Present and Future Trends in Integrated Analog Signal Processing Circuits


IEICE TRANSACTIONS (1976-1990)   Vol.E71   No.12   pp.1177-1188
Publication Date: 1988/12/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: REVIEW PAPER

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Analog signal processing is important for the following reasons. There exist many analog environments, and integrated analog circuits have several advantages over digital circuits. On the other hand, a digital approach can provide another features, such as accurate operation and programmability. Therefore, both circuits are effectively combined, resulting in high performance LSIs. This tutorial paper provides an overview for the recent and future trends in design and applications of integrated analog signal processing circuits. First, design techniques are reviewed for operational amplifier (Op-Amp), monolithic bipolar active RC circuits, switched-capacitor (SC) circuits, continuous-time MOS circuits, and analog-to-digital converter (ADC). High frequency filter realization, up to 100 MHz, has been tried by bipolar active RC circuits and GaAs circuits. Improved design techniques for SC circuits have been proposed. They include noise cancellation and building blocks with reduced sensitivity to nonideal Op-Amp performance. In order to overcome some SC circuit drawbacks due to a sampled data circuit, continuous-time MOS circuits have been proposed. Successful results have been obtained by using an automatic tuning method. A multi-stage noise shaping ADC is very useful to integrate an accurate ADC. A high signal-to-noise ratio (SNR), more than 91 dB, was obtained by the three-stage ADC, which can be applied to digital audio system. Automatic design and fabrication processes are also important aspects. Silicon compilers for SC circuits are overviewed. Systematic design rule, by which a globally optimum solution can be obtained, requires further investigation. A mixed analog/digital master slice LSI has been proposed to simplify an LSI customizing process. A voice-band MODEM LSI has been developed, resulting in good filter responses and SNR. Finally, promising applications of integrated analog circuits are briefly reviewed. Analog circuits are superior to a digital version in operating speed, power dissipation and integration density. In actuality, however, both approaches will be combined, resulting in mixed analog/digital LSIs where both circuits supplement each other's excellent features and negate drawbacks.