Patent ID: 6339702
Filing Date: 2002-01-15
Classification: G01R,H03G,H04B

Abstract:
An output power detection circuit of a transmitter, comprising:a first diode to which a first load resistor is connected in series and through which a first bias direct current flows; a second diode to which a second load resistor is connected in series and through which a second bias direct current flows; and a differential amplifier in which a first voltage generated in said first load resistor is applied to one of input terminals and a second voltage generated in said second load resistor is applied to the other input terminal, wherein the first voltage generated in the first load resistor by the first bias direct current and the second voltage generated in the second load resistor by the second bias direct current are substantially equal, a voltage dependent on a power of a transmission signal is detected from said differential amplifier when a part of the transmission signal outputted from a power amplifier is outputted to the first diode, and each of the first and second diodes includes a pair of series connected diodes, the transmission signal from the power amplifier is inputted to a connection point between the pair of series connected diodes of the first diode, and the transmission signal is rectified to a double voltage by the pair of series connected diodes of the first diode.