each other, and a tuned circuit being connected to terminals connecting the collectors of the first and third transistors and the collectors of the second and fourth transistors, the tuned circuit resonating at a double frequency; and a base terminal of the first transistor and a base terminal of the second transistor being provided with a signal source of a radio frequency band for a differential input.