Multiple operating points in a CMOS log-domain filter

Fox, R.M.; Mahalingam, Nagarajan

doi:10.1109/iscas.1999.780858

Cited by 21 publications

(15 citation statements)

References 11 publications

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“…The occurrence of unwanted limit-cycle behavior in log-domain filters is reported in [13] and investigated in [14], [15]. The appearance of multiple operating points in such filters is discussed in [16]. Reference [17] reported the appearance of multiple operating points in a square root domain filter and the way to avoid it from a circuit point of view.…”

Section: Introductionmentioning

confidence: 99%

Limit cycle behavior in a class-AB second-order square root domain filter

Blas

Feely

2011

Analog Integr Circ Sig Process

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Publication informationAnalog Integrated Circuits and Signal Processing, 68 (2) Abstract-This paper shows how an unwanted limit cycle can be exhibited by a second-order CMOS companding filter. The filter employs the quasi-quadratic law of the MOS transistor in strong inversion and saturation to achieve compression together with a Class-AB topology to extend the dynamic range. In the zero-input case, the filter operates in the manner expected of an externally-linear circuit. However, when a standard linear IC design technique is applied to it, unwanted zero-input sustained oscillations may be observed. Simulations from PSpice and measurement results from a semi-custom realization in a 0.8µm CMOS process are used to explore this behavior. This work highlights an aspect of the behavior of such filters that must be taken into account by analog designers. 2Limit Cycle Behavior in a Class-AB Second- Order Square Root Domain FilterCarlos A. De La Cruz-Blas, and Orla FeelyAbstract-This paper shows how an unwanted limit cycle can be exhibited by a second-order CMOS companding filter. The filter employs the quasi-quadratic law of the MOS transistor in strong inversion and saturation to achieve compression together with a Class-AB topology to extend the dynamic range. In the zero-input case, the filter operates in the manner expected of an externally-linear circuit. However, when a standard linear IC design technique is applied to it, unwanted zero-input sustained oscillations may be observed. Simulations from PSpice and measurement results from a semi-custom realization in a 0.8µm CMOS process are used to explore this behavior. This work highlights an aspect of the behavior of such filters that must be taken into account by analog designers.

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Section: Introductionmentioning

confidence: 99%

Limit cycle behavior in a class-AB second-order square root domain filter

Blas

Feely

2011

Analog Integr Circ Sig Process

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“…Alternate implementations of translinear circuits can be found in [4,[6][7][8]15,30,32,36] for log-domain filters, in [9,28] for RMS-to-DC converters, in [33,41,45] for oscillators, and in [40,42,45] for phase-locked loops.…”

Section: Chapter 6 Results and Conclusionmentioning

confidence: 99%

Synthesis of translinear analog signal processing systems

McDonald

Minch

The 2002 45th Midwest Symposium on Circuits and Systems, 2002. MWSCAS-2002.

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“…As described in [17], CMOS log-domain filters which contain sorne form of positive feedback loops within their topologies can suffer from this effect, which can take the form of several circuit nodes settling to unintended states. This behaviour has been observed experimentally in both the biquadratic and elliptic filters described in this work.…”

Section: Hspice Simulationsmentioning

confidence: 99%

“…A method for determining the existence of multiple operating points is described in [17], and a technique which may possibly eliminate such operating points is described in [36].…”

Section: -mentioning

confidence: 99%

“…It would be of great value to examine the effects of circuit nonidealities on performance of these CMOS log-domain filters, in a similar manner to that described in [32]. It would also be crucial to obtain a full understanding of the multiple operating points which have been observed to arise in these filters, as described in [17].…”

Section: -Directions For Future Workmentioning

confidence: 99%

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