Very high-Q insensitive active RC networks
TL;DR: In this article, the frequency dependence of the operational amplifiers, which has been the principal limiting factor for high stable Q at higher frequencies for networks presented in the literature, has been taken into account.
Abstract: A new circuit realizing high stable Q 's is presented. The frequency dependence of the operational amplifiers, which has been the principal limiting factor for high Q at higher frequencies for networks presented in the literature, has been taken into account. The performance of the new network is shown to be superior to the realizations thus far presented in the literature for the following reasons. The Q realized by the new circuit is independent of the operational-amplifier bandwidth, which results in a stable response. The realization is also insensitive to manufacturing tolerances and, therefore, it can be readily tuned for the desired Q and center frequency without encountering any stability problems.
Citations
More filters
TL;DR: In this article, a first-order canonical current processing all-pass filters based on the current differencing buffered amplifier, a recently introduced active element, is proposed for wideband applications.
Abstract: A new configuration realizing first-order canonical current processing all-pass filters based on current differencing buffered amplifier, a recently introduced active element, is proposed. Using this configuration, two types of first-order current-mode all-pass filters are derived. They employ only a single active element and a bare minimum number of passive components. No component-matching constrains are required. Because of the high performance of the current differencing buffered amplifier, they are suitable for wideband applications. The derived filters are cascadable because of their high output impedances and they use fewer active and/or passive components compared to their previously reported counterparts. As an application of the proposed first-order all-pass networks, a new current-mode high-Q bandpass filter, which offers a number of advantages over its counterparts, is also given.
199 citations
TL;DR: This paper characterizes the amplifier by a one-pole rolloff model and discusses the ensuing limitations on four widely used low-pass realizations.
Abstract: There are many active RC networks that implement the low-pass filter characteristic. It has been the common practice to compare these networks with regard to passive element sensitivities while assuming the amplifier to be ideal. Such an assumption gives results that disagree with experimental observations, particularly when the pole magnitudes are large. This paper characterizes the amplifier by a one-pole rolloff model and discusses the ensuing limitations on four widely used low-pass realizations. The amplifier's open-loop gain-bandwidth product is used as a parameter to generate complex-pole loci that graphically display the effect of the nonideal amplifier. The expression of the slope of these curves at the nominal pole positions is derived and first-order estimates for the resulting changes in the \omega_{0} and Q of the poles are given. These expressions can be used to determine the upper bound on the frequency \omega_{0} that these networks can effectively realize. Experimental results agree with the predicted changes. The methods have also been applied to high-pass, bandpass, band-reject, and other realizations.
123 citations
TL;DR: In this paper, the authors described an easily trimmed universal building block for active RC filters which possesses the valuable characteristic that, with suitable design, the Q -value can be made approximately independent of the gain-bandwidth product of the operational amplifiers.
Abstract: An earlier paper by the authors describes an easily trimmed universal building block for active RC filters which possesses the valuable characteristic that, with suitable design, the Q -value can be made approximately independent of the gain-bandwidth product of the operational amplifiers This makes the filter usable for high frequencies, while at the same time the dependence of the Q -value on temperature variations in the operational amplifiers is drastically reduced Design formulas are presented, as well as comparative measurements which verify the theory The building block is shown to have excellent characteristics both as a universal second-order building block and as a standard block for active ladder synthesis of bandpass filters
104 citations
TL;DR: In this article, a high-frequency large-signal very low-distortion voltage-to-current transducer is presented, where the transconductor noise is integrated over a bandwidth of 1 MHz.
