| 摘要 |
PROBLEM TO BE SOLVED: To achieve an MSK modulation circuit 10+20 having a short startup time and not requiring PLL.SOLUTION: The MSK modulation circuit includes a rectangular wave generation circuit 11 generating two transmission signals f0, f1 by rectangular wave signals in synchronism with a data input clock CLK-DATAIN, a state determination circuit 13 determining a next transition state from current state and transmission data DATA-IN, and a waveform selection circuit 14 for selecting one of transmission signals f0, f0-, f1, f1- depending on that state and the transmission data DATA-IN, and outputting that signal. With regard to the transmission speed D and the transmission frequencies fH, fL of the transmission signals f0, f1 and a positive integer n, any one of the frequency selection conditions of a first mode, i.e., a formula (fH/D=n+0.50) and a formula (fL/D=n) are all established, or the frequency selection conditions of a second mode, i.e., a formula (fH/D=n) and a formula (fL/D=n-0.50) are all established, is satisfied. |
