A fully integrated ultra-low-power step-down DC-DC converter in 65nm is presented. The purpose of this converter is to convert battery voltage levels, in the range of 2.5-3V, to digital and ...mixed-signal voltage levels for low-power always-on domains. A down-conversion with a ratio of 5:1 is employed to provide a digital voltage level near the threshold voltage (Vth), which ranges from 0.55-0.6V. Higher voltage levels, such as 1.2V and 1.8V, are also made available for analog circuits. To achieve high-speed regulation at low power, an inverter-based comparator is utilized. Silicon results indicate an Efficiency-Enhancement-Factor (EEF) of 66% and a power density of 2.56 mW/mm2 at an output power of <inline-formula> <tex-math notation="LaTeX">100\mu </tex-math></inline-formula>W. These parameters represent the state-of-the-art for this level of power. The DC-DC converter exhibits a fast transient response, leading to minimal droops and overshoots, even for a 50pF output capacitor.
A generalized structure that is capable of implementing power-law filters derived from 1st and 2nd-order mother filter functions is presented in this work. This is achieved thanks to the employment ...of Operational Transconductance Amplifiers (OTAs) as active elements, because of the electronic tuning capability of their transconductance parameter. Appropriate design examples are provided and the performance of the introduced structure is evaluated through simulation results using the Cadence Integrated Circuits (IC) design suite and Metal Oxide Semiconductor (MOS) transistors models available from the Austria Mikro Systeme (AMS) 0.35 μm Complementary Metal Oxide Semiconductor (CMOS) process.
U radu je predstavljena realizacija nisko-propusnog aktivnog-RC filtra trećeg reda koji upotrebljava novu "leap-frog" (LF) topologiju. Nova struktura je pojednostavljena LF struktura s elementima ...koji se računaju direktno iz koeficijenata prijenosne funkcije. Nekoliko inačica krugova je prikazano i obavljena je usporedba. Napravljena je usporedba tako.er i s drugim uobičajenim filtarskim sekcijama trećeg reda. Novi LF filtar ima smanjeni broj komponenata, smanjenu kompleksnost i jednostavniji postupak projektiranja u usporedbi s klasičnim filtrima. Za ilustraciju učinkovitosti predstavljenog novog LF filtra, provedena je analiza osjetljivosti pomoću Schoefflerove mjere osjetljivosti i analiza termičkog šuma na izlazu na primjerima s prijenosnim funkcijama po Butterworthu i Chebyshevu s valovitošću u području propuštanja od 0.5 dB. Pomoću PSpice-a s modelom pojačala TL081, filtarska svojstva su simulirana, uspore.ena i potvr.ena mjerenjima na filtrima realiziranim pomoću diskretnih elemenata na štampanoj pločici. U radu su dane sve potrebne jednadžbe u postupku projektiranja korak po korak.
This paper presents the realization of third-order low-pass active-RC filters using a new Leap-Frog (LF) topology. New structure is a simplified LF structure with the elements calculated directly ...from the transfer function coefficients. Several versions of the circuits are presented and compared. The comparison to other common third-order filter sections is done, as well. The new LF filter has the reduced number of components, reduced complexity and straightforward design procedure compared to classical filters. As an illustration of the efficiency of the proposed new LF filter, the sensitivity analysis using Schoeffler sensitivity measure as well as output thermal noise analysis was performed on examples with Butterworth and Chebyshev 0.5dB pass-band ripple transfer functions. Using PSpice with a TL081 opamp model, the filter performance is simulated and the results compared and verified by measurements on a discrete-component breadboard filter. All equations needed for the step-by-step design are given.
In this paper we present an optimal design procedure for second-and third-order active resistance-capacitance (RC) single-amplifier building blocks that are used to build a high-order ...tolerance-insensitive allpole filter. The design procedure of low-sensitivity, low-pass second- and third-order active-RC allpole filters, with positive feedback, has already been published. The design was extended to the high-pass and band-pass filters, as well as, to the filters using negative feedback. In this paper we summarize all these previously presented designs in the form of a tabulated step-by-step design framework (cookbook). The low passive sensitivity of the resulting circuits, as well as low active sensitivity features are demonstrated on the high-order Chebyshev filter examples. The resulting low passive sensitivity is investigated using the Schoeffler sensitivity measure, whereas the low active sensitivity is investigated with Matlab using finite and frequency dependent opamp gain.
