US 6,204,788 B1 · Digital/analog conversion apparatus

Abstract

A digital/analog conversion apparatus not causing harmonic distortion at the outputs of a row of 1-bit digital/analog converters and capable of effectively suppressing occurrence of harmonic distortion because of variations among the outputs of the 1-bit digital/analog converters, being configured as described below. More specifically, first, a digital input is converted into a digital signal having p values at a sampling frequency raised by a digital filter and a noise shaper. A decoder assigns the output of the noise shaper to a row of (p−1) 1-bit signals so that the position of value “1” is circulated, and designates the position of an inhibit bit in the row of 1-bit signals. When the assignment of value “1” is circulated to the inhibit bit position, the assignment advances to avoid the inhibit bit, and the position of the inhibit bit is moved so as to be circulated to the next bit. The row of 1-bit signals is then converted into analog signals by a row of (p−1) uniform 1-bit digital/analog converters, and the analog signals are integrated by an analog adder.

Claims17

Dependent claims

A digital/analog conversion apparatus comprising:

a digital filter for increasing the sampling frequency of an input digital signal by k (k:
an integer) times,
a noise shaper for carrying out word length limitation by using the output of said digital filter as an input and for changing the frequency characteristic of noise to a predetermined characteristic,
a decoder for using the output of said noise shaper as a decoder input and for generating and outputting a row of 1-bit signals wherein “1” is assigned to 1-bit signals, the number of which corresponds to the value of said decoder input,
a row of 1-bit digital/analog converters for converting the outputs of said decoder into analog signals, and
an analog adder for integrating the outputs of said row of 1-bit digital/analog converters, wherein
in said row of 1-bit signals, the 1-bit signal position to which value “1” is assigned is circulated, and a 1-bit signal at a predetermined position in said row of 1-bit signals is designated as an inhibit bit wherein the assignment of value “1” is inhibited so that harmonic distortion included in the outputs of said row of 1-bit digital/analog converters can be reduced.

4 more elements

A digital/analog conversion apparatus comprising:

a digital filter for increasing the sampling frequency of an input digital signal by k (k:
an integer) times,
a noise shaper for carrying out word length limitation by using the output of said digital filter as an input and for changing the frequency characteristic of noise to a predetermined characteristic,
a decoder for using the output of said noise shaper as a decoder input and for generating and outputting a row of 1-bit signals wherein “1” is assigned to 1-bit signals, the number of which corresponds to the value of said decoder input,
a row of 1-bit digital/analog converters for converting the outputs of said decoder into analog signals, and
an analog adder for integrating the outputs of said row of 1-bit digital/analog converters, wherein
in said row of 1-bit signals, the 1-bit signal position to which value “1” is assigned is circulated, a 1-bit signal at a predetermined position in said row of 1-bit signals is designated as an inhibit bit wherein the assignment of value “1” is inhibited, and said 1-bit signal position corresponding to said inhibit bit is circulated.

4 more elements

A digital/analog conversion apparatus comprising:

a digital filter for increasing the sampling frequency of an input digital signal by k (k:
an integer) times,
a noise shaper for carrying out word length limitation by using the output of said digital filter as an input and for changing the frequency characteristic of noise to a predetermined characteristic,
a decoder for using the output of said noise shaper as a decoder input and for generating and outputting a row of 1-bit signals wherein “1” is assigned to 1-bit signals, the number of which corresponds to the value of said decoder input,
a row of 1-bit digital/analog converters for converting the outputs of said decoder into analog signals, and
an analog adder for integrating the outputs of said row of 1-bit digital/analog converters, wherein
in said row of 1-bit signals, the 1-bit signal position to which value “1” is assigned is circulated, a 1-bit signal at a predetermined position in said row of 1-bit signals is designated as an inhibit bit wherein the assignment of value “1” is inhibited, and said 1-bit signal position corresponding to said inhibit bit is circulated so that harmonic distortion included in the outputs of said row of 1-bit digital/analog converters can be reduced.

4 more elements

Dependencies are inferred from the claim text.

Digital/analog conversion apparatus

Life of this patent

Digital/analog conversion apparatus

Life of this patent

Abstract

Claims17