Patent ID: 6791405
Filing Date: 2004-09-14
Classification: H03F

Abstract:
A triangular wave generating circuit used in a Class-D amplifier, comprising:an integrating unit including an amplifier and a capacitor inserted between the input terminal and output terminal of the amplifier; a first constant-current unit which recharges the capacitor so that the output of the amplifier approaches a first predetermined voltage; a second constant-current unit which recharges the capacitor so that the output of the amplifier approaches a second predetermined voltage; a current setting unit which sets currents of the first and second constant-current units; a first switch unit which makes ON/OFF control of the current flowing in the first constant-current unit; a second switch unit which makes ON/OFF control of the current flowing in the second constant-current unit; a first comparing unit which compares the output of the amplifier with the first predetermined voltage and outputs a signal when the output of the amplifier coincides with the first predetermined voltage; a second comparing unit which compares the output of the amplifier with the second predetermined voltage and outputs a signal when the output of the amplifier coincides with the second predetermined voltage; and a flip-flop whose output signal is inverted depending on the output of the first and second comparing unit, the flip-flop making ON/OFF control of the first and second switch units.