Showing papers on "Switched capacitor published in 1978"
TL;DR: In this paper, the authors describe design techniques for monolithic, high-precision, MOS sampled-data active-ladder filters, which are used to simulate doubly terminated LC ladder networks.
Abstract: Design techniques for monolithic, high-precision, MOS sampled-data active-ladder filters are described. Switched capacitor integrators are used to implement the "leapfrog" configuration for simulating doubly terminated LC ladder networks. Techniques are presented for designing all-pole low-pass filters, as well as methods for including transmission zeros. An approach for implementing bandpass filters is described which is derived from the conventional low-pass-to-bandpass transformation. Monolithic realizations for two different low-pass filters are briefly described which show excellent agreement with theory.
217 citations
TL;DR: A new technique for designing precision, fully integrated, high-order filters using standard MOS technology is described, and an efficient method for implementing transmission zeros is presented.
Abstract: A new technique for designing precision, fully integrated, high-order filters using standard MOS technology is described. Switched capacitor integrators have been used to realize long time constants in small areas, and by interconnecting these integrators in a `leapfrog' configuration, monolithic high-order filters have been implemented with transfer functions that are very insensitive to component variations. Experimental results are presented for an NMOS fifth-order Chebyshev low-pass ladder filter with 0.1-dB passband ripple, a cutoff frequency of 3.4 kHz when clocked at 128 kHz, and a dynamic range of 83 dB. An efficient method for implementing transmission zeros is also presented, along with a complete design example, and additional experimental results for a third-order elliptic low-pass ladder filter which achieved 90-dB dynamic range, with a total power dissipation of 18 mW in a die area of 4400 mil/SUP 2/.
190 citations
TL;DR: A general synthesis technique is described for obtaining a switched-capacitor (SC) filter from an active RC prototype that permits the processing of signals at much higher frequencies than do previously known circuit design techniques.
Abstract: A general synthesis technique is described for obtaining a switched-capacitor (SC) filter from an active RC prototype. The response of the SC filter is related to that of its prototype by the bilinear z -transform. This allows the filtering and sensitivity properties of the prototype to be preserved for the SC circuit. It also enables the designer to realize such economical and low-sensitivity circuits as the FDNR and gyrator filters. Finally, it permits the processing of signals at much higher frequencies than do previously known circuit design techniques.
103 citations
Patent•
08 Sep 1978
TL;DR: In this article, a high-pass switched capacitor biquadratic filter based on bilinear z-transform is proposed, which comprises first and second integrating operational amplifiers connected in series and in combination with a third operational amplifier that serves as a sample and hold.
Abstract: A high-pass switched capacitor biquadratic filter based on the bilinear z-transform The filter comprises first and second integrating operational amplifiers connected in series and in combination with a third operational amplifier that serves as a sample and hold and also generates one simple pole and zero pair in the circuit transfer function thereby enabling the circuit to provide for a high degree of filter efficiency in a preselected frequency range The operational amplifiers are connected to and operate in cooperation with capacitors of a predetermined size which are switched on and off continuously by two phase clock signals supplied to the circuit The loss characteristic of the filter can be programmed by varying the clocking frequency Higher order filters can be obtained by the tandem connection of second order circuit sections followed by one or more first order pole-zero section
91 citations
01 Dec 1978
TL;DR: In this article, a monolithic sample-and-hold amplifier without field-effect transistors is described, and its performance characteristics include: 3.5/spl mu/s acquisition time to 0.1 percent with a 5000-pF hold capacitor, 50 pA of droop current from 0 to 70/spl deg/C, 10/SUP 9/ charge-to-droop current ratio, and 0.3 mV of zero-scale error.
Abstract: A monolithic sample-and-hold amplifier designed without field-effect transistors is described. Various sample-and-hold configurations are compared and their merits are discussed. Unique features of the design include a diode-bridge switch and a current booster with 50 mA of drive capability to charge the hold capacitor during large signal acquisition. The output amplifier's operating conditions are changed under logic control; it functions as a fast follower in the sample mode, and as a low input current amplifier in the hold mode. Performance characteristics include: 3.5-/spl mu/s acquisition time to 0.1 percent with a 5000-pF hold capacitor, 50 pA of droop current from 0 to 70/spl deg/C, 10/SUP 9/ charge-to-droop current ratio, and 0.3 mV of zero-scale error.
