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Showing papers on "Electronic filter published in 1999"


Journal ArticleDOI
TL;DR: In this paper, three ratioed folded-beam micromechanical resonators coupled by flexural mode springs are used to suppress passband distortion due to finite-mass and process mismatch nonidealities, which become increasingly important on this microscale.
Abstract: Third order, high-Q, micromechanical bandpass filters comprised of three ratioed folded-beam resonators coupled by flexural mode springs are demonstrated using an integrated circuit compatible, doped polycrystalline silicon surface-micromachining technology. A complete design procedure for multiresonator micromechanical filters is presented and solidified via an example design. The use of quarter-wavelength coupling beams attached to resonators at velocity-controllable locations is shown to suppress passband distortion due to finite-mass and process mismatch nonidealities, which become increasingly important on this microscale. In addition, low-velocity coupling methods are shown to greatly alleviate the lithographic resolution required to achieve a given percent bandwidth. Ratioed folded-beam micromechanical resonators are introduced as the key impedance transforming components that enable the needed low-velocity coupling. Using these design techniques, balanced three-resonator microscale mechanical filters with passband frequencies centered around 340 kHz are demonstrated with percent bandwidths of 0.1%, associated insertion losses as small as 0.1 dB, 20-dB shape factors as low as 1.5, and stopband rejections greater than 64 dB. Measurement and theory are rigorously compared and important limitations, such as thermal susceptibility, the need for passband tuning, and inadequate electromechanical coupling, are addressed.

226 citations


Proceedings ArticleDOI
14 Mar 1999
TL;DR: In this paper, a general procedure for optimizing the damping of an input filter using a single resistor is presented, which is employed to derive the equations governing optimal damping for several basic filter circuits.
Abstract: A general procedure is outlined for optimizing the damping of an input filter using a single resistor. This procedure is employed to derive the equations governing optimal damping of several basic filter circuits. Design tradeoffs are discussed. Additional criteria are derived that allow employment of these results in design of multiple-section cascaded filters with damping.

200 citations


Patent
21 Sep 1999
TL;DR: In this paper, the authors present a system with controlled quality factors including a resonator having a plurality of ports and a first quality factor greater than the system quality factor, and an amplifier providing negative feedback among the ports to render the system's quality factor independent of the resonator quality factor.
Abstract: Resonator systems with controlled quality factors including a resonator having a plurality of ports and a first quality factor greater than the system quality factor, and an amplifier providing negative feedback among the ports to render the system quality factor independent of the resonator quality factor.

186 citations


Proceedings ArticleDOI
29 Nov 1999
TL;DR: In this paper, a new approach for single-phase harmonic current detection is presented, which is obtained through extending ideas of three-phase instantaneous reactive power theory and constructing a two-phase system from the existing single phase circuit.
Abstract: In this paper, a new approach for single-phase harmonic current detection is presented. The approach was obtained through extending ideas of three-phase instantaneous reactive power theory and constructing a two-phase system from the existing single-phase circuit. By theoretical and simulation analysis, it is shown to be a precise approach, which can be easily realized and has the merits of better steady state and dynamic performance than conventional approaches that could be used in single-phase circuits. The approach was applied into a hybrid active power filter, which combines a series active filter and a shunt passive filter together and aims at solving the harmonics problem originated by high-power single-phase nonlinear load. Following the system configuration and basic principles of the hybrid active power filter, the overall detection and control algorithm, the PWM generating technique and the DC voltage stabilizing method are introduced in detail. The detection and control algorithm were then realized by a digital control circuit with DSP processor, and successfully employed in a prototype hybrid active power filter. Experimental results on the prototype verified the effectiveness of the new detecting approach, the performance of the control circuit and the filtering characteristics of the hybrid active power filter.

105 citations


Journal ArticleDOI
TL;DR: A voltage-mode low-pass, band- pass, and high-pass filter with single Input and three outputs, employing only two compound current conveyors, two grounded capacitors, and three resistors, is proposed.
Abstract: A voltage-mode low-pass, band-pass, and high-pass filter with single Input and three outputs, employing only two compound current conveyors, two grounded capacitors, and three resistors, is proposed. The proposed circuit offers the following advantageous features: realization of voltage-mode low-pass, band-pass, and high-pass filter responses from the same configuration; no requirement of critical component matching conditions; employment of grounded capacitors ideal for integration; low sensitivity characteristics; and simpler configuration due to the use of only two compound current conveyors.

