| 摘要 |
PROBLEM TO BE SOLVED: To provide a phase shifter improved so that a phase difference of two signals may be accurately 90 degrees over a wide frequency range (100MHz to 2GHz) as a principal purpose. SOLUTION: The phase shifter includes: an approximate 90-degree phase shifter 101 for receiving a signal with a prescribed frequency and outputting first and second signals, the amplitudes of which are equal to each other and the phase difference of which is nearly 90 degrees; an adder circuit 102 for outputting a sum of the first and the second signals; and a subtractor circuit 103 for outputting a difference between the first and the second signals. Since two output signals with the same amplitude and the same frequency as that of an oscillated signal and whose phases differ from each other by 90 degrees are obtained from the phase shifter, phase modulation conversion caused by the amplitude modulation is not generated. Since no amplitude equalization circuit is required, the phase shifter produces the two signals with a phase difference of 90 degrees within a broadband frequency range (100MHz to 2GHz) without being limited by a frequency band of phase shift operations. COPYRIGHT: (C)2007,JPO&INPIT
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