Equal-valued Capacitors Research Articles

Third-order voltage-mode active-C band pass filter

In this research article, a new third-order voltage-mode active-C asymmetrical band pass filter is proposed. It uses three numbers of current-controlled current conveyors and three numbers of equal-valued capacitors. The topology has the following important features: uses only three active elements, uses three capacitors, uses all grounded capacitors and no resistor is suitable for integrated circuit design, there is no matching constraint, high input impedance, low output impedance, central frequency can easily be electronically controlled by bias current, and frequency response is asymmetrical in nature. The application of the proposed topology in the realisation of a voltage-mode sixth-order symmetrical band pass filter has been demonstrated. The workability of the proposed topology and sixth-order filter has been confirmed by simulation results using 0.35-µm Austria Micro Systems complementary metal oxide semiconductor technology.

Noise‐shaping SAR ADC using three capacitors

A simple and highly efficient successive-approximation registers (SAR) ADC realisation is proposed. It requires an opamp, a comparator and only three equal-valued capacitors. The proposed scheme is insensitive to the capacitor parasitics, and has a small capacitance spread. With an oversampled scheme, it also allows noise-shaping the remaining quantisation error. It is well-suited for low-frequency instrumentation and measurement applications, and for use in extended-counting ADCs.

Voltage Mode Universal Biquad Using CCCII

This paper proposes a multi-input single-output (MISO) second-order active-C voltage mode (VM) universal filter using two second-generation current-controlled current conveyors (CCCIIs) and two equal-valued capacitors. The proposed circuit realizes low pass, band pass, high pass, all pass, and notch responses from the same topology. The filter uses-minimum number of passive components and no resistor which is suitable for IC Design. The filter enjoys low-sensitivity performance and exhibits electronic and orthogonal tunability of pole frequency () and quality factor () via bias current of CCCIIs. PSPICE simulation results confirm the theory.

Programmable CMOS switched-capacitor biquad using quasi-passive algorithmic DAC's

This paper describes an electrically programmable switched-capacitor (SC) biquad using quasi-passive algorithmic digital-to-analog converters (DAC's). Since only two equal-valued capacitors are needed for programming each capacitance value, the proposed technique offers compact, cost-effective programmability when compared to traditional programming techniques employing binary-weighted capacitor-arrays (C-arrays). A demonstration prototype chip realized in a 1.2 /spl mu/m CMOS double-metal double-poly technology, and which implements an 8 b programmable SC biquad giving a wide range of lowpass, bandpass and highpass filtering functions, occupies an active area of only 0.38 mm/sup 2/. >

Programmable quasi-passive algorithmic digital- analogue converter

A digital-to-analogue converter circuit is presented which employs a quasi-passive, parasitic-compensated, switched- capacitor circuit to implement a conversion algorithm consisting of a charge division between equal-valued capacitors. Both the conversion speed and resolution can be programmed by digital means to suit a wide variety of low-cost applications with conversion rates up into the megahertz range. The analogue portion of the converter has been integrated using a 2·5 μm CMOS double-poly technology and occupies a mere 0·25 mm 2. The results of the experimental evaluation of some sample prototype chips are presented and analysed.

High-speed digital-to-analogue convertor using passive switched-capacitor algorithmic conversion

A purely passive parasitic-compensated switched-capacitor circuit is shown to implement a simple signal conversion algorithm consisting of a mere charge division between equal valued capacitors. Such a circuit is the core of the new digital-to-analogue convertor described in this letter, and which is particularly suitable for high-frequency applications. Appropriate design conditions are established to render the overall circuit insensitive to the offset voltage and finite DC gain errors of the amplifier.

A new equal-valued grounded-capacitor resonator realization using current conveyor

Using a second generation current conveyor (CC II), a new resonator network containing a resistance (R)-capacitance (C)-frequency dependent negative resistance (D) series configuration is proposed. The network is canonic and both the equal-valued capacitors are grounded. ω 0 and Q of the resonator have been shown to be practically insensitive to changes in active parameters.

New equal-valued earthed-capacitor notch network using d.v.c.c.s./d.v.c.v.s.

Using the differential voltage-controlled current/differential voltage-controlled voltage source (d.v.c.c.s./d.v.c.v.s.) as the active element, a new active RC notch network is described. The network has two equal-valued earthed capacitors and the pole Q can be adjusted by single resistive control independent of the realisability condition.