71 citations


Patent
Marcos Pereira1, Kadry Sadek1
16 Jun 1999
TL;DR: In this article, a hybrid filter for an alternating current network (6) is proposed, where a passive filter and an active filter are electrically connected in series, whereby the active filter has a voltage source.
Abstract: The invention relates to a hybrid filter for an alternating current network (6). The hybrid filter has a passive filter and an active filter (2,4) that are electrically connected in series, whereby the active filter (4) has a voltage source (8). According to the invention, a filter (14) adjusted to the nominal frequency of the alternating current network (6) is mounted electrically parallel to the active filter (4). This results in a hybrid filter for an alternating current network (6), whereby the active filter (4) is not subjected to fundamental frequency current component strain.

56 citations


Patent
02 Apr 1999
TL;DR: In this paper, a method and apparatus to control non-adjacent cross-coupling in a microstrip filter is presented, where the closed loop increases the transmission zero levels.
Abstract: The present invention provides for a method and apparatus to control non-adjacent cross-coupling in a micro-strip filter. In instances of weak cross-coupling, such as a filter circuit on a high dielectric constant substrate material (e.g., LaAIO3 with dielectric constant of 24), a closed loop is used to inductively enhance the cross-coupling. The closed loop increases the transmission zero levels. For strong cross-coupling cases, such as a filter circuit on a lower dielectric constant substrate material (e.g., MgO with dielectric constant of 9.6), a capacitive cross-coupling cancellation mechanism is introduced to reduce the cross-coupling. In the latter instance, the transmission zero levels are moved down.

49 citations


Proceedings Article
01 Jan 1999
TL;DR: In this article, integrated spiral microinductors suspended (approximately 60 μm) above the substrate using surface micromachining techniques to reduce the undesirable effect of substrate proximity on the inductor performance are investigated.
Abstract: To meet requirements in mobile communication and microwave integrated circuits, miniaturization of the inductive components that many of these systems require is of key importance. At present, active circuitry is used which simulates inductor performance and which has high Q-factor and inductance; however, such circuitry has higher power consumption and higher potential for noise injection than passive inductive components. An alternate approach is to fabricate integrated inductors, in which lithographic techniques are used to pattern an inductor directly on a substrate or a chip. However, integrated inductors can suffer from low Q-factor and high parasitic effects due to substrate proximity. To expand the range of applicability of integrated microinductors at high frequency, their electrical characteristics, especially quality factor, should be improved. In this work, integrated spiral microinductors suspended (approximately 60 μm) above the substrate using surface micromachining techniques to reduce the undesirable effect of substrate proximity on the inductor performance are investigated. The fabricated inductors have inductances ranging from 15-40 nH and Q-factors ranging from 40-50 at frequencies of 0.9-2.5 GHz. Microfilters based on these inductors are also investigated by combining these inductors with integrated polymer filled composite capacitors.

47 citations


Journal ArticleDOI
TL;DR: In this article, integrated spiral microinductors suspended (approximately 60 /spl mu/m) above the substrate using surface micromachining techniques to reduce the undesirable effect of substrate proximity on the inductor performance are investigated.
Abstract: To meet requirements in mobile communication and microwave integrated circuits, miniaturization of the inductive components that many of these systems require is of key importance. At present, active circuitry is used which simulates inductor performance and which has high Q-factor and inductance; however, such circuitry has higher power consumption and higher potential for noise injection than passive inductive components. An alternate approach is to fabricate integrated inductors, in which lithographic techniques are used to pattern an inductor directly on a substrate or a chip. However, integrated inductors can suffer from low Q-factor and high parasitic effects due to substrate proximity. To expand the range of applicability of integrated microinductors at high frequency, their electrical characteristics, especially quality factor, should be improved. In this work, integrated spiral microinductors suspended (approximately 60 /spl mu/m) above the substrate using surface micromachining techniques to reduce the undesirable effect of substrate proximity on the inductor performance are investigated. The fabricated inductors have inductances ranging from 15-40 nH and Q-factors ranging from 40-50 at frequencies of 0.9-2.5 GHz. Microfilters based on these inductors are also investigated by combining these inductors with integrated polymer filled composite capacitors.

