Apparatus for digital-to-analogue conversion
AssigneeSony Corporation
InventorToshishiko Masuda
Life of this patent
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Abstract
An apparatus for digital-to-analogue conversion. A dither generator creates a noise signal which is added to a digital input signal to produce an added output. Noise shaping is performed on the added output at a noise shaping circuit. The noise shaping circuit includes a quantizer with certain threshold levels for quantizing the added signal. A digital-to-analogue (D/A) converter converts the output of the noise shaping circuit to an analog signal. A control circuit widens the threshold levels as a level of the digital input signal becomes zero, and attenuates an input signal to the digital-to-analogue converter by about 1/K times when the threshold levels are increased by K times.
Claims15
Apparatus for digital-to-analogue conversion comprising:
- a dither generator;
- an adder for adding dither from said dither generator to a digital input signal to produce an added output;
- a noise shaping circuit having an output, for performing noise shaping on said added output;
- said noise shaping circuit including a quantizer with certain threshold levels;
- a digital-to-analogue (D/A) converter converting said output from said noise shaping circuit to an analog signal;
- and
- control means for widening said threshold levels as a level of said digital input signal becomes zero, and for attenuating an input signal to said digital-to-analogue converter by substantially 1K times when said threshold levels are increased by K times, where K is a number.
Apparatus for digital-to-analogue conversion comprising:
- a dither generator;
- an adder for adding dither from said dither generator to a digital input signal to produce an added output;
- a noise shaping circuit having an output, for performing noise shaping on said added output;
- said noise shaping circuit including a quantizer with certain threshold levels;
- a one bit digital-to-analogue (D/A) converter converting said output from said noise shaping circuit to an analog signal;
- control means for widening said threshold levels as a level of said digital input signal becomes zero, and for attenuating an input signal to said digital-to-analogue converter by substantially 1/K times when said threshold levels are increased by K times where K=2.sup.n with n being an integer, said control means performing said attenuating and said widening by bit shifting;
- and
- wherein said control means fixes a pulse duty cycle of an output from said D/A converter to 50% at a point where an AC component of said dither becomes zero and when more than four consecutive samples of output data from said noise shaping circuit equal zero.
A method for digital-to-analogue conversion comprising the steps of:
- adding a dither signal to a digital input signal to produce an added signal;
- noise shaping said added signal to produce a shaped signal;
- quantizing said shaped signal to certain threshold levels to produce a quantized signal;
- widening said threshold levels by K times, where K is a number, as a level of said digital input signal becomes zero;
- attenuating said quantized signal by approximately 1/K times when said threshold levels are increased by K times to produce an output signal.
Dependencies are inferred from the claim text.