Abstract: This disclosure provides active power filter methods and apparatus to control the PF, harmonics and/or ripple current associated with powering electrical devices. According to one exemplary aspect, an active power filter is configured to measure the momentary ac line output current, measure the momentary ac line input current and switch an energy buffer to provide additional current to the ac line output or draw current from the ac line input to control the PF associated with the device.

Abstract: Provided is a loop filter which receives first and second currents whose current ratio is n (where n is a natural number). The loop filter includes a first-order filter path, a second-order filter path, and a third-order filter path. The first-order filter path includes an operational amplifier generating an output impedance by increasing by as much as n times an impedance of a second input node to which the second current is applied. The first-order filter path performs a first-order filtering on the first current applied to a first input node by using the operational amplifier. The second-order filter path performs a second-order filtering on the first current applied to the first input node. The third-order filter path performs a third-order filtering on the first current applied to the first input node.

Abstract: An EMC active filter capable to maintain a low earth leakage current at all times, thus being compatible with RCD devices. The filter of the invention has an especially simple inductor's structure, where typically the power conductors pass straight through the filter, without windings, and most of the components can be implemented in a modular shunt circuit. Preferably the filter is realized by connecting the shunt module by an IDC device to the phase conductors, or directly to the line and load terminal, thus avoiding cutting and splicing high-current cables. The particular protection circuit of the filter prevents in-rush current at power on, and limits earth leakage current even in case of a fault in the line.

Abstract: An active analog filter (700, 1000) having a MOS capacitor device (730, 1030) with improved linearity is proposed. In an exemplary embodiment, dc bias voltage sources (755, 745) alter the capacitance of MOS varactors (740, 750) connected in anti parallel so that the total capacitance of the MOS capacitor device remains constant or within a range over the voltage range of the filter and the filter linearity is set. In a further exemplary embodiment the output stage (1070) of the operational amplifier circuit (1020) of the active analog filter (1000) is modified so that the dc bias voltage is provided by resistors (1055, 1045) connected to a current source (1060) already existing in the filter. Thus the linearity is set and the die area is significantly reduced.

Abstract: An active low-pass current filter apparatus and method reduces conducted emissions above a predefined cutoff frequency at high power levels. The apparatus and method use a bidirectional DC-DC converter to minimize current fluctuations on a power lead that may result in conducted emissions above the predefined cutoff frequency. The bidirectional DC-DC converter absorbs current from the power lead and feeds current to the load lead as needed to compensate for the current fluctuations on the power lead. Power to the DC-DC converter is provided by a separate auxiliary power source. A monitoring circuit compares the voltage level of the auxiliary power source to a reference voltage and compensates for variations in the voltage level of the auxiliary power source without interfering with the suppression of the conducted emissions.

Abstract: The present invention discloses a circuit for settling DC offset and controlling RC time-constant in a direct conversion receiver. The circuit includes a variable resistive unit for providing a continuously or non-continuously variable resistance in the direct conversion receiver. The variable resistive unit can provide the variable resistance by utilizing a controllable transistor or a plurality of resistors. Accordingly, the variable resistive unit can be coupled to a capacitor for constituting a high pass filter, which is capable of rapidly settling DC offset in a direct conversion receiver.

Abstract: A design structure for intrinsic RC power distribution for noise filtering of analog supplies. The design structure is embodied in a machine readable medium for designing, manufacturing, or testing an integrated circuit. The design structure includes a voltage regulator; a variable resistor coupled to the voltage regulator; and a performance monitor and control circuit providing a feedback loop to the variable resistor.

Abstract: A method of reconstruction of a fault-reduced voltage signal corresponding in frequency, amplitude and phase position to a sinusoidal input voltage fault-prone in frequency, amplitude and/or phase position is provided. The input voltage is fed to a first band-pass filter including an adjustable resonant frequency and amplification, the output voltage being the fault-reduced voltage signal. A controlled variable is determined for a first controller by determining the scanned differential voltage of the output voltage and the input voltage in zero points of the output voltage, the controller adjusting the resonate frequency of the first band-pass filter such that the differential voltage in the zero points disappears.