46 citations


Patent
24 Feb 1999
TL;DR: In this article, a power drive apparatus consisting of a main circuit board including an input terminal block for connection to power-source wires mounted on a major surface of the main circuit, a power module including a converter unit having diodes and an inverter unit having switching devices and Diodes, the power module, mounted on the other major surface, being for converting and outputting electric power supplied through the input terminal blocks, and a heat-dissipating plate, connected with the power modules in contact with a surface opposite to the main-circuit board,
Abstract: The power drive apparatus comprises a main circuit board including an input terminal block for connection to power-source wires mounted on a major surface of the main circuit board; a power module including a converter unit having diodes and an inverter unit having switching devices and diodes, the power module, mounted on the other major surface of the main circuit board, being for converting and outputting electric power supplied through the input terminal block; a heat-dissipating plate, connected with the power module in contact with a surface of the power module opposite to the main circuit board, for dissipating heat generated by the power module; and a filter module including a filter substrate, provided with a filter circuit and being disposed in the middle of an interconnecting path between the input terminal block and an input section of the converter unit, for suppressing the transmission of noise generated by the switching devices to a power source side, wherein the heat-dissipating plate provides therein a concave space, and the filter module is received in the concave space and detachably mounted on the heat-dissipating plate.

45 citations


Patent
N. Matsuura1, Kazuyuki Sakiyama1
16 Dec 1999
TL;DR: In this article, an antenna duplexer is reduced in size, so that a dual-band/triple-band mobile radio terminal small in size and light in weight is realized.
Abstract: An antenna duplexer is reduced in size, so that a dual-band/triple-band mobile radio terminal small in size and light in weight is realized. An off-set PLL modulation system is adopted, and a transmitting system of the antenna duplexer is constituted by switches. Further, in mounting an SAW filter, a multi-layer substrate is adopted, matching circuits and so on are formed by lumped-constant circuit elements, and the SAW filter is received in a space provided on the multi-layer substrate.

Journal ArticleDOI
TL;DR: A second order bandpass filter was designed by converting a conventional bipolar junction transistor-based log-domain filter circuit to its weak-inversion CMOS equivalent, but the integrated circuit at times self-biased to an unintended operating point, rendering the circuit useless.
Abstract: A second order bandpass filter was designed by converting a conventional bipolar junction transistor-based log-domain filter circuit to its weak-inversion CMOS equivalent. When biased as designed, the filter performed as expected, but the integrated circuit at times self-biased to an unintended operating point, rendering the circuit useless. This behavior is related to the positive feedback loops used in log domain (and many other) circuits. Such situations cannot, in general, be predicted by inspection of the circuit topology. A method is presented for predicting and analyzing multiple operating points in SPICE circuit simulation. Of course, the method's predictions apply only to the circuit as modeled in the simulator. Detailed analysis illustrates that the number of operating points can depend on the modeling of effects (in this case, well-substrate leakage currents) that are often modeled carelessly, if at all.

Journal ArticleDOI
TL;DR: In this paper, a new MOS-C bandpass-low-pass filter using the current feedback operational amplifier (CFOA) was presented, which employs two CFOAs, eight MOS transistors operating in the nonsaturation region, and two grounded capacitors.
Abstract: A new MOS-C bandpass-low-pass filter using the current feedback operational amplifier (CFOA) is presented. The filter employs two CFOAs, eight MOS transistors operating in the nonsaturation region, and two grounded capacitors. The proposed MOS-C filter has the advantage of independent control of Q and /spl omega//sub 0/. PSpice simulation results for the proposed filter are given.

