| 摘要 |
PROBLEM TO BE SOLVED: To obtain an image rejection mixer that suppresses deterioration in image rejection ratio caused by variation in manufacture and fluctuation in environmental temperature without using digital signal processing, and that has a high image rejection ratio.SOLUTION: An image rejection mixer comprises: an orthogonal signal generation circuit that generates orthogonal local oscillation signals of two systems from a local oscillation signal; a variable phase shifter that controls a phase difference between the orthogonal local oscillation signals; a feedback circuit that controls the variable phase shifter so that the phase difference between the orthogonal local oscillation signals becomes a reference phase difference; a pair of limiter amplifiers that respectively restrict amplitudes of the orthogonal local oscillation signals of the two systems; a pair of frequency converters that convert a high-frequency input signal into intermediate frequency signals of the two systems by the respective orthogonal local oscillation signals of the two systems; a 90-degree phase shifter that changes a phase difference between the intermediate frequency signals of the two systems by 90 degrees; and a synthesizer that combines the intermediate frequency signals of the two systems.SELECTED DRAWING: Figure 1 |
