Pulse width control circuit

Abstract

A pulse width control circuit is used to control the pulse with of a modulation signal to be written to a recording medium, such as a CD-R. The circuit controls both the leading and trailing edges of the modulation signal. The circuit includes a first delay circuit including multiple series connected first inverters for delaying the modulation signal and generating multiple first delay signals. The first delay signals are input to a first selector, which selects one of the first delay signals. A first logic circuit receives the selected first delay signal and the modulation signal and performs a first logic operation. The output of the first logic circuit is input to a second delay circuit, which includes multiple series connected second inverters for delaying the first logic circuit output signal, and generating multiple second delay signals. A second selector selects one of the plurality of delayed logic signals in accordance with the second selection signal. A second logic circuit receives the selected second delay signal and the first logic circuit output signal and performs a second logical operation, thereby generating a pulse width controlled modulation signal. The first delay circuit and first selector control the leading edge of the modulation signal, and the second delay circuit and the second selector control the trailing edge of the modulation signal.