Proceedings ArticleDOI
13 Jun 1999
TL;DR: In this paper, two MM-wave tunable filters using micromachined variable capacitors are presented, one with two-pole lumped elements and the other with 2-pole resonators.
Abstract: Novel types of MM-wave tunable filters using micromachined variable capacitors are presented. In order to demonstrate this concept, two bandpass filters, one with 2-pole lumped elements and the other with 2-pole resonators are designed at Ka-band and fabricated using MEMS technology. With applied bias, the center frequency shifts as much as 1.1 GHz (4.2%) at 26.6 GHz, and 0.8 GHz (2.5%) at 32 GHz, was measured for lumped elements and resonators filter, respectively. These results show the potentials of micromachined tunable filters for low cost, highly integrated transmitter and receiver for MM-wave multi-band communication systems.

Patent
03 Mar 1999
TL;DR: In this paper, a test structure for measuring on-wafer impedances is described, which can be used to accurately measure onwafer impedance, such as parasitic capacitances inside active devices such as Field Effect Transistors or the capacitance of interconnect lines with either the substrate or with each other.
Abstract: A novel test structure is described which can be used to accurately measure on-wafer impedances. For example, accurate measurements of the parasitic capacitances inside active devices such as Field Effect Transistors or the capacitance of interconnect lines with either the substrate or with each other can be made. The test technique involves frequency sweep S-parameter power measurements made in the range of 50 MHz to about 20 GHz. One or more identical copies of the DUT are connected on the wafer with one or more on-wafer inductances which are usually lumped, to form a two port circuit. The circuit is essentially a filter operating in the frequency range of 50 MHz to 20 GHz. Although filter circuits are normally designed to provide a flat response in the pass and stop bands, with as sharp a skirt as possible, the objective in designing this test circuit is to design a filter response with sharp inflection points that are uniquely dependent on the reactances that comprise the filter circuit. The primary focus during design is to pre-estimate the impedance (e.g. capacitance) of the DUT, and to design the on-wafer inductances used in the circuit such that the frequency response has sharp peaks and valleys, which are easily identified from measurement. In this way the frequencies of the peaks and valleys can be accurately measured. The measured frequency response is then compared to a model of the circuit.

Journal ArticleDOI
TL;DR: In this paper, the Dominant harmonic active filter (DHAF) based on square-wave inverters is proposed to cost-effectively meet IEEE 519 harmonic current limits for 12-pulse rectifier loads.
Abstract: Harmonic filtering is required for 12 pulse rectifier-utility interface to meet IEEE 519 harmonic current limits. Passive filter techniques employ tuned L-C filters at dominant 11th and 13th harmonic frequencies. However, they also require 5th and 7th tuned filters to avoid series and parallel resonance conditions. State of the art active filtering solutions require high bandwidth and relatively large rating PWM inverters for harmonic filtering of 12 pulse rectifier loads. Thus existing passive and active harmonic filtering solutions are not cost-effective for high power 12 pulse rectifier loads. Dominant harmonic active filter (DHAF) based on square-wave inverters is proposed to cost-effectively meet IEEE 519 harmonic current limits for 12 pulse rectifier loads. The proposed DHAF system employs square-wave inverters switching at 5th and 7th harmonic frequencies, which are transformer coupled in series with 11th and 13th passive filters respectively. The square-wave inverters are controlled to provide 'harmonic isolation' between the supply and load at 5th and 7th harmonic frequencies. The square-wave inverters are rated 1%-2% of the load kVA rating. The proposed DHAF system eliminates the need for large kVAR rated and bulky 5th and 7th passive filters, delivers superior harmonic filtering performance, and provides cost-effective harmonic filtering solution. Simulation results are given to validate the 'harmonic isolation' feature at 5th and 7th harmonic frequencies, and also demonstrate harmonic filtering required to meet IEEE 519 harmonic current limits.

Journal ArticleDOI
TL;DR: Because of small capacitance values the filter circuit is suitable for realization on a single VLSI chip using the CMOS technology, and enables the user to implement the circuit on implantable biotelemetric applications.

