Abstract: A method for adjusting parameters of an adaptive equalizer makes use of a transmitted signal received by a receiving end to adjust parameters of an adaptive equalizer. First, signal strengths of a first frequency band and a second frequency band in the transmitted signal are detected. The signal strengths of the first frequency band and the second frequency band are then compared to get a compensation ratio, i.e., the total compensation quantity of the first frequency band to the second frequency band. Finally, the parameter setting of the equalizer is adjusted according to feedback of the compensation ratio. Optimum gain control of the adaptive equalizer can thus be accomplished to compensate signal attenuation to the transmitted signal caused by the channel.

Abstract: A tunable RF filter, comprising: an emitter follower stage (2); and a common emitter stage (4); the common emitter stage (4) providing feedback to the emitter follower stage (2). The common emitter stage (4) may comprise a first transistor (Ti) being the only transistor of the common emitter stage (4); and the emitter follower stage (2) may comprise a second transistor (T2) being the only transistor of the emitter follower stage (2). A further tunable RF filter provides improved linearity, comprising: an emitter follower stage (22); a joint common emitter and emitter follower stage (24); and a gain stage (26); a common emitter output of the joint common emitter and emitter follower stage (24) providing feedback to the emitter follower stage (22), and an emitter follower output of the joint common emitter and emitter follower stage (24) providing an input to the gain stage (26).

Abstract: A filter and a filtering method are provided. The filter includes a first compare voltage generation unit, a second compare voltage generation unit, a comparator and a first inverter. The first compare voltage generation unit generates a first compare voltage according to an input signal. The second compare voltage generation unit generates a second compare voltage. When the first compare voltage is not over the first reference voltage, the second compare voltage equals the first reference voltage. When the first compare voltage is over the first reference voltage, the second compare voltage equals the second reference voltage. The first reference voltage and the second reference voltage depend on a minimum pulse width. The comparator outputs a filtered signal according to the first compare voltage and the second compare voltage. The first inverter inverts a filtered signal to an output signal.

Abstract: A lock-in amplifier with an additional phase-sensitive detector is provided. A measurement signal is mixed in a multiplicative fashion with a reference signal, which is phase-shifted by 90 degrees, for a modulation frequency. In order to reliably filter out interference signal portions in a widest possible dynamic range and, at the same time, minimize unavoidable influence on the useful signal portion, a control device is connected downstream of the additional phase-sensitive detector. The control device determines a control variable corresponding to the strength of the interference signal from the measurement signal mixed with the reference signal phase shifted by 90 degrees and uses the control variable to change the integration duration of the integrator proportionally to the control variable, a corresponding cut-off frequency of an equivalent low pass being coordinated automatically.

Abstract: In one embodiment, the present invention includes an electronic circuit comprising a first stage having a first differential inductive element and a second differential inductive element, and a second stage coupled to an output of the first stage, the second stage having a first differential inductive element and a second differential inductive element, wherein the first and second differential inductive elements of the first stage couple magnetically to generate a first phase error, wherein the first and second differential inductive elements of the second stage couple magnetically to generate a second phase error, and wherein the second phase error cancels the first phase error.

Abstract: A second order analog filter based on transconductance amplifiers and capacitors (gmC) has good linearity at low operating voltage by using linear active transconductance amplifiers with gains determined by physical resistors and output current mirrors in a positive feedback configuration to allow the implementation of complex poles in the transfer function.

Abstract: Disclosed are a circuit and a method for tuning a programmable filter including input terminals, output terminals, a filter network and a transadmittance stage. The input terminals can receