Leak power ratio detection circuit, mobile communication terminal, and control circuit for mobile communication terminal

摘要

A squaring circuit (71) squares a radio transmission signal. A band-pass filter (72) extracts a spectrum component corresponding to a desired channel, from that low-frequency component of the output of the squaring circuit (71), which occurs with a center thereof being present near a DC (Direct Current). A level measuring circuit (74) measures the level of the extracted spectrum component. On the other hand, another band-pass filter (73) extracts, from the output of the squaring circuit (71), a spectrum component corresponding to spectrum spreading due to a distortion in a transmission circuit. Another level measuring circuit (75) measures the level of this extracted spectrum component. A level radio measuring circuit (76) measures a ratio between the level measured by the level measuring circuit (74) and the level measured by the other level measuring circuit (75), and produces the measured result as a ratio of a leak power to an adjacent channel.