This chapter described a number of data conversion circuit techniques, both for A/D and D/A, which can be employed in a wide variety of system applications which may need conversion speeds up to the order of several hundreds of kHz, or even few MHz, and conversion resolutions ranging from 8-bit to 16-bit. Firstly, we presented one of the most popular architectures for realising A/D converters with conversion resolution from 10-bits to 16-bits and conversion speeds between the audio and the video frequency bands and which is based on the well known combination of the successive approximation algorithm together with self-calibrating techniques. Then, we described a low-cost quasi-passive D/A converter yielding up to 8-bit resolution and conversion speeds up to a few MHz, and a capacitance-ratio-independent D/A converter which can achieve high conversion resolutions using operational amplifiers with relatively modest values of the DC gain. Both types of converters can be easily programmed by digital means to achieve different conversion characteristics, both for speed and resolution. Finally, we considered an algorithmic D/A converter with a built-in filtering function to shape the resulting output analogue signals, as required in a complete mixed-signal digital-to-analogue interface system. Various examples of a CMOS integrated circuit implementation were also presented to illustrate the circuit design techniques described for the self-calibrated and algorithmic converters.
Self-calibrating and algorithmic converters, Page 1 of 2
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