US 8,018,363 B2 · Nonlinear mapping in digital-to-analog and analog-to-digital converters

Abstract

In a high-fidelity digital modulator, a mapper is provided to minimize quantization noise, jitter, and cross-talk between multiple digital-to-analog or analog-to-digital converters. The mapper receives a quantized level from a quantizer and maps the quantized level to an output sequence. The mapper includes a table defining multiple sequences corresponding to each quantized level. Each sequence includes two or more symbols, having one of multiple values. The mapper also includes a generator that selects one of the multiple sequences as the output sequence. The last symbol of a first output sequence is equal to the first symbol of the next output sequence and so on. The generator selects the output sequence by alternating between a first and a second sequence for each quantized level received. The generator selects the output sequence by alternating between sequences having a positive and a negative common mode energy for each odd valued quantized level received.

Claims22

Dependent claims

A method for generating a plurality of output sequences representing an input signal, comprising:

(a) initializing a tracking flag;
(b) receiving a quantized level value from among a plurality of quantized level values representative of the input signal;
(c) if the tracking flag is set,
(i) selecting a first output sequence that corresponds to the quantized level value from among a plurality of first output sequences, the plurality of first output sequences being characterized as having a minimum spacing of more than one clock period between transitions in adjacent output sequences, and
(ii) clearing the tracking flag;
(d) if the tracking flag is not set,
(i) selecting a second output sequence that corresponds to the quantized level value from among a plurality of second output sequences, and
(ii) setting the tracking flag;
and
(e) repeating steps (b) through (d) for each quantized level value from among the plurality of quantized level values.

7 more elements

A method for generating a plurality of output sequences representing an input signal, comprising:

(a) initializing a tracking flag;
(b) receiving a quantized level value;
(c) if the tracking flag is set,
(i) determining whether the quantized level value is an odd value,
(ii) if the quantized level value is not the odd value, generating an output sequence having a plurality of symbols, wherein the output sequence is a first sequence corresponding to the quantized level value,
(iii) if the quantized level value is the odd value, determining whether a positive common mode energy flag is set,
(iv) if the positive common mode energy flag is set, generating an output sequence having a plurality of symbols, wherein the output sequence is the first sequence corresponding to the quantized level value and clearing the positive common mode energy flag,
(v) if the positive common mode energy flag is not set, generating an output sequence having a plurality of symbols, wherein the output sequence is a second sequence corresponding to the quantized level value and setting the positive common mode energy flag, and
(vi) clearing the tracking flag;
(d) if the tracking flag is not set,
(i) determining whether the quantized level value is the odd value,
(ii) if the quantized level value is not the odd value, generating an output sequence having a plurality of symbols, wherein the output sequence is a third sequence corresponding to the quantized level value,
(iii) if the quantized level value is the odd value, determining whether the positive common mode energy flag is set,
(iv) if the positive common mode energy flag is set, generating an output sequence having a plurality of symbols, wherein the output sequence is a fourth sequence corresponding to the quantized level value and clearing the positive common mode energy flag,
(v) if the positive common mode energy flag is not set, generating an output sequence having a plurality of symbols, wherein the output sequence is the third second sequence corresponding to the quantized level value and setting the positive common mode energy flag, and
(vi) setting the tracking flag;
and
(e) repeating steps (b) through (d) for each output sequence.

15 more elements

An analog-to-digital converter, comprising:

a modulator feedback loop, wherein the modulator feedback loop includes:
a loop filter,
a quantizer configured to receive an input signal from the loop filter and to generate an output signal having a plurality of quantizer levels,
a mapper configured to map the output signal from the quantizer to an output sequence, the mapper including:
means for defining a first sequence and a second sequence for each quantizer level, and
means for selectively generating the output sequence, wherein the output sequence is one of the first sequence and the second sequence corresponding to the output quantized level;
and
a digital-to-analog converter coupled to the mapper and to the loop filter.

5 more elements

Dependencies are inferred from the claim text.

Nonlinear mapping in digital-to-analog and analog-to-digital converters

Life of this patent

Nonlinear mapping in digital-to-analog and analog-to-digital converters

Life of this patent

Abstract

Claims22