Oversampling and noise-shaping methods for digital-to-analog (D/A) conversion have
been widely accepted as methods of choice in high performance data conversion
applications. In this thesis, the fundamentals of D/A conversion and oversampling D/A
conversion were discussed, along with the detailed analysis and comparison of the reported
state-of-the-art oversampling D/A converters.
Conventional oversampling D/A converters use 1-bit internal D/A conversion. Complex
analog filters and/or large oversampling ratios are usually needed in these 1-bit
oversampling D/A converters. Using multi-bit internal D/A conversion, the analog filter
can be much simpler and the oversampling ratio can be greatly reduced. However, the
linearity of the multi-bit D/A converter has to be at least the same as that required by the
overall system.
The dual-quantization technique developed in the course of this research provides a good
alternative for implementing multi-bit oversampling D/A converters. The system uses two
internal D/A converters; one is single-bit and the other is multi-bit. The single-bit D/A
converter is used in a path called the signal path while the multi-bit D/A converter is used
in a path called the correction path. Since the multi-bit D/A converter is not directly placed
in the signal path, its nonlinearity error can be noise shaped by an analog differentiator so
that the in-band noise contribution from the nonlinearity error is very small at the system
output, greatly reducing the linearity requirement on the multi-bit internal D/A converter.
An experimental implementation of an oversampling D/A converter using the
dual-quantization technique was carried out to verify the concept. Despite about 10 dB
higher noise than expected and the high second-order harmonic distortion due to practical
problems in the implementation, the implemented system showed that the corrected output
had more than 20 dB improvement over the uncorrected output in both signal-to-noise ratio
and dynamic range, demonstrating the validity of the concept. / Graduation date: 1996
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/34610 |
| Date | 07 June 1995 |
| Creators | Shu, Shaofeng |
| Contributors | Temes, Gabor C. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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