Compact transmitter detection circuit with a wide dynamic range

A transmitter detection circuit comprising:

• a first rectifying circuit to rectify a transmission signal output from a power amplifier;
• a second rectifying circuit having the same structure as that of the first rectifying circuit;
• and
• a logarithmic amplifier, said logarithmic amplifier including;
• a voltage-to-current converting circuit to output an electric current that is proportional to an output voltage of said first rectifying circuit;
• and
• a two-terminal p-n junction electronic device through which the electric current flows to produce a voltage thereacross that is proportional to a logarithm of the electric current
• wherein the voltage-to-current converting circuit includes first and second transistors which perform a differential operation, a constant-current source connected to one of a collector and an emitter of the first and second transistors, and a first current-mirror circuit connected to the other of the one of the collector and the emitter of the first and second transistors,
• the output voltage of the first rectifying circuit is input to a base of one of the first transistor and the second transistor;
• an input end of the first current-mirror circuit is connected to the first transistor, and an output end of the first current-mirror circuit is connected to the second transistor, thereby causing an electric current that is equal to a difference between an electric current which flows to the second transistor and an electric current which flows to the transistor at an output end side of the current-mirror circuit to flow to the p-n junction electronic device,
• the same bias voltage is applied to rectifiers of the first and second rectifying circuits,
• the output voltage of one of the first and second rectifying circuits is input to the base of the first transistor, and
• the output voltage of the other rectifying circuit is input to the base of the second transistor.