Abstract: A circuit arrangement having a signal input configured to be supplied with a voltage signal; a first operational transconductance amplifier (OTA) having a voltage input that may be coupled to the signal input; at least one second OTA having a voltage input that may be coupled to the signal input; and at least one output capacitor which may be coupled to an output of the first OTA and to an output of the at least one second OTA, wherein an identical potential is set at the outputs of the first OTA and of the at least one second OTA.

Abstract: An active poly-phase filter has a converting section and a filtering section having two first input terminals, two second input terminals and four output terminals. The converting section has first, second, fourth and fifth transistors forming a translinear circuit and a third transistor forming a current mirror circuit with the second transistor. The converting section converts unbalanced high-frequency power into a difference input between a collector current of the third transistor and a collector current of the first transistor having phase difference of ? radians. The filtering section receives one collector current at the first input terminals and receives another collector current at the second input terminals and outputs a first difference output between outputs of two output terminals and a second difference output between outputs of other two output terminals such that the difference outputs has a phase difference of ?/2 radians.

Abstract: Embodiments of the present invention relate generally to reconstruction filtering. In particular, embodiments enable highly linear, highly programmable, and easily reconfigurable reconstruction filters. Further, embodiments provide substantial power consumption, area, and cost savings compared to conventional solutions. For example, embodiments use all-passive filtering and substantially reduce active elements compared to conventional solutions. As a result, significant reductions in required area, noise, and power consumption can be achieved. In addition, embodiments perform filtering solely in the current domain, thereby eliminating the non-linear voltage-to-current conversion used in conventional circuits and enabling highly linear filtering. Furthermore, embodiments are highly programmable and easily reconfigurable without the use of tunable capacitors. As such, embodiments are very suitable solutions for multi-band multi-mode wireless transmitters.

Abstract: The present invention discloses a method, apparatus and system for obtaining the tuning capacitance of a Gm-C filter. The method includes: integrating a simulated capacitor within a given time via a current, where the simulated capacitor simulates the capacitor of the Gm-C filter which is set to an even capacitor array; and comparing the integral voltage obtained by the integration with the reference voltage, finding a simulated capacitance that makes the integral voltage equal to the reference voltage via gradual approaching by adjusting a control code, and determining the simulated capacitance as the tuning capacitance. The present invention improves the performance of a Gm-C filter without affecting the performance of the Gm-C filter.

Abstract: The device described herein proposes an electronic active filter void of capacitors and inductors. The circuit utilizes only operational amplifiers (OP-Amp) and resistors, hence the name Op-R. Although capable of being constructed of lumped circuit elements this filter is intended for integrated circuit (IC) applications. Filtering of signals can be accommodated from dc through the UHF frequency range depending on the selected op-amp ICs. Low pass, band pass, high pass, as well as band reject frequency responses are achievable. Although the circuits described herein are single input-single output, multiple inputs and outputs present no difficulty, being limited only chip space. Temperature and production spread variations are also considered within the realm of tunability.

Abstract: A method and apparatus is provided for reducing interference in circuits. A management strategy is provided to reduce reference spurs and interference in circuits. The management strategy uses a combination of one or more techniques which reduce the digital current, minimize mutual inductance, utilize field cancellation, prevent leakage current, and/or manage impedance. These techniques may be used alone, or preferably, used on combination with one another.

Abstract: Circuits, methods and devices for providing low-pass filtering are implemented according to a number of different embodiments. In one such embodiment a Sallen-Key low-pass filter circuit is implemented that comprises a first resistor and a second resistor connected in series, the first resistor being connected between the second resistor and an input of the circuit. The second resistor is directly connected between the first resistor and an output of the circuit.

Abstract: The present disclosure describes methods and apparatus for compensating DC offset in a filter having a plurality of transconductance pieces. In one implementation, the method includes measuring a corresponding DC offset associated with each transconductance piece of the plurality of transconductance pieces; storing each measured DC offset corresponding to each transconductance piece of the plurality of transconductance pieces; selecting one or more of the plurality of transconductance pieces to be used during operation of the filter; deriving an aggregate amount of DC offset for the one or more selected transconductance pieces, the aggregate amount of DC offset being derived based on each stored DC offset value corresponding to each selected transconductance piece; and applying the derived aggregate amount of DC offset to the one or more selected transconductance pieces to compensate for the DC offset during the operation of the filter.

