| 摘要 |
PURPOSE:To independently obtain a lower side band (LSB), an upper side band (USB) and side wave band signals having phase differences in each 90 deg. by selectively obtaining a low frequency signal from four kinds of low frequency signals obtained through ah I/O means having a non-inversional I/O means and a phase inverting means. CONSTITUTION:A 90 deg. phase shifter 10 separates an input signal sin pt to be a low frequency signal into two signals sin pt, cos pt, a non-inversional amplifier 11 amplifies the input signal sin pt without chaning its phase and an inversional amplifier 12 amplifies the input signal sin pt so as to invert the phase to the reverse phase. A non-inversional amplifier 13 amplifies the input signal cos pt without changing its phase and an inversional amplifier 14 amplifies the input signal cos pt so as to invert the phase to the reverse phase. A data selector 15 switches inputs in accordance with a select signal input and selects and outputs two outputs having 90 deg. phase difference each other out of four outputs of the non-inversional amplifiers 11, 13 and the inversional amplifiers 12, 14. Consequently, eight kinds of signals consisting of LSB signals and USB signals having respectively 90 deg. phase differences can be obtained.
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