70 citations
Patent•
08 Sep 1978
TL;DR: In this article, an elliptic state variable filter uses switched capacitors controlled by an arrangement of switches that provides for a frequency response independent of stray capacitors in the circuit, with a feedback connection between the output of the second operational amplifier and the circuit input to the first operational amplifier.
Abstract: An elliptic state variable filter uses switched capacitors controlled by an arrangement of switches that provides for a frequency response independent of stray capacitors in the circuit. The filter section comprises three integrating operational amplifiers connected in series, with a feedback connection between the output of the second operational amplifier and the circuit input to the first operational amplifier. Signals via a feed forward connection from the circuit input and the outputs of the first and second operational amplifier are summed by the third operational amplifier. Transmission zeros of the filter transfer function are realized independent of poles and with a feed forward arrangement which places them inherently on the unit circle and produces infinite loss at each zero frequency despite variations in capacitor ratios in the circuit.
40 citations
TL;DR: In this paper, a general procedure for the design of an active switched-capacitor filter from an actlve-RC model is given, based on trapezoidal integration, and the resulting sampled-data circuit response is related to that of the model through bilinear z-transformation.
Abstract: A general procedure is given for the design of an active switched-capacitor filter from an actlve-RC model. The process is based on trapezoidal integration. The resulting sampled-data circuit response is related to that of the model through the bilinear z-transformation.
35 citations
TL;DR: A novel switched-capacitor integrator is described which results in the mapping of the analogue frequency axis directly on the unit circle of the z-plane.
Abstract: A novel switched-capacitor integrator is described which results in the mapping of the analogue frequency axis directly on the unit circle of the z-plane. The circuit requires one extra capacitor and additional switches. It makes the design much easier and doubles the effective sampling rate.
24 citations
Patent•
15 Sep 1978TL;DR: In this paper, a control system for a VAR generator is described in which a thyristor controlled inductive element is used to provide lagging VAR's and a bank of parallel capacitors, each of which may be switched into and out of circuit cooperation independent of the other, is employed to provide discrete levels of leading VARs.
Abstract: A control system for a VAR generator is taught in which a thyristor controlled inductive element is used to provide lagging VAR's and a bank of parallel capacitors, each of which may be switched into and out of circuit cooperation independent of the other, is used to provide discrete levels of leading VAR's. The inductive element is utilized in conjunction with the discrete levels of leading VAR's to provide a continuum of VAR generation in the region between the discrete levels by providing continuously variable compensating or cancelling current for interaction with the discrete levels to provide an overall continuous range of VAR generation in the leading VAR region.
23 citations
TL;DR: A possible method for the simulation of a grounded inductor and a grounded gyrator, by active switched-capacitor combinations, is presented.
Abstract: A possible method for the simulation of a grounded inductor and a grounded gyrator, by active switched-capacitor combinations, is presented.
21 citations
Proceedings Article•
01 Sep 1978
TL;DR: In this paper, the concept of switched capacitors, originally introduced to implement integrated active filters can be applied to the realization of pseudo-RC oscillators as well, where the power consumption has to be minimized, the active part of the oscillator must be reduced to its simplest possible form.
Abstract: The concept of switched capacitors, originally introduced to implement integrated active filters can be applied to the realization of pseudo-RC oscillators as well. If the power consumption has to be minimized, the active part of the oscillator must be reduced to its simplest possible form.
01 May 1978
TL;DR: In this paper, four new active integrator configurations are reported, all of which use single grounded capacitors, and all of them use single-ground capacitors for active integration.
Abstract: Four new active integrator configurations are reported. All the circuits use single grounded capacitors.
TL;DR: A new approach for realizing high-order analog filters which can be fully integrated using a compatible bipolar and ion-implanted JFET process is described.
Abstract: A new approach for realizing high-order analog filters which can be fully integrated using a compatible bipolar and ion-implanted JFET process is described. This approach is based on the recognition that what is really needed is a long time constant monolithic integrator which can be effectively realized in a small silicon area. These integrators have been designed, fabricated, and used in a `leapfrog' or active ladder configuration to realize a fifth-order 8 kHz Chebyshev low-pass filter with 0.1 dB passband ripple. No external trimming operations and no anti-aliasing prefilter are required.
TL;DR: A solution to the problem of realising the bilinear transformation in a switched capacitor network with experimental verification is given, presented in the context of an active integrator, but is quite general.
Abstract: Recently, a new technique for filtering in MOS LSI using switched capacitors has been demonstrated (see ibid., vol.SC-12, p.592, 1977). Basically, the technique involves the replacement of resistors, in continuous active RC filter designs, with an analogous circuit using switches and capacitors in a sampled-analog equivalent. The approach creates a problem, however, in that the switched capacitor structures do not directly simulate the equivalent resistors over the useful frequency range. This leads to the necessity for Z-transform analysis, and causes the sampled analog circuit behavior to degrade from the simplicity of the continuous active equivalent. A solution to the problem of realising the bilinear transformation in a switched capacitor network with experimental verification is given. The solution is presented in the context of an active integrator, but is quite general.
TL;DR: The magnitude of a switched-capacitor resistor (sw.c.r.) is controlled by varying the switching frequency as discussed by the authors, which enables the variation of the frequency of oscillation by changing the relatively high switching frequency.
Abstract: The magnitude of a switched-capacitor resistor (sw.c.r.) is controlled by varying the switching frequency. Their use in RC oscillators enables the variation of the frequency of oscillation by changing the relatively high switching frequency. Since the high switching frequency is easily voltage-controlled, the low-frequency oscillator effectively becomes a v.c.o. giving a low-distortion sinusoidal waveform.
01 Jul 1978
TL;DR: In this article, a grounded capacitor network was analyzed to yield either a bandpass or a low-pass function by adjustment of a single resistor, and the experimental results were quite in agreement with the analysis.
Abstract: Using the single-pole model of the operational amplifier (OA) a grounded capacitor network has been analyzed to yield either a bandpass or a low-pass function by adjustment of a single resistor. The bandpass/low-pass filters are suitable for high selectivity applications at extended frequency ranges with the advantage of independent adjustment of pole-frequency, pole-Q factor, and midband/passband transmission gain. The network has low sensitivity to all the circuit parameters. The experimental results are quite in agreement with the analysis.
TL;DR: This correspondence considers the design of high-order filters using follow-the-leader feedback configurations and active-R biquadratic blocks and experimental results of a sixth-order Butterworth bandpass filter are included.
Abstract: This correspondence considers the design of high-order filters using follow-the-leader feedback configurations and active-R biquadratic blocks. Statistical sensitivities of various second-order active-R and active-RC sections are compared, and experimental results of a sixth-order Butterworth bandpass filter are also included. The FLF configuration and versatile active-R blocks are also suitable for fully integrated filters.
TL;DR: A new concept, compatible with m.o.s. or bipolar technology, for the design of monolithic analogue active filters is proposed, which uses only ratioed capacitors as passive components and is especially suitable for the implementation of high-frequency filters.
Abstract: A new concept, compatible with m.o.s. or bipolar technology, for the design of monolithic analogue active filters is proposed. The method uses only ratioed capacitors as passive components and is especially suitable for the implementation of high-frequency filters. A high-Q, f0 = 1 MHz bandpass filter is presented as an example, using a total capacitance of only 58 pF.
Patent•
02 Nov 1978
TL;DR: In this article, a sawtooth generator is connected to a holding capacitor through two switches connected in series, which are made conducting or blocked depending on the phase difference between the reference voltage and a further voltage of the same frequency.
Abstract: The circuit generates a saw-tooth voltage with phase and period equal to those of a reference voltage. The sawtooth generator can be connected to a holding capacitor through two switches connected in series. They are made conducting or blocked depending on the phase difference between the reference voltage and a further voltage of the same frequency. The capacitor is followed by an amplifier with high input impedance, pref. a voltage follower. In order to reduce interferences from the reference voltage (S2) to the scanning holding circuit (3) output signal (Um) the two switches (K1, K2) are always switched together. A third switch (K3) is controlled, by a switching signal (S2) complementary to the switching signal (S2) so that the holding capacitor (CH) is to the highest degree screened from the a.c. voltage component passing through the blocked switch (K1). In order to shorten transient processes capacitance of the capacitor (CH) is small in comparison with that of capacitor (C1) generating the saw-tooth voltage.
Proceedings Article•
01 Sep 1978TL;DR: In this paper, the authors proposed a switch capacitor accumulator for sampled data signal processing, which can be implemented either with switched capacitors /1/ or with charge transfer devices /2/.
Abstract: Accumulators are used for sampled data signal processing. They can be implemented either with switched capacitors /1/ or with charge transfer devices /2/. Switched capacitor accumulators offer the advantage of simple MOS technology and higher operating frequencies since no shift register operations are necessary but only potential equilibration between capacitors is required to obtain the desired transfer function, furthermore transfer losses do not modify the attenuation characteristics.