Abstract: A current filter circuit is provided. The current filter circuit comprises a source transistor comprising a drain, a gate, and a source. The source of the source transistor is coupled to a reference voltage terminal, the gate of the source transistor is coupled to the gate of a mirror transistor, and the drain of the source transistor is coupled to a reference current source. The mirror transistor comprises a drain, a gate, and a source. The source of the mirror transistor is coupled to the reference voltage terminal, the gate is coupled to the gate of the source transistor, and the drain is coupled to a load. The current filter circuit comprises a low pass filter for filtering noise. The current filter circuit also comprises an impedance reduction circuit coupled to the drain of the mirror transistor for reducing bandwidth of the current filter circuit.

Abstract: An offset free sinc interpolating filter includes differentiators operating at a first sampling frequency, integrators operating at a second sampling frequency and one or more coefficient multipliers. The coefficient multipliers multiply a received value with a constant coefficient value to generate an output value. The differentiators, integrators and coefficient multipliers can be operatively coupled to each other, either directly or through other components such as adders and delay elements, or by a combination of the two. In operation, an input signal is provided to the sinc interpolating filter at the first sampling frequency. The input signal is processed by the differentiators, integrators and coefficient multipliers to generate an output signal at the second sampling frequency. Once the output signal is generated, the integrators are reset before the next input cycle begins.

Abstract: A continuous-time filter system comprises a master control unit and a slave unit with one or more slave filters. The master control unit includes an integrator having circuit elements which match those elements of the slave filter that define the slave filter's time constant. The master control unit further includes a voltage comparator connected to an output of the integrator, the voltage comparator providing an output frequency signal, and a phase frequency comparator providing a control signal as an output signal, the phase frequency comparator receiving said output frequency signal and a reference frequency signal as input signals. The slave unit includes said at least one slave filter, the slave filter having a control signal input for receiving said control signal thus allowing to calibrate the slave filter's transfer function by influencing the slave filter's time constant.

Abstract: Exemplary embodiments of the invention disclose receiver baseband filtering. In an exemplary embodiment, the filter device may comprise a continuous-time filter and a discrete-time filter operably coupled to the continuous time-filter. The discrete-time filter may include a passive infinite impulse response filter operably coupled between the continuous-time filter and an amplifier. The discrete-time filter may also include an active infinite impulse response filter operably coupled between an output of the amplifier and an input of the amplifier. The discrete-time filter may be configured to combine an output of the active infinite impulse response filter and an output of the passive infinite impulse response filter to form a composite signal. Furthermore, the amplifier may be configured to receive and amplify the composite signal.

Abstract: A network filter includes at least one X capacitor located between two supply lines and at least one discharge resistor that discharges the X capacitor, wherein the discharge resistor is arranged in series with at least one switching element, and at least one detector circuit that recognizes a network disconnection and closes the switching element to discharge the X capacitor via the discharge resistor when a network disconnection is recognized.

Abstract: Methods and apparatus to fine gain and/or phase adjustment of analog quadrature filters are described. In one embodiment, gain and/or phase of an analog quadrature filter may be digitally controlled by switching one or more resistors coupled to the quadrature filter. Other embodiments are also described.

Abstract: An embodiment is directed to a zero IF down converter circuit. The circuit comprises a voltage-to-current converter, a mixer, and a suppression circuit. The voltage-to-current converter converts an RF voltage signal to an RF current signal. The mixer changes the frequency of the current signal to a lower frequency current signal. The suppression circuit removes a lower frequency distortion component from the RF current signal before sending the RF current signal to the mixer.

Abstract: A circuit includes a first filter comprising a first inductor coupled to a first variable capacitor, wherein the first filter is associated with a first resonant frequency. The circuit further comprises an amplifier coupled to the first filter and a second filter coupled to the amplifier. The second filter comprises a second inductor coupled to a second variable capacitor, wherein the second filter is associated with a second resonant frequency that is substantially the same as the first resonant frequency. At least a portion of the first filter and at least a portion of the second filter are formed on an integrated circuit.

