1061 results about "Band-stop filter" patented technology

A band stop filter is provided for a lead wire of an active medical device (AMD). The band stop filter includes a capacitor in parallel with an inductor. The parallel capacitor and inductor are placed in series with the lead wire of the AMD, wherein values of capacitance and inductance are selected such that the band stop filter is resonant at a selected frequency. The Q of the inductor may be relatively maximized and the Q of the capacitor may be relatively minimized to reduce the overall Q of the band stop filter to attenuate current flow through the lead wire along a range of selected frequencies. In a preferred form, the band stop filter is integrated into a TIP and / or RING electrode for an active implantable medical device.

A band stop filter is provided for a lead wire of an active implantable medical device (AIMD). The band stop filter includes a capacitor in parallel with an inductor. The parallel capacitor and inductor are placed in series with the implantable lead wire of the AIMD, wherein values of capacitance and inductance are selected such that the band stop filter is resonant at a selected frequency. The Q of the inductor may be relatively maximized and the Q of the capacitor may be relatively minimized to reduce the overall Q of the band stop filter to attenuate current flow through the implantable lead wire along a range of selected frequencies. In a preferred form, the band stop filter is integrated into a TIP and / or RING electrode for the active implantable medical device.

A medical lead system includes at least one bandstop filter for attenuating current flow through the lead across a range of frequencies. The bandstop filter has an overall circuit Q wherein the resultant 3 dB bandwidth is at least 10 kHz. The values of capacitance and inductance of the bandstop filter are selected such that the bandstop filter is resonant at a selected center frequency or range of frequencies. Preferably, the bandstop filter has an overall circuit Q wherein the resultant 10 dB bandwidth is at least 10 kHz. Such bandstop filters are backwards compatible with known implantable deployment systems and extraction systems.

The present invention is a hybrid RF-digital signal processor-based filter for multiband radio architectures systems capable of spectrum re-farming and software defined radios. It performs low-loss frequency agile multiple notch filtering at RF where a large dynamic range exists at a filter input between signals in a stopband and passband. It is a frequency dependent signal attenuation apparatus having two paths connected together by directional couplers. The first path comprising a component such as a delay component or duplexer. The second path comprising a bandstop filter connected to a down converter, a digital filter, and an up converter. At the output of a power amplifier, the invention can be used to attenuate spurs, or noise within bands with strict emission constraints. At the input of a low noise amplifier, the invention can be used to attenuate blockers and transmitter noise outside of the receiver passband.

A filter system comprising three or more filters, each having different passbands, and an impedance adjusting network coupled between a filter system ports and each of the ports of at least two of the filters to adjust the port impedances of the filters coupled to the network. The adjusted port impedance of each filter at a frequency representative of at least one of the other filters coupled to the network is at a non-loading level. In one embodiment, the filter system is configured for use in a wireless communication receiver and / or handset.

A distance to PIM measurement circuit is made using a device such as an AWS transceiver that has separate transmit and receive bands. With a typical AWS transceiver placed in close proximity to a PCS transceiver, the AWS device will include a band reject filter to eliminate interference from the PCS signals. The PIM measurement circuit includes two frequency sources F1 and F2 that are provided through a combiner for characterization of the PIM circuit. To enable distance determination, an FM measurement is created by using a offset sweep generator attached to one of the two frequency sources. To avoid frequencies blocked by the band reject filter, a desired harmonic of a test PIM harmonic signal is selected outside the band of the band reject filter. In one embodiment, a reference signal is provided by mixing a signal from an ×M multiplier connected to the F1 source with an ×N multiplier signal connected to the F2 source, the mixed output being filtered to select the desired harmonic reference signal to avoid the band reject filter. In another embodiment, a reference signal is created by generating all harmonics of the combined F1 and F2 signal using a series connected amplifier and clipping diodes with a filter again used to select the desired harmonic reference signal to avoid the band reject filter.

Medical lead systems utilizing electromagnetic bandstop filters are provide which can be utilized in a magnetic resonance imaging (MRI) environment for patients who have implanted medical devices. Such lead systems may be advantageously used in left ventricle cardiac stimulation systems, neuro-stimulation systems, and deep brain electrodes used for the treatment of Parkinson's disease and other movement disorders. The bandstop filters, which include a tuned parallel capacitor and inductor circuit, are backwards compatible with known implantable deployment systems.

A one-piece cylindrical bandstop filter for medical lead systems incorporates parallel capacitive and inductive elements in a compact cylindrical configuration. The compact cylindrical configuration of the bandstop filter does not add significantly to the size or weight of the medical lead system. Preferably, the bandstop filters are of biocompatible materials or hermetically sealed in biocompatible containers. The parallel capacitive and inductive elements are placed in series with the medical lead system, and are selected so as to resonate at one or more selected frequencies, typically MRI pulsed frequencies.