Abstract: A high-frequency large-signal very low-distortion voltage-to-current transducer is presented. The total harmonic distortion (THD), for supply voltages of only +or-2.5 V, is smaller than 0.1% for fully differential input signals up to 2.4 V peak to peak (V/sub pp/). The dynamic range is on the order of 89 dB with the transconductor noise integrated over a bandwidth of 1 MHz. Moreover, this structure presents low sensitivity to transistor mismatches. An operational transconductance amplifier (OTA), based on this transconductor, has been used in an adjustable quality factor 1.8-MHz biquadratic continuous-time filter. The quality factor Q is controlled, from 2 to 50, with a novel current-source configuration. Both the OTA and the filter have been fabricated in a CMOS 3- mu m n-well process. >
90 citations
TL;DR: In this article, a voltage-mode canonical first-order all-pass filter is presented, which contains only a single resistor, a single capacitor, and a single differential difference current conveyor (DDCC).
Abstract: In this work, a voltage-mode canonical first-order all-pass filter is presented. The filter contains only a single resistor, a single capacitor, and a single differential difference current conveyor (DDCC). No passive component-matching constraints are required. A complementary metal oxide semiconductor CMOS implementation of a DDCC is given to simulate the proposed circuit with a Spice simulation program whose results illustrate the high performance of the circuit.
89 citations
Cites methods from "Very high-Q insensitive active RC n..."
...They can be used to produce various types of filter characteristics, to realize second-order and universal filters, to synthesize multiphase oscillators, and to implement high quality factor (high-Q) frequency selective filters [5], [19], [20], [ 28 ], [30]....
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References
More filters
TL;DR: In this article, the authors describe cathode-follower circuits that have stable gain, low output impedance, and a large dynamic range, which can be used to realize sharp cut-off filters at very low frequencies.
Abstract: IN THE FREQUENCY range below about 30 cps, the dissipation factors of available inductors are generally too large to permit the practical design of inductance-capacitance (LC) or resistance-inductance-capacitance (RLC) filter networks. The circuits described in the following pages were developed and collected to provide an alternative method of realizing sharp cut-off filters at very low frequencies. In many cases the active elements can be simple cathode-follower circuits that have stable gain, low output impedance and a large dynamic range.
447 citations
TL;DR: The theory emphasizes the decomposition into second-order systems that are developed, following state-space concepts, with special reference to their sensitivity, which is shown to be very low for high operational amplifier gains.
Abstract: Using state-variable flow graphs and simple operational configurations suitable for integration, a theory for insensitive transfer function realization in terms of integrated circuits is discussed. The theory emphasizes the decomposition into second-order systems that are developed, following state-space concepts, with special reference to their sensitivity which is shown to be very low for high operational amplifier gains.
328 citations
01 Dec 1964
TL;DR: In this paper, the three general categories into which the various proposed solutions tend to fall, passive feedback, active feedback, and feed forward, are discussed, and it is argued that only the passive feedback category is likely to produce solutions which are economically feasible for high frequencies and moderately high Q's.
Abstract: No completely satisfactory means for making an integrated circuit which is sharply frequency selective has yet been fully developed. The three general categories into which the various proposed solutions tend to fall, passive feedback, active feedback, and feedforward, are discussed. It is argued that only the passive feedback category is likely to produce solutions which are economically feasible for high frequencies and moderately high Q's. Approaches coming under this category include an inductor using a thin-film ferrite, a transistorized version of the well-known reactance tube circuit, and acoustically resonant piezoelectric devices. A very promising new method of solidly mounting piezoelectric resonators and an acoustically resonant transistor are described.
35 citations
01 Sep 1966
TL;DR: In this paper, the authors present synthesis procedures for the synthesis of prototype frequency selective amplifiers suitable for semiconductor integrated circuit realization, where first-order pole-sensitivity functions are used in the synthesis.
Abstract: Synthesis procedures are presented for the synthesis of prototype frequency selective amplifiers suitable for semiconductor integrated circuit realization. Constraints and degrees of freedom imposed by semiconductor integrated passive and active components are incorporated in feedback amplifier designs. In order to achieve desensitized response, first-order pole-sensitivity functions are used in the synthesis. This leads to procedures for the simultaneous realization of prescribed response and response invariance. The procedures require feedback structures with redundant transmission-loops to provide extra degrees of freedom needed in the design. Experimental results from prototype amplifiers are presented.
25 citations
01 Jan 1968
3 citations