Waveform generator and waveform generating method

A waveform generator, comprising:

• a timer configured to provide a trigger signal according to a variable time period;
• and
• a digital to analog converter (DAC) configured to convert first digital data into an output voltage of an analog signal in response to the trigger signal, wherein the analog signal has a fixed waveform and a fixed frequency between a maximum voltage and a minimum voltage, and a range between the maximum voltage and the minimum voltage is divided into a plurality of voltage ranges,
• wherein the DAC comprises:
• a data hold register configured to store second digital data;
• a judgment circuit configured to provide a first control signal according to a previous output voltage of the analog signal that corresponds to the second digital data, wherein the first control signal indicates that the previous output voltage is within a first voltage range of the voltage ranges;
• and
• a calculation circuit configured to obtain the first digital data according to a second control signal, the second digital data, and a fixed voltage variation, and store the first digital data in the data hold register to update the second digital data,
• wherein the second control signal indicates whether the analog signal has a rising waveform or a falling waveform.

A waveform generating method, comprising:

• periodically providing a trigger signal according to a fixed time period;
• in response to the trigger signal, converting first digital data into an output voltage of an analog signal, wherein the analog signal has a fixed waveform and a fixed frequency between a maximum voltage and a minimum voltage, and a range between the maximum voltage and the minimum voltage is divided into a plurality of voltage ranges;
• providing a first control signal according to a previous output voltage of the analog signal that corresponds to second digital data, wherein the first control signal indicates that the previous output voltage is within a first voltage range of the voltage ranges;
• obtaining the first digital data according to a second control signal, the second digital data, and a voltage variation that corresponds to the first voltage range;
• and
• updating the second digital data according to the first digital data,
• wherein the second control signal indicates whether the analog signal has a rising waveform or a falling waveform.