In an adaptive filter for cancelling common-mode noise in digital subscriber loops, a narrowband noise estimator is used to detect one or more noisy frequency bands of the common mode signal and derive therefrom a first noise estimation signal. A wideband noise estimator derives from the remainder of the common mode signal a second noise estimation signal. The first and second noise estimation signals are subtracted from the differential signal, The wideband noise estimator comprises a bandstop filter for removing the frequencies detected by the narrowband noise estimator, an analog-to-digital converter for digitizing the bandstopped signal, and an adaptive filter for deriving the second noise estimation signal from the digitized bandstopped signal and, in the process, compensating for phase and gain differences, especially attributable to the interference being injected at different points along the length of the channel.

An MRI-compatible electronic medical therapy system includes an active medical device connected to a plurality of electrodes. A multiplexer circuit includes at least one circuit protection device in electrical series with the electrodes and the medical device. The circuit protection device can be in the form of a switch or a band stop filter. The circuit protection device is adapted to permit current flow therethrough during normal medical device related therapy, but substantially prevent current flow therethrough in the presence of an induced electromagnetic field.

A hybrid diplex bandstop filter includes a lowpass filter circuit which passes a first range of frequencies and a highpass filter circuit passes a third range of frequencies. The filter blocks a second range of frequencies. The third range of frequencies is higher than the second range and the first range. A tuning circuit tunes at least one re-resonance of a frequency inside the first range of frequencies to either within the second range of frequencies or outside an industry specified upper limit which is in the third range of frequencies.

An absorptive bandstop filter includes at least two frequency-dependent networks, one of which constitutes a bandpass filter, that form at least two forward signal paths between an input port and an output port and whose transmission magnitude and phase characteristics are selected to provide a relative stopband bandwidth that is substantially independent of the maximum attenuation within the stopband and / or in which the maximum attenuation within the stopband is substantially independent of the unloaded quality factor of the resonators. The constituent network characteristics can also be selected to provide low reflection in the stopband as well as in the passband. The absorptive bandstop filter can be electrically tunable and can substantially maintain its attenuation characteristics over a broad frequency tuning range.

An electric damper which does not transmit unbalance wheel vibration to a vehicle body is provided. A low-pass cutoff frequency setting unit and a high-pass cutoff frequency setting unit respectively set the cutoff frequencies for band-stop filters to a frequency band corresponding to unbalance wheel vibration based on a signal indicating a vehicle speed from a vehicle speed sensor, and a function as a band-stop filter comprising a low-pass filter computation unit, a high-pass filter computation unit and an adder is computed for a displacement rate of the vertical motion of a wheel calculated by a differentiating unit in a damper control unit. A damper control amount computation unit calculates a control amount of controlling an electric motor for a motor-driven damper based on the calculated filtered displacement rate, and outputs a control signal to a motor driving unit through a driving circuit output unit.

This invention provides a voltage tunable filter comprising an input connection point, an output connection point, and at least one circuit branch electrically coupled to the input connection point and the output connection point and including a voltage tunable dielectric varactor electrically connected to an inductor. The voltage tunable filter can be one of a low-pass, high-pass, band-pass, or band-stop filter. The varactor can include built-in DC blocking capacitors.

A filter unit comprises a wideband bandpass filter; at least one band-elimination filter having a stop band within the passband of the bandpass filter, so that the passband is divided into a plurality of pass bands by the stop band; and the wideband bandpass filter and the band-elimination filter being disposed in a single dielectric member. Since the passband of a wideband bandpass filter is divided into a plurality of pass bands by stop bands of one or more band-elimination filters, signals having frequencies corresponding to these divided pass bands are able to pass through the filter unit simultaneously.

A method of constructing a band-stop filter comprises designing a band-stop filter including a signal transmission path, resonant elements disposed along the signal transmission path, and non-resonant elements coupling the resonant elements together to form a stopband having transmission zeroes corresponding to respective frequencies of the resonant elements. The method further comprises changing the order in which the resonant elements are disposed along the signal transmission path to create different filter solutions, computing a performance parameter for each filter solution, comparing the performance parameters to each other, selecting one of the filter solutions based on this comparison, and constructing the band-stop filter using the selected filter solution. Another RF band-stop filter comprises resonant elements coupled together to form a stopband, wherein at least two of the resonant elements have third order IMD components different from each other, such that the IMD components are asymmetrical about the stopband.

Medical lead systems utilizing electromagnetic bandstop filters are provide which can be utilized in a magnetic resonance imaging (MRI) environment for patients who have implanted medical devices. The medical lead system includes an implanted lead having at least one bandstop filter associated therewith, for attenuating current flow through the lead over a range of frequencies. The bandstop filter has an overall circuit Q wherein the resultant 3 dB bandwidth is at least 10 kHz. The values of capacitance and inductance of the bandstop filter are selected such that the bandstop filter is resonant at a selected center frequency. Preferably, the bandstop filter has an overall circuit Q wherein the resultant 10 dB bandwidth is at least 10 kHz. Such bandstop filters are backwards compatible with known implantable deployment systems and extraction systems.