# US 7,746,256 B2 · Analog to digital conversion using irregular sampling

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- Number: US 7,746,256 B2
- Document ID: US7746256B2
- Status: Granted
- Kind: B2
- Application number: 12/245,342
- Filed: 2008-10-03
- Published: 2009-04-09
- Granted: 2010-06-29
- Earliest claimed: 2007-10-05
- Assignees: Infineon Technologies AG
- Inventors: Andreas Wiesbauer; Lajos Gazsi
- Web page: https://patentgrep.com/patent/US7746256B2

## CPC

- H03M 1/1265: {Non-uniform sampling}
- G04F 10/005: {Time-to-digital converters [TDC] (analog-to-digital converters with intermediate conversion to time or phase H03M1/50, H03M1/60)}
- H03M 3/43: {the quantiser being a single bit one}
- H03M 3/456: {the modulator having a first order loop filter in the feedforward path}
- H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C)
- G04F: TIME-INTERVAL MEASURING (measuring pulse characteristics G01R, e.g. G01R29/02; in radar or like systems G01S)

## Abstract

This disclosure relates to analog to digital conversion using irregular sampling.

## Claims

### Claim 1

An Analog to Digital Converter (ADC) comprising:
a Asynchronous Delta-Sigma Modulator (ADSM) that modulates an analog signal into a modulated signal; and
a Time to Digital Converter (TDC) and Irregular Sampler that samples the modulated signal at non-equidistant sample values, and outputs a time-discrete non-equidistant signal, wherein the time-discrete non-equidistant signal is not dependent on a clock input.

### Claim 2 (depends on 1)

The ADC of claim 1, wherein the ADC provides noise shaping to the analog signal.

### Claim 3 (depends on 1)

The ADC of claim 1, wherein the ADC converts amplitude information of the analog signal into time information in time domain.

### Claim 4 (depends on 1)

The ADC of claim 1, wherein ADC generates an instantaneous frequency that is non-linearly dependent on the analog signal.

### Claim 5 (depends on 1)

The ADC of claim 1, wherein the TDC and Irregular Sampler quantizes the modulated signal into a signal having discrete values.

### Claim 6 (depends on 1)

The ADC of claim 1, wherein the TDC and Irregular Sampler receive a clock input and output an equidistant sample signal.

### Claim 7 (depends on 6)

The ADC of claim 6, wherein the TDC and Irregular Sampler are comprised of a first TDC and Irregular Sampler that outputs the time-discrete non-equidistant signal and a second TDC and Irregular Sampler that outputs the equidistant signal.

### Claim 8 (depends on 6)

The ADC of claim 6 further comprising a Digital Signal Processor (DSP) that generates a digital representation of the analog signal.

### Claim 9

An apparatus comprising:
an Analog to Digital Converter (ADC) that converts an analog signal into a digital signal, by modulating the analog signal into a modulate signal, by converting amplitude information of the analog signal into continuous time information, sampling at irregular asynchronous intervals the modulated signal, and reconstructing the analog signal into a digital signal based on the modulated analog signal; and
a digital modulator that modulates the digital signal.

### Claim 10 (depends on 9)

The apparatus of claim 9, wherein the ADC includes an Asynchronous Delta-Sigma Modulator and an Irregular Sampler that perform the modulating, converting and sampling.

### Claim 11 (depends on 9)

The apparatus of claim 9, wherein the ADC reconstructs the analog signal into the digital signal by quantizing and demodulating samples taken at irregular time intervals.

### Claim 12 (depends on 9)

The apparatus of claim 9, wherein the ADC provides noise shaping to reduce quantization noise.

### Claim 13 (depends on 9)

The apparatus of claim 9, wherein the digital modulator up samples the frequency of the digital signal.

### Claim 14 (depends on 9)

The apparatus of claim 9, wherein the digital modulator includes one or more of the following signal processing components: a digital filter, an up sampler, and a noise shaper.

### Claim 15 (depends on 9)

The apparatus of claim 9 further comprising a power amplifier that amplifies and increases power efficiency of the digital signal that is modulated signal by the digital modulator.

### Claim 16

A method for signal conversion, comprising:
receiving a band limited analog signal;
converting amplitude of the band limited analog signal to time, wherein a time based signal is generated;
generating irregular samples taken at non-equidistant time intervals of the time based signal; and
reconstructing a digital signal representation of the band limited analog signal based on the generated irregular samples.

### Claim 17 (depends on 16)

The method of claim 16, wherein the receiving includes applying pre-filtering to a received analog signal, if the analog signal is not band limited.

### Claim 18 (depends on 16)

The method of claim 16, wherein the converting includes converting variations in amplitude of the band limited signal to variations in pulse width and pulse period.

### Claim 19 (depends on 16)

The method of claim 16, wherein the converting includes generating the time based signal in the form of an asynchronous time continuous square wave.

### Claim 20 (depends on 16)

The method of claim 16, wherein the generating includes quantization of the irregular samples.

### Claim 21 (depends on 16)

The method of claim 16, wherein the reconstructing includes demodulating based on duty-cycle modulation to reconstruct the band limited analog signal.