| 摘要 |
PROBLEM TO BE SOLVED: To eliminate a harmful effect due to feedback coupling from an antenna circuit, to reduce two types of conventionally used local oscillators to one type and also to unnecessitate a bandpass filter for eliminating an image signal in a digital signal transmitter. SOLUTION: An image elimination mixer which eliminates unwanted adjacent waves by performing multiplication, addition and subtraction between the respective signals with each other, generates an orthogonal carrier signal while the oscillation frequency of a local oscillator is made a frequency being '4/3' times as high as a carrier digital signal output frequency with signals respectively having 90 deg. phase difference of a half frequency dividing circuit and a quarter frequency dividing circuit composed of a master/slave type D flip-flop as inputs, and an orthogonal modulator modulates the orthogonal carrier signal with an input digital signal and transmits and outputs the orthogonal carrier signal. |