Patent
29 Oct 1999
TL;DR: In this article, the error signal is used to update the equalizer filter coefficients instead of using the error signals to correct the RBS effect in the output signal, which can be seen as an indication that the reference signals or reference levels are accurate.
Abstract: Bias control systems, methods, and computer program products generate an error signal that corresponds to a difference between a reference signal and an equalizer output signal. The error signal is then filtered using a first filter circuit to generate an error signal average. If the absolute value of the error signal does not exceed a suitable threshold that is proportional to the error signal average, then the error signal is coupled to the equalizer for use in updating the filter coefficients. Furthermore, a second filter circuit may be used to generate an average of selected equalizer output signal samples. If the absolute value of the error signal is greater than the threshold that is proportional to the error signal average, then the reference signal is updated to correspond to the average of selected equalizer output signal samples. Large errors are interpreted as resulting from inaccurate reference signals or reference levels. The reference signals or reference levels may be inaccurate due to the effects of digital impairments in the network, such as RBS, exhibited in the equalizer output signal. Rather than using the error signal to update the equalizer filter coefficients, the reference signal or reference level is updated to correspond to the average of selected equalizer output signal samples. Conversely, small errors are interpreted as an indication that the reference signals or reference levels are accurate and do not require additional refinement. In this case, the error signal is used to update the equalizer filter coefficients.

Proceedings ArticleDOI
01 Jul 1999
TL;DR: In this paper, the authors proposed a parallel hybrid active filter topology, where the active filter is connected to the passive filter inductor in parallel through a matching transformer with the aim of reducing the current rating of the inverter.
Abstract: Conventional parallel hybrid active filters suffer from the problem of heavy current ratings of devices used in the inverter. In general, this problem has been solved by adjusting the turn ratio of a matching transformer. However, adjusting the transformer to a high turn ratio may not be possible for high voltage power systems due to their requirements for high voltage insulation. In this paper, a new configuration is proposed for a parallel hybrid active filter. In the proposed hybrid active filter, the active filter is connected to the passive filter inductor in parallel through a matching transformer with the aim of reducing the current rating of the inverter. As a result, the fundamental component of the current flowing through the passive filter is divided by the parallel paths of two inductors located at the inverter side and passive filter side, respectively. Hence, the current rating of the inverter can be reduced. Additionally, a harmonic elimination method is suggested for the proposed active filter. Through computer simulations and experiment, we have verified the effectiveness of the proposed topology.

Journal ArticleDOI
TL;DR: In this article, a photonic signal processor topology is presented, which achieves high-Q value microwave bandpass filtering by means of a small free spectral range passive filter, while still operating the active stage with a large gain margin.
Abstract: A new photonic signal processor topology is presented, which achieves high-Q value microwave bandpass filtering. It significantly increases the Q by means of a small free spectral range passive filter, while still operating the active stage with a large gain margin. The filter response demonstrates very high resolution microwave signal filtering with a measured Q value of 983.

Patent
Luan Vu1
16 Dec 1999
TL;DR: In this paper, a band-gap filter circuit is proposed for use in a voltage regulator, where a capacitor charger (or "cap charger") circuit quickly charges a filter capacitor when power is applied to the voltage regulator circuit.
Abstract: A band-gap filter circuit is disclosed for use in a voltage regulator. A capacitor charger (or “cap charger”) circuit quickly charges a filter capacitor when power is applied to the voltage regulator circuit. At start-up, the cap charger begins charging the filter capacitor. Once an output node equals or nearly equals the voltage at the input node, the cap charger shuts off. The circuit provides a very fast turn-on time, reaching 95% of its steady state value within 200 microseconds, thus overcoming the long turn-on times associated with other designs. The present invention may be utilized in power sensitive applications, such as cellular telephones, that wish to shut off the voltage regulator in order to conserve power.

Journal ArticleDOI
TL;DR: In this article, several high-order all-fiber birefringent filters were built by using of Sagnac interferometer and the corresponding architecture theory for these kinds of filters is proposed and verified in experiments.
Abstract: Several high-order all-fiber birefringent filters were built by using of Sagnac interferometer. These filters included the narrow bandpass filter, the narrow bandstop filter, the rectangular filter, and the triangular filter. All these filters can be changed into each other by adjusting only the wave plates inside the Sagnac loop. The corresponding architecture theory for these kinds of filters is proposed and verified in experiments.