In this paper it is shown that active-RC filters can be designed to have low-sensitivity to passive components and at the same time possess low output thermal noise. The design procedure of low-noise ...and low-sensitivity, positive-feedback, second- and third-order low-pass allpole filters, using impedance tapering, has already been published. The noise analysis in this paper was extended to the high-pass and band-pass filters and those with negative-feedback. The optimum designs, regarding both noise and sensitivity of most useful filter sections were summarized in the table form (as a cookbook) and demonstrated on examples. The classical methods were used to determine output noise spectral density and total rms output noise of filters. It was found that low-sensitivity filters with minimum noise have reduced resistance levels, low Q-factors, low-noise operational amplifiers and use impedance tapering design.
This paper presents an optimum tuning procedure for high-order low-pass (LP) elliptic filters. Since elliptic filters are often used to satisfy very tight specifications, they often need to be tuned ...accurately. In this paper, we describe the tuning of one biquad, the dasiatuning biquadpsila, in a cascade of biquads. It is shown by Matlab simulations that the best choice for the tuning biquad consists of the pole pair with the highest pole Q (dasiamaximum-Q polespsila) combined with the zero pair with the lowest frequency (dasiaminimum-frequency zerospsila). We also show how standard tuning procedures, such as those for the Tow-Thomas biquad, lead to excellent results. As an example, the tuning procedure is performed on a normalized seventh-order elliptic LP filter.
In this paper we compare two realisations of fourth-order band-pass filter sections: first is realized as a coupled structure, having negative feedback around two Biquadratic sections in cascade ...(CO), second is a common design of two Biquadratic sections in cascade (CA). Dynamic range optimization by equating opamp output voltage levels using signal-flow graph is presented for a single second-order GP-Biquad and for a fourth-order coupled Biquads. The reduction of sensitivity and noise is already well-known for the case of CO BP filter, with identical Biquads, when compared to the CA design. In this paper, it is shown that equating opamp output voltage levels reduces output noise even more. In that way, dynamic range is improved substantially. Because we use a general-purpose (GP) Biquad using two integrators, we can use its simple tuning features and simple design; design equations are given. Sensitivity and output thermal noise are simulated using circuit analysis program Pspice.
In this paper output noise is investigated for several fractional-order filters. Examples are given using the low-pass Butterworth current-mode active-RC filter approximations. It is demonstrated ...experimentally that as with integer-order filters, output noise decreases with decreasing order of fractional-order filters. The considered circuits use CCIIs and have two integrators in the feedback loop. The fractional-order filter has one fractional capacitance realized by a second Foster circuit. Other components are of integer order. The noise comparison is simulated with Pspice.
Optimized coupled band-pass filters Mijat, Neven; Jurisic, Drazen
2014 37th International Convention on Information and Communication Technology, Electronics and Microelectronics (MIPRO)
Conference Proceeding
Odprti dostop
In this paper we compare two versions of fourth-order band-pass (BP) filter section realized as coupled structure, having negative feedback around two Biquadratic sections in cascade, usually ...designated as Biquartic section (i.e. it is the fourth-order band-pass section). The frequency response of a filter is subject to vary from the nominal values due to the effects of aging, changing working conditions, the fabrication tolerances of passive and active elements, etc. In order to maintain the filter's characteristics inside given specifications at the time of manufacture, and as long as possible, the main requirement is to design filters with reduced sensitivity to component tolerances. The Biquartic section has significantly reduced sensitivities to the changes of passive element values, particularly within the pass band, in comparison to common cascade design. For that purpose this structure is very suitable for use as a building block of narrow band, high order BP filters. The sensitivities are further reduced by using three-amplifier biquadratic block instead of more sensitive single-amplifier block. We investigated the sensitivities of two versions of biquartic section with two extreme combinations of second-order sections q-factor values, using Schoeffler's measure, the dynamic range, and output thermal noise using analysis in PSpice. Biquartic sections used throughout the examples are realized as reduced amplifier version retaining the low sensitivities of biquartic design. They also possess simple tuning features and simple design; design equations are given.
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