# US 7,609,189 B1 · Interface for hybrid sigma-delta data converter

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- Number: US 7,609,189 B1
- Document ID: US7609189B1
- Status: Granted
- Kind: B1
- Application number: 12/106,902
- Filed: 2008-04-21
- Granted: 2009-10-27
- Earliest claimed: 2007-04-19
- Assignees: Marvell International Ltd.
- Inventors: Cao-Thong Tu; Heinz Maeder
- Web page: https://patentgrep.com/patent/US7609189B1

## CPC

- H03M 3/344: {by filtering other than the noise-shaping inherent to delta-sigma modulators, e.g. anti-aliasing}
- H03M 3/454: {with distributed feedback, i.e. with feedback paths from the quantiser output to more than one filter stage}
- 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)

## Abstract

A hybrid sigma-delta converter that includes a continuous-time circuit that processes an input signal and generates a first output signal, an interface circuit that receives the first output signal from the continuous-time circuit and filters the first output signal thereby generating a second output signal, and a discrete-time circuit that processes the second output signal received from the interface circuit. The interface circuit further reduces the coupling of noise generated from the operation of the discrete time circuit to the preceding continuous-time circuit.

## Claims

### Claim 1

A hybrid sigma-delta converter, comprising:
a continuous-time (CT) circuit that processes an input signal and generates a first output signal;
an interface circuit that receives the first output signal from the CT circuit and filters the first output signal thereby generating a second output signal; and
a discrete-time (DT) circuit that processes the second output signal received from the interface circuit,
wherein the interface circuit further filters noise generated from operation of the DT circuit.

### Claim 2 (depends on 1)

The converter of claim 1 wherein the noise includes high frequency perturbation.

### Claim 3 (depends on 1)

The converter of claim 1 wherein the interface circuit includes a low-pass filter.

### Claim 4 (depends on 1)

The converter of claim 1 wherein the interface circuit includes a network of passive elements.

### Claim 5 (depends on 1)

The converter of claim 1 wherein the interface circuit is configured as a T-network.

### Claim 6 (depends on 1)

The converter of claim 1 wherein the interface circuit includes a bi-directional low-pass filter.

### Claim 7

A method of operating a hybrid sigma-delta converter, comprising:
performing continuous-time processing on a sampled input signal and generating a first output signal;
filtering the first output signal to generate a second output signal;
performing discrete-time processing on the second output signal; and
filtering noise generated by the discrete-time processing of the second output signal.

### Claim 8 (depends on 7)

The method of claim 7 wherein the noise includes high frequency perturbation.

### Claim 9 (depends on 7)

The method of claim 7 further comprising performing low-pass filtering.

### Claim 10 (depends on 7)

The method of claim 7 further comprising filtering the first output signal with a network of passive elements.

### Claim 11 (depends on 10)

The method of claim 10 further comprising configuring the network of passive elements as a T-network.

### Claim 12 (depends on 7)

The method of claim 7 further comprising performing bi-directional low-pass filtering.

### Claim 13

A hybrid sigma-delta converter, comprising:
continuous-time (CT) means for processing an input signal and for generating a first output signal;
interface means for receiving the first output signal from the CT means and for filtering the first output signal thereby generating a second output signal; and
discrete-time (DT) means for processing the second output signal received from the interface means,
wherein the interface means further filters noise generated from operation of the DT means.

### Claim 14 (depends on 13)

The converter of claim 13 wherein the noise includes high frequency perturbation.

### Claim 15 (depends on 13)

The converter of claim 13 wherein the interface means includes a low-pass filter.

### Claim 16 (depends on 13)

The converter of claim 13 wherein the interface means includes a network of passive elements.

### Claim 17 (depends on 13)

The converter of claim 13 wherein the interface means is configured as a T-network.

### Claim 18 (depends on 13)

The converter of claim 13 wherein the interface means includes a bi-directional low-pass filter.