Proceedings ArticleDOI
13 Jun 1999
TL;DR: In this paper, a planar bandpass filter made from high temperature superconductors (HTS) is proposed, where coupling between adjacent resonators is provided by "disturbing" the resonator symmetry.
Abstract: The concept and latest experimental results for planar bandpass filters made from high temperature superconductors (HTS) are reported. In the proposed approach, coupling between adjacent resonators is provided by "disturbing" the resonator symmetry. This allows the realization of very narrowband filters with closely spaced resonators. Furthermore, filter parameters can be trimmed in a much wider range (including sign of coupling) then in conventional structures. Results for several quasi-elliptic filters for mobile communication base stations are presented.

Proceedings ArticleDOI
14 Mar 1999
TL;DR: In this paper, a new type of hybrid active filter to compensate harmonics of a nonlinear load is presented, where a series inductor between both the filters is introduced to create a harmonic voltage source at the input of nonlinear loads.
Abstract: A new type of hybrid active filter to compensate harmonics of a nonlinear load is presented in this paper. The proposed topology of hybrid filter combines a shunt passive filter (PF) and a shunt active filter (AF). A series inductor between both the filters is introduced to create a harmonic voltage source at the input of nonlinear load. A diode bridge rectifier with R-C load is considered as a nonlinear load. An indirect current controlled voltage source inverter (ICC-VSI) is considered as an AF. A simple control algorithm based on proportional plus integral control of a self-supporting DC bus voltage of the shunt AF is implemented on a TMS320C31 DSP. The passive filter is tuned to compensate 5/sup th/ and 7/sup th/ harmonics, while the AF compensates the rest of harmonics of the load current. A laboratory prototype model of the proposed hybrid filter is developed and its performance is examined. Experimental results are given and discussed.

Proceedings ArticleDOI
27 Jun 1999
TL;DR: In this paper, an active ripple filter is proposed to suppress the ripple current and EMI generated by the power stage of a power converter, thus reducing the passive filtration requirements.
Abstract: An active ripple filter is an electronic circuit which cancels or suppresses the ripple current and EMI generated by the power stage of a power converter, thus reducing the passive filtration requirements. This paper presents the design and evaluation of a feedforward active ripple filter which employs a Rogowski coil for ripple current sensing. The design of the active filter is discussed in detail, including the advantages, tradeoffs, and limitations of the approach. Experimental results from a prototype converter system using this approach are presented, and quantitative comparisons are made between a hybrid passive/active filter and a purely passive filter. It is demonstrated that substantial improvements in filter mass and converter transient performance can be achieved using the proposed active ripple filtering method.

Patent
25 Feb 1999
TL;DR: In this paper, a modular thin film, distributed, lumped element band-pass filter is presented, where component defining depositions are arranged to overlap and couple to one another with connecting vias.
Abstract: A modular thin film, distributed, lumped element band-pass filter. The filter circuitry is configured on a number of ceramic substrates. The component defining depositions are arranged to overlap and couple to one another with connecting vias. Alternative 800 MHz and 1.9 GHz band-pass filter circuits are disclosed. Bordering ground conductors and covering ground planes shield lumped impedance resonator and overlapping capacitor elements. The layers are configured to accommodate a range of frequencies and permit pre-fabrication with subsequent laser trimming, assembly and packaging.

Patent
30 Nov 1999
TL;DR: In this paper, the authors proposed a solution to adjust the passing bandwidth of the resonator type surface acoustic wave filter by connecting capacitors to those respective resonators in series to reduce and adjust the bandwidth.
Abstract: PROBLEM TO BE SOLVED: To adjust the passing bandwidth of the resonator type surface acoustic wave filter. SOLUTION: Serial arm elements 30S-1, 30S-23, and 30S-4 pass signals of frequencies above a resonance frequency and below an antiresonance frequency well and do not pass frequencies above the antiresonance frequency well. Parallel arm elements 30P-12 and 30P-34 pass frequencies above the resonance frequency and below the antiresonance frequency well and do not pass frequencies below the resonance frequency well. Consequently, this resonator type SAW filter pass signals of frequencies from the resonance frequency of the parallel arm elements 30P-12 and 30P-34 to the antiresonance frequency of the serial arm elements 30S-1, 30S-23, and 30S-4 to serve as a band-pass filter. A piezoelectric substrate 31 has a large electromechanical coupling coefficient, so the bandwidths of serial arm resonators 40S-1, 40-S-23, and 40S-4 and parallel arm resonators 40P-12 and 40P-34 become unnecessarily wide. Therefore, capacitors 50S-1, 50S-23, 50S-4, 50S-12, and 50P-34 are connected to those respective resonators in series to reduce and adjust the bandwidth.

