Browse Prior Art Database

Linearity enhancement in multi-bit D/A converters

IP.com Disclosure Number: IPCOM000035665D
Original Publication Date: 2005-Feb-25
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 886K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

Multi-bit D/A converters suffer from distortions caused by the analog element mismatch. One common problem in monolithic (a single silicon chip contains the integrated circuit) D/A converters is the mismatch between its unity elements, which causes distortion products in the output spectrum. The mismatch between the elements is unavoidable, and can be reduced only by making the chip larger and consequently reducing the operation frequency. In a typical output spectrum with distortion induced by element-mismatch, there are harmonics at multiples of the frequency of the input signal, which drastically limit the SFDR (Suprious Free Dynamic Range) of the converter. Two well known techniques are commonly used to increase the SFDR: The On-Line Background Self-Calibration (OL-BSC) and the Dynamic-Element-Matching (DEM).

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Linearity enhancement in multi-bit D/A converters

Idea: Dr. Antonio Di Giandomenico, AT-Villach; Martin Clara, AT-Villach; Wolfgang Klatzer, AT-

Villach; Gori Luca, AT-Villach

Multi-bit D/A converters suffer from distortions caused by the analog element mismatch. One common problem in monolithic (a single silicon chip contains the integrated circuit) D/A converters is the mismatch between its unity elements, which causes distortion products in the output spectrum. The mismatch between the elements is unavoidable, and can be reduced only by making the chip larger and consequently reducing the operation frequency.

In a typical output spectrum with distortion induced by element-mismatch, there are harmonics at multiples of the frequency of the input signal, which drastically limit the SFDR (Suprious Free Dynamic Range) of the converter.

Two well known techniques are commonly used to increase the SFDR: The On-Line Background Self- Calibration (OL-BSC) and the Dynamic-Element-Matching (DEM).

It is proposed to use both techniques in parallel. The two techniques can be very efficiently cascaded and implemented in the decoding digital block of a given D/A converter, as shown as in Fig. 1, right after the binary-to-thermometer decoder. Since it makes the best usage of the advantages of the single two techniques, the advantage of this proposal is that it can very efficiently cancel even high amount of distortion produced by element-mismatch.

This technique is used in the...