Triangular wave generating circuit with clock signal synchronization

Abstract

Disclosed is a triangular wave generating circuit with clock signal synchronization. The triangular wave generating circuit with clock signal synchronization comprises a capacitor, a first constant current source, a second constant current source, a third constant current source, a fourth constant current source, a first switching unit, a second switching unit, a high and low electrical level limiting unit, a clock signal generator and a phase detecting unit, wherein the first constant current source and the second constant current source are used for charging the capacitor; the third constant current source and the fourth constant current source are used for discharging the capacitor; the phase detecting unit is used for receiving an externally-supplied clock signal and an internal clock signal and generating a first phase signal and a second phase signal according to the phase difference of the externally-supply clock signal and the internal clock signal; the second switching unit comprises a third switch and a fourth switch, the third switch is used for responding to the first phase signal to control the coupling state of the second constant current source and the capacitor, and the fourth switch is used for responding to the second phase signal to control the coupling state of the fourth constant current source and the capacitor.

Description

technical field [0001] The invention relates to a triangular wave generating circuit, in particular to a triangular wave generating circuit synchronous with an external clock signal. Background technique [0002] The triangular wave generating circuit generates a triangular wave signal by charging and discharging a capacitor. The triangular wave generating circuit can be applied in many circuits, one of which is to convert the analog voice signal into a pulse width modulated signal in a D-type (class-D) power amplifier. [0003] figure 1 It is a known circuit 10 for generating a triangular wave signal VOUT by using a square wave signal VIN. The accuracy of the triangular wave signal will affect the performance of devices using the triangular wave signal, such as the performance of pulse width modulation (PWM) devices. In this figure, the switching frequency fsw of the triangular wave signal VOUT is equal to 1 / (TU+TD), where TU is the rising time of the triangular wave sig...

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Problems solved by technology

Similarly, question 2 reveals the triangular wave waveform when the duty cycle of the square wave is not an ideal value. The reason why question 2 often occurs is that the internal clock signal is not synchronized with the external clock signal.

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