Abstract: An integrated circuit includes a signal-path filter, a high-pass filter, and a control circuit. The signal-path filter is configured to receive an input signal and provide an output signal. The high-pass filter is coupled to the signal-path filter and is configured to reduce a direct-current (DC) component of the input signal. The high-pass filter includes a metal-oxide-semiconductor (MOS) switch, wherein a corner frequency of the high-pass filter is based on a resistance of the MOS switch. The control circuit is configured to provide a control voltage to the MOS switch. The control circuit includes a reference resistor, wherein the resistance of the MOS switch substantially tracks the resistance of the reference resistor. The integrated circuit may be embodied in software and/or included in a device (e.g., a mobile telephone) that receives and filters a signal.

Abstract: A filtering arrangement comprises a reference voltage input (1) and a compensation current arrangement (10) coupled to the reference voltage input (1) and configured to provide a control current at a current output (2) as a function of a voltage at the reference voltage input (1). The filtering arrangement also comprises a first and a second current source (20, 30) each having a control input (4, 5) coupled to the current output (2), a first and a second filter input (7, 8), and a first transistor (T1) and a second transistor (T2). The first transistor (T1) has a first connection (T11), a second connection (T12) and a control connection (T1c), where its first connection (T11) is coupled to the first current source (20) and its second connection (T12) is coupled to the first filter input (7) through a first resistor (R1).

Abstract: In an embodiment, an apparatus and method reduces a calibration settling time in an analog-to-digital converter (ADC). The ADC has a reference voltage supply. The reference voltage supply has an output. A filter capacitor is coupled to the reference voltage supply output. An isolation transistor is series-coupled between the filter capacitor and ground. The isolation transistor isolates the filter capacitor during calibration of the ADC.

Abstract: A plurality of low-pass filters (2-1, 2-2, 2-3) are cascaded to the post stage of an OTA (1) and a plurality of high-pass notch filters (3-1, 3-2, 3-3) are cascaded further to the post-stage thereof so that a high-pass filter having a Q is not connected to the output of the OTA (1) having a high output impedance and a capacitor having a low capacitance is not connected with the output of th OTA (1) thus preventing multifeedback and avoiding such problems as the zero point of the notch filter (BEF) deviates from a design value or oscillation takes place.

Abstract: In one embodiment, an apparatus includes an upconversion unit configured to upconvert a baseband signal to a radio frequency (RF) signal. A plurality of baluns for a plurality of wireless bands are provided. Multiplexing circuitry is coupled to the plurality of baluns where the upconversion unit is coupled to each balun through the multiplexing circuitry. The multiplexing circuitry is configured to multiplex the radio frequency signal from the upconversion unit to one of the plurality of baluns based on a wireless band being used.

Abstract: An AC noise filter designed to filter the small amplitude AC noise of all frequencies by using inline reverse coupled parallel PN semiconductors which offer a high resistance to AC voltages of less than a diode voltage drop. Inline reverse coupled parallel PN semiconductors are used in the AC power line-side as well as in the neutral-line side. For additional AC noise filtering, capacitors are coupled across the AC or DC power source input and at the output to the AC or DC user. For the AC power, IEC connectors are used at the input and output for worldwide use.

Abstract: It is possible to provide a voltage-current converter which can realize a variable filter having a steep cut-off characteristic with a small area. The voltage-current converter includes: one or more sampling/holding units for sampling an inputted voltage and holding the sampled voltage; one or more separate voltage-current conversion units for outputting a current corresponding to the voltage held by the sampling/holding units; and a control unit for controlling the timing of the sampling and holding of the inputted voltage by the sampling/holding units.

Abstract: An integrating amplifier on an IC, which comprises a feedback loop using an external device as an integrating capacitor, has added a second feedback loop that provides an additional current to the input of the amplifier, which current can be used to increase the input range of the charge that can be measured without needing another external capacitor or pad.

