PWM converting circuit, D/A converter and PWM converting method with improved resolution
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsHiroyuki Harada, Masako Arizumi
Life of this patent
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Abstract
A pulse width modulation (PWM) converting circuit includes a pulse generator for generating two pulse signals for each bit of a basic clock pulse train, in response to the value of digital input data, and a differential amplifier for outputting a differential amplification component between the two pulse signals as a PWM signal. The pulse generator varies pulse width of a first of the two pulse signals, on a bit-by-bit basis, of the basic clock pulse train, in response to the value of the digital input data, and holds a level of a second of the two pulse signals throughout all of the bits of the basic clock pulse train, within the period of the pulse of the PWM signal.
Claims10
A pulse width modulation (PWM) converting circuit that carries out PWM conversion of each value of digital input data for each bit of a basic clock pulse train, and outputs a result of the conversion as a PWM signal, said PWM converting circuit comprising:
- a pulse generator for generating two pulse signals asserting one of a low level and a high level, for each bit of a basic clock pulse train in response to value of digital input data;
- and
- a differential amplifier for outputting a differential amplification component between the two pulse signals as the PWM signal, wherein said pulse generator varies pulse width of a first of the two pulse signals, on a bit-by-bit basis, of the basic clock pulse train, in response to the value of the digital input data, and holds a level of a second of the two pulse signals throughout the bits of the basic clock pulse train.
A digital-to-analog (D/A) converter comprising a pulse width modulation (PWM) converting circuit and a low-pass filter for waveform shaping of a PWM signal output from said PWM converting circuit, said PWM converting circuit carrying out PWM conversion of each value of digital input data for each bit of a basic clock pulse train, and outputting a conversion result as a PWM signal, said PWM converting circuit comprising:
- a pulse generator for generating two pulse signals, asserting one of a low level and a high level, for each bit of a basic clock pulse train in response to value of digital input data;
- and
- a differential amplifier for outputting a differential amplification component between the two pulse signals as the PWM signal, wherein said pulse generator varies pulse width of a first of the two pulse signals, on a bit-by-bit basis, of the basic clock pulse train, in response to the value of the digital input data, and holds a level of a second of the two pulse signals throughout the bits of the basic clock pulse train.
A pulse width modulation (PWM) converting method PWM converting each value of digital input data for each bit of a basic clock pulse train, and outputs a conversion result as a PWM signal, said PWM converting method comprising:
- generating two pulse signals, asserting one having a low level and one having a high level for each bit of a basic clock pulse train, in response to value of digital input data;
- varying a pulse width of a first of the two pulse signals, on a bit-by-bit basis, of the basic clock pulse train, in response to the value of the digital input data;
- holding a level of a second of the two pulse signals throughout the bits of the basic clock pulse train;
- and
- outputting a differential amplification component between the two pulse signals as the PWM signal.
Dependencies are inferred from the claim text.