Design considerations and implementation of very low frequency continuous-time CMOS monolithic filters

Papananos, Y.; Georgantas, T.; Tsivdis, Y.

doi:10.1109/icecs.1996.582783

Cited by 6 publications

(4 citation statements)

References 4 publications

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“…During each cycle, the midgap interface traps distributed within an energy range are filled in the accumulation phase by capturing electrons, which are supplied by the well terminal and are emptied in the inversion phase by capturing holes, which are supplied by the source terminal. Acting as recombination centers, these traps transfer from source to well a net charge of (3) where is the electronic charge, is the gate area, and is the trap density per unit area per unit energy, which can be assumed to be energy-independent without much loss of accuracy for circuit applications. The primary model of ITCP predicts (4) where is the thermal energy, is a time constant, is the transition time of , and represents the time spent in de-pletion during each transition of .…”

Section: Primary Model Of Itcpmentioning

confidence: 99%

“…T HE low-current frontier of analog CMOS remained mostly unexplored until the beginning of 1990s. Since then, it has been challenged indirectly by a growing demand for low-power/low-voltage architectures and directly by the emergence of MOSFET log-domain processors and fully integrated low-frequency continuous-time filters [1]- [3]. Bias levels have already been reduced to the order of nanoamps in numerous applications [4]- [7] and the downward trend is likely to continue particularly in ultralow-frequency continuous-time filter applications.…”

Section: Introductionmentioning

confidence: 99%

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An evaluation of MOS interface-trap charge pump as an ultralow constant-current generator

Cilingiroglu

Becker-Gomez

Veeder

2003

IEEE J. Solid-State Circuits

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In this work, we explore the MOS interface-trap charge-pump as an ultralow constant-current generator for analog CMOS applications. Charge pumping techniques in general are more suitable than conventional continuous-time techniques for ultralow current generation because the linear controllability of current by frequency is maintained regardless of the level of current. An interface-trap pump has the same property but the minimum charge it puts out per cycle is at least two orders of magnitude smaller than that of a switched-capacitor charge pump. This helps generate the same current more accurately at a much higher frequency with a much smaller filter capacitance. The paper presents a simplified model of the terminal characteristics of the interface-trap pump and an evaluation of its performance as a stand-alone current generator. Cascoding and complementary pumping are introduced as measures of performance improvement. Temperature sensitivity, pulse feedthrough, controllability, matching, reliability, and trimming issues are addressed. Transconductor circuits built with the charge pump are presented and experimentally evaluated.

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Section: Primary Model Of Itcpmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An evaluation of MOS interface-trap charge pump as an ultralow constant-current generator

Cilingiroglu

Becker-Gomez

Veeder

2003

IEEE J. Solid-State Circuits

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“…One of the main concerns in the design of very low frequency circuits is the size of passive components [9]. Large passive components can be very expensive in terms of silicon area.…”

Section: High-valued Resistancementioning

confidence: 99%

Power and area efficient MOSFET-C filter for very low frequency applications

Tajalli

Leblebici

2011

Analog Integr Circ Sig Process

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New circuit design techniques for implementing very high-valued resistors are presented, significantly improving power and area efficiency of analog front-end signal processing in ultra-low power biomedical systems. Ranging in value from few hundreds of MX to few hundreds of GX, the proposed floating resistors occupy a very small area, and produce accurately tunable characteristics. Using this approach, a low-pass MOSFET-C filter with tunable cutoff frequency (f C = 20 Hz-184 kHz) has been implemented in a conventional 0.18 lm CMOS technology. Occupying 0.045 mm 2 /pole, the power consumption of this filter is 540 pW/Hz/pole with a measured IMFDR of 70 dB.

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“…However, the frequency of signals generated at such frontiers as biology, seismology, astrophysics, geophysics, acoustics, and vibration may be on the order of 1 Hz or less. Filtering such ultralow-frequency signals is a formidable challenge even for conventional operational transconductance amplifier-capacitor (OTA-C) circuits, which are regarded as the best in very low-frequency filter applications [1].…”

Section: Introductionmentioning

confidence: 99%

Compact sub-hertz ota-c filter design with interface-trap charge pump

Becker-Gomez

Cilingiroglu

Silva-Martínez

2003

IEEE J. Solid-State Circuits

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Single-ended and differential operational transconductance amplifier (OTA) configurations are biased with MOSFET interface-trap charge-pumping (ITCP) current generators to achieve very low transconductances for tunable sub-hertz operational transconductance amplifier-capacitor (OTA-C) filter implementation. This paper reviews the basics of ITCP current generation and presents the transconductors and the OTA-C filter configurations based on these transconductors. One of the filters is a low-pass with an experimentally determined lowest cutoff frequency of 0.18 Hz, and the other is a fully differential bandpass with individually tunable lower and upper cutoff frequencies measured down to 0.3 Hz. The former has one 15-pF filter capacitor, and measures 0.0346 mm 2 , whereas the latter contains four such capacitors and occupies 0.188 mm 2 silicon. Experimental evaluation also includes offset, harmonic distortion, and noise performance.

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Design considerations and implementation of very low frequency continuous-time CMOS monolithic filters

Cited by 6 publications

References 4 publications

An evaluation of MOS interface-trap charge pump as an ultralow constant-current generator

An evaluation of MOS interface-trap charge pump as an ultralow constant-current generator

Power and area efficient MOSFET-C filter for very low frequency applications

Compact sub-hertz ota-c filter design with interface-trap charge pump

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