Abstract: Systems and methods for filtering analog signals corresponding to sensed parameters are provided. In this regard, a representative method includes: sampling the analog signal to acquire a sequential series of data points; determining a first cumulative change in value with respect to a first of the data points relative to at least two subsequent data points in the series, the subsequent data points including a second of the data points; determining a second cumulative change in value with respect to the second of the data points relative to at least two data points adjacent to the second of the data points in the series, the at least two adjacent data points including an immediately preceding and an immediately succeeding one of the data points relative to the second of the data points; comparing the first cumulative change and the second cumulative change to respective data thresholds; and outputting a filtered analog signal based, at least in part, on results of the comparing.

Abstract: A high pass filter chip with a large size capacitor is disclosed. The high pass filter chip includes a fully-differential sensing device circuit. The fully differential sensing device circuit includes a first amplifier circuit, a second amplifier circuit, and a miller capacitor module including a third amplifier. The first amplifier circuit includes a first transistor and a second transistor, in which the base of the first transistor is coupled to the base of the second transistor. The second amplifier circuit includes a third transistor and a fourth transistor, in which the base of the third transistor is coupled to the base of the fourth transistor. A first input terminal of the third amplifier is coupled to the base of the second transistor of the first amplifier circuit, and a second terminal of the amplifier is coupled to the base of the third transistor of the second amplifier circuit.

Abstract: According to one embodiment of the invention, a programmable finite impulse response (FIR) filter is implemented with differential isolation circuits to isolate parasitic capacitance from attenuating an output signal at both a first and second differential output terminals of the FIR filter. The FIR includes a summing circuit that provides operational advantages to the FIR filter.

Abstract: An operating circuit includes an amplifier having a first input terminal coupled to a reference voltage; a first transconducting element for selectively generating a first current; a second transconducting element for selectively generating a second current; a resistive element having a first terminal coupled to the first transconducting element; a capacitive element having a first terminal selectively coupled to the second transconducting element; and a switching device. The switching device has a first configuration to connect the first terminal of the capacitive element to the second transconducting element and connect the first terminal of the resistive element to a second input terminal of the amplifier, and has a second configuration to disconnect the first terminal of the capacitive element from the second transconducting element and connect the second input terminal of the amplifier to the first terminal of the capacitive element instead of the first terminal of the resistive element.

Abstract: Filter circuit includes Nth-order active filters switching circuit which switches shorting or non-shorting of active filter, and power-supply control circuit which controls such that a power supply of active filter is turned off when switching circuit shorts active filter. A receiver employing filter circuit turns off the power supply of active filter not needed when no interference wave exists within a given range from a desired frequency band. The foregoing structure allows lowering the power consumption of filter circuit.

Abstract: A preselector amplifier system and method including of various components is described. The various components may include a vector generator, an active power splitter, an active power combiner, or the like. The preselector amplifier may be integral to and/or coupled to a communications system. The communications system may be at least one of a transceiver, receiver and/or transmitter. The communications system may transmit radio frequency (RF) signals.

Abstract: The present invention is a receiving circuit used for a cellular phone that is reduced in size and can realize low power consumption. In a signal reception circuit that is used in a cellular phone that perform transmission and reception of a plurality of band wireless signals and includes a low-pass filter for removing blockers unnecessary for signal reception, the low-pass filter 104 is composed of a plurality of filters composed of a plurality of different circuit configurations and having a plurality of different pole positions, switching between a filter for blocker removal and a filter configuration with reduced sensitivity degradation is performed by combining a plurality of filters for each signal reception band, and by performing power-off of an unnecessary filter portion in the filter configuration, power consumption is reduced.

Abstract: A processing apparatus for calibrating an analog filter of a communication device in a digital domain is disclosed, wherein the analog filter is arranged to perform a filtering operation upon a communication signal in an analog domain. The processing apparatus includes a signal processing circuit and a digital filter. The signal processing circuit is used for transforming the communication signal between the digital domain and the analog domain. The digital filter is coupled to the signal processing circuit, and used for performing a filtering operation upon the communication signal in the digital domain, wherein a frequency response of the digital filter is arranged to compensate a frequency response of the analog filter according to at least a compensation parameter generated with reference to a frequency-related characteristic of the analog filter.

Abstract: A signal filter and accompanying methods. In one embodiment, the filter includes a first mechanism for receiving a first signal. A second mechanism employs one or more modified representations of the first signal to cancel one or more frequency components of the first signal, yielding an output signal in response thereto. In a more specific embodiment, the first mechanism includes a splitter for receiving the first signal and splitting the first signal onto a first path and a second path. The second mechanism further includes one or more delay modules and one or more phase shifters in the first path and/or the second path. One or more controllable amplifiers are optionally included in the first path and/or the second path. The one or more delay modules, phase shifters, or amplifiers are responsive to one or more control signals from a controller. The controller is adapted to modify behavior of the second mechanism so that the filter is characterized by a desired frequency response.

Abstract: An integrated circuit is provided having a system clock and a clock filter. The clock filter has a temperature sensor for sensing a temperature of the integrated circuit and for causing the clock filter to block output of the system clock if the sensed temperature is below or above a predetermined temperature.

Abstract: A digital signal detector detects digital signals by only sensing the rising and falling edges of a received digital signal and latches the logic state between the detected edges. Such edges contain very high frequencies that are much higher than the fundamental frequency of the digital signal train. A small high pass filter filters out at least the DC component and the fundamental frequency of the received digital signal. A filtered edge appears as a spike that goes either positive or negative depending on whether the edge is a rising or falling edge. A memory element, such as comprising an RS flip flop, is triggered by the positive and negative spikes. A positive spike triggers the flip flop to output a logical one, and a negative spike triggers the latch to output a logical zero. In this way, the digital signal is recreated without the original digital signal itself being required to pass through the high pass filter.

Abstract: A power supply circuit for a south bridge chip includes a voltage conversion chip having a first voltage input terminal, a second voltage input terminal, a driving voltage output terminal, and a gate voltage output terminal, a control circuit having a first control terminal, a second control terminal, and an output terminal, and a filter circuit coupled between the control circuit and the south bridge chip. The voltage conversion chip receives a first voltage and a second voltage from a power supply at the first and second voltage input terminals respectively, and outputs driving voltages at the driving voltage output terminal and gate voltage output terminal respectively. The control circuit receives the driving voltages at the first and second control terminals respectively, and outputs a working voltage to the south bridge chip via the filter circuit.

Abstract: Modulation circuits for operating in at least a first and second mode are described herein.

Abstract: This disclosure provides active power filter methods and apparatus to control the PF, harmonics and/or ripple current associated with powering electrical devices. According to one exemplary aspect, an active power filter is configured to measure the momentary ac line output current, measure the momentary ac line input current and switch an energy buffer to provide additional current to the ac line output or draw current from the ac line input to control the PF associated with the device.

Abstract: A technique of improving antialiasing and adjacent channel interference filtering uses cascaded passive IIR filter stages combined with direct sampling and mixing. The methodology and related architecture allows for increased passive IIR filtering without necessitating use of amplifier stages.

Abstract: An active power filter includes an energy storage capacitor, an inverter, a filtering circuit and a controller. The inverter is controlled to act as a virtual resister at a fundamental frequency for compensating for the power loss of the active power filter, to act as a virtual capacitor at a fundamental frequency for compensating for a fundamental reactive power of the load, and/or to generate a harmonic current for suppressing the harmonic currents of specific orders of the load.

Abstract: The joint (36) comprises a tubular body (37) having two connecting zones (38, 39) each connected by an end to a tubular element (40) of a fluid transport line, giving continuity to passage of fluid. The tubular body is made of a mixture of an electrically-conductive material such as PVC, with carbon black to give it electrical conductivity. The joint has an internal surface (41) which is destined to come into contact with the transported fluid, and an external surface which is destined to have a grounded galvanic contact. The joint is inserted in the discharge fluid drainage line of a dialyzer filter, in an apparatus for intensive treatment of acute renal insufficiency, for eliminating ECG artefacts due to functioning of peristaltic pumps in the apparatus.

Abstract: A filtering device based on an active transconductance filter includes auto-calibration means, the principle of calibration consisting in slaving the power supply current for the filter as a function of the phase shift between a second signal shifted by a first predetermined phase shift with respect to a periodic reference signal, and the output signal of the filter in response to a first signal shifted by a second predetermined phase shift with respect to the periodic reference signal, the slaving tending to minimize the phase shift between the output signal of the filter and the second signal.