A general compensation for a switched-capacitor double-integrator biquad
TL;DR: In this article, a compensation scheme was proposed to reduce transfer function errors in a switched-capacitor biquad, due to the finite gain-bandwidth product of the op amps.
Abstract: The finite frequency-dependent gain characteristics of operational amplifiers (op amps) is an important limiting factor in the performance of active s witched-capaci tor filters at high pole-frequencies and high quality-factors. A compensation scheme is given to reduce transfer-function errors in a switched-capacitor biquad, due to the finite gain-bandwidth product of the op amps. Experimental and theoretical results show that the scheme is very useful.
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IBM1
TL;DR: In this article, a digital-to-analog converter (DAC) is proposed for converting a digital signal (DS) into an analog signal (UOUT) having a maximum voltage range which corresponds to a second supply voltage (UH).
Abstract: A digital to analog converter (DAC) for converting a digital signal (DS) having a maximum voltage range which corresponds to a first supply voltage (UL) into an analog signal (UOUT) having a maximum voltage range which corresponds to a second supply voltage (UH). The first supply voltage (UL) is offered between a first supply terminal (VSS) and a second supply terminal (VDDL). The second supply voltage (UH) is offered between the first supply terminal (VSS) and a third supply terminal (VDDH). The digital to analog converter (DAC) comprises conversion resistors (RCNV0 - RCNVn) and coupling means (CPL) for coupling a number of said conversion resistors (RCNV2 - RCNVn) in between the first supply terminal (VSS) and an output terminal (OUT), and for coupling the remainder of said conversion resistors (RCNV0 - RCNV1) in between the third supply terminal (VDDH) and the output terminal (OUT). The value of said number depends on the data content of the digital signal (DS). Digital to analog converters are generally implemented in ICs. For modern ICs there is a trend toward ever decreasing supply voltages. Often circuits implemented in new IC processes have to be able to interface with ICs processed in less modern processes which are generally operated on higher supply voltages. In the modern process, therefore, circuits designed in modern ICs have to cope with voltages which are above the maximum specification for their transistors or other components. The DA-converter (DAC) mentioned above fulfils this requirement by the fact that material, such as polycrystalline silicon, is used for the conversion resistors (RCNV2 - RCNVn), which material can cope with relatively high voltages, and furthermore by the fact that only the coupling means (CPL) have to be designed to cope with relatively high voltages.
52 citations
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TL;DR: Discusses the effects of finite operational-amplifier gain and bandwidth on the response of the most widely used switched-capacitor filter section.
Abstract: Discusses the effects of finite operational-amplifier gain and bandwidth on the response of the most widely used switched-capacitor filter section. Formulas are derived for the minimum acceptable values of the DC amplifier gain and the unity-gain frequency under specified conditions.
111 citations