| 摘要 |
<P>PROBLEM TO BE SOLVED: To display whether a triangular wave or trapezoidal wave, and a reference clock signal are synchronized in phase. <P>SOLUTION: A triangular wave-trapezoid wave generating circuit includes a waveform control circuit which switches between charging and discharging of a load capacitor by inputting a charging/discharging switching signal to a charging and discharging circuit to generate a triangular wave/trapezoid wave having a gradient between two different potentials, detects a phase difference as a difference in cycle between the triangular wave/trapezoid wave and reference clock signal, and performs control to synchronize cycles of the triangular/trapezoid wave with a cycle of the reference clock signal. The triangular wave-trapezoid wave generating circuit further includes a test circuit which receives a phase difference pulse signal corresponding to the phase difference between the triangular wave/trapezoidal signal and reference clock signal from the waveform control circuit, latches a phase difference pulse signal having a pulse width larger than a predetermined pulse width at cycles of a charging/discharging switching signal for generating the triangular wave/trapezoidal wave, and outputs it as a status signal showing whether the triangular wave or trapezoidal wave and the reference clock signal are synchronized in phase within a predetermined phase difference. <P>COPYRIGHT: (C)2010,JPO&INPIT |