Patent
Kamran Sharifi1
14 Dec 1999
TL;DR: In this paper, an electronic filter has an input connector adapted for electrical connection to a complementary output connector of an asymmetrical digital subscriber line, the output connector has an output voltage node for providing electrical output signals from the electronic filter.
Abstract: An electronic filter has an input connector adapted for electrical connection to a complementary output connector of an asymmetrical digital subscriber line. The input connector has an input voltage node for providing electrical input signals to the electronic filter. Similarly, the filter has an output connector adapted for electrical connection to a complementary input connector of a data receiving device. The output connector has an output voltage node for providing electrical output signals from the electronic filter. The filter selectively passes frequency components of the electrical signals, frequency components below a predetermined corner frequency passing from the input connector to the output connector, frequency components above the predetermined corner frequency not passing from the input connector to the output connector.

Patent
Bradley K. Davis1
30 Nov 1999
TL;DR: In this paper, a method for automatically tuning a filter circuit to compensate for variations in process, voltage, and temperature is presented, where the calibration circuitry is coupled to the tuning circuitry for tuning the capacitor array and is configured to sequentially tune the capacitors in response to the output signal by determining and setting a data bit value for each of the N capacitors.
Abstract: Disclosed are a circuit and a method for automatically tuning a filter circuit to compensate for variations in process, voltage, and temperature. The filter circuit includes one or more N-bit capacitor arrays. The circuit includes calibration circuitry and tuning circuitry. The calibration circuitry includes a resistor and a capacitor array that has at least N capacitors, which are configured to receive N input data bits. Each of the at least N capacitors is associated with an input data bit. The calibration circuitry is configured to integrate an input voltage signal in response to the input data bits to generate an output signal for tuning each of the capacitors. The tuning circuitry is coupled to provide the input data bits to the calibration circuitry for tuning the capacitor array and is configured to sequentially tune the N capacitors in response to the output signal by determining and setting a data bit value for each of the N capacitors. The tuning circuitry provides the tuned data bit value to the associated capacitor for tuning the other remaining capacitors. When all data bits have been tuned, they are provided to the filter circuit to compensate for variations in process, voltage, and temperature.

Patent
04 Jun 1999
TL;DR: In this article, a plurality of inductors are connected in series in a first leg of a balanced line configuration of filter, a second plurality of induction connections are connected as cross branches between terminals of the inductors, and the bypass switches are disposed in a set of connectors for bypassing voice signals around corresponding ones of the cards.
Abstract: An arrangement of plural filter circuits on a single card, and interconnection and mouthing of numerous cards on a single rack to facilitate maintenance, is provided for use in a telco. In each of the filter circuits, there is a first plurality of inductors connected in series in a first leg of a balanced line configuration of filter, a second plurality of inductors connected in series in a second leg of the balanced line configuration of filter, and a plurality of capacitors connected as cross branches between terminals of the inductors. A substrate supports the capacitors and the inductors, wherein each of the inductors is a toroidally wound inductor comprising a toroidal core of magnetic saturation inhibiting material. The saturation inhibiting core material allows reduction in size of a cross-sectional dimension of the core to approximately the cross-sectional dimension of one of the capacitors. For telco equipment, a set of connectors is mounted in a back plane of an enclosure for receiving the cards, and a plurality of bypass switches are disposed in the set of connectors for bypassing voice signals around corresponding ones of the cards. The bypass switches are placed in a state of conduction upon removal of a corresponding one of the cards from the set of connectors.