Miniaturized thick-film RC-active filters for PCM application

This paper presents thick-film RC-active filters developed for use in pulse-code modulation (PCM) systems. Filters for PCM telephone transmission systems are required to be small in size and low cost in production, and they must have good performance. The filters presented have a twelve-lead single in-line package configuration. Dimensions are 5-mm thick, 10-mm high, and 30-mm wide. They meet the D3-Channel Bank requirements. The transmitting filter is a seventh-order bandpass filter (BPF). The receiving filter is a fifth-order low-pass filter (LPF) with an input RC stage which acts as a lossy sample and hold circuit. To achieve miniaturization, thick-film resistors are printed on one side of alumina substrate. On the other side, one chip of quad op-amps and monolithic ceramic-chip capacitors are assembled. Considering economical production, these filters are designed with the following features: 1) only one type of equal-valued capacitors is used; 2) to get good yields, a multiple-feedback configuration having low sensitivity to circuit elements is adopted; 3) a fast deterministic trimming method is used with computer-controlled laser-trim equipment.

Simplified design procedures for a third-order system using current conveyors

A recently proposed third-order structure using current conveyors is shown to consist of a cascade of second and first-order stages, thereby simplifying design formulae and sensitivity calculations. For realisations utilising equal-valued capacitors, the design equations form an identical set to an array previously considered for controlled-source networks. Optimum solutions based on minimum resistor sum and spread are applicable by relaxing the unity current transfer factor of one convertor.

A low-cost parallel implementation for active filters

A circuit technique is proposed, based upon a parallel-structured system, that attempts to reduce the overall component cost required for a general m-pole transfer function. The circuit uses just m nominally equal-valued capacitors, irrespective of the number of zeros. Whilst the zero sensitivity of the parallel structure is expected to be rather poorer than that for the cascade circuit, it has been found acceptable for the example described. The pole sensitivity is the same as that for the more conventional cascade structure.

Synthesis of rational transfer matrices with active RC networks using equal valued grounded capacitors

A now and practical technique for synthesizing on arbitrary rational voltage transfer function matrix T(8) with dimension q by p is presented. The realization requires a small (mostly minimum) number of grounded and equal-valued capacitors and no moro than (p + q) common ground voltage amplifiers.

Equal-valued earthed capacitor biquad configurations

Equal-valued earthed capacitor (EVEC) biquad configurations are proposed, together with a synthesis procedure. The procedure essentially consists of reducing the given second-order transfer function with a pair of complex poles to another transfer function with identical zeros, but poles shifted to the negative real axis, and then realizing this new function with two EVEC configuration proposed by Rathore and Dasgupta (1975 a).

Canonically extended EVC-ARC networks and their associated recursive formulae

Recursive formulae are derived for the determination of the voltage transfer functions of active ladder networks. The structures considered are extensions of the networks due to Huelsman, Dutta Roy and Malik for the realization of third-order equal-valued capacitor active RC filters.

Notes on the solution of EVC-ARC network equations

Criteria are presented for complete analytic solutions, in both third and fourth-order cases, of the equations describing equal-valued capacitor active RC networks.

Sensitivity Analysis of Fourth Order Filters

Expressions for the sensitivity analysis of fourth order filters are derived. Their use is illustrated by an example of an active RC circuit realisation of a fourth order lowpass Butter-worth characteristic using equal-valued resistors and capacitors.

Recursive formulae for the analysis of double-ladder single amplifier feedback systems

Recursive admittance formulae are derived for the determination of the voltage transfer function of an active ladder. The structure considered is a canonical extension of the networks due to Huelsman for the realization of equal-valued capacitor active RC filters.

Bandpass structures having equal-valued capacitors

Structures arc presented for the realization of active RC fourth-order bandpass networks having equal-valued capacitors..

Active RC realisation of a 3rd-order bandpass Butterworth characteristic using equal-valued passive elements

An active RC bandpass network that uses d.v.c.c.s./d.v.c.v.s. (a block containing a differential voltage-controlled current source and a differential voltage-controlled voltage source) with equal-valued capacitors and resistors is proposed. The sensitivities with respect to all circuit components are derived.

An active filter using equal-valued earthed capacitors†

A new active filter circuit is introduced which uses only two grounded capacitors of equal value and shown to be capable of realizing most of the second-order RC voltage transfer functions while maintaining isotropic structure. It is superior to the realization obtained by the method of Dutta Roy using one inverting amplifier.