An impact of introducing multi-level signals to a bandpass cascaded delta-sigma modulator

• Published in: Proceedings - International Symposium on Multiple-Valued Logic pp. 61 - 66
• Main Authors: Waho, T., Kobayashi, S., Matsuura, K.
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Los Alamitos CA IEEE 2002
• Subjects: Analog-digital conversion; Applied sciences; Delta modulation; Diodes; Electronics; Exact sciences and technology; Frequency; Integrated circuits; Integrated circuits by function (including memories and processors); Noise shaping; Resonant tunneling devices; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Signal resolution; Stability; System performance; Wireless communication; Cascade circuit; Sigma-delta modulation; High resolution; Modulator; Virtual memory; Band pass filter; Shared memory
• ISBN: 9780769514628; 0769514626
• ISSN: 0195-623X; 2378-2226
• DOI: 10.1109/ISMVL.2002.1011071

The impact of introducing multi-level signals to a bandpass delta-sigma modulator (DSM), which is of particular interest for wireless communications applications, has been investigated. A cascaded architecture is studied, since this is favorable to obtain high resolution as well as stability. By increasing the number of the signal levels from two to 16, we have improved the DSM signal-to-noise ratio by 24 dB, or by 4 bits. This amount of improvement is almost the same as that for conventional lowpass DSMs. Our simulation also indicated that, if a mismatch in intervals between levels was introduced in the DSMs, the noise-shaping characteristics were modified considerably, and the signal-to-noise ratio (SNR) decreases. The dynamic element matching technique, in particular the mismatch-shaping scheme, was proved effective to improve the SNR, even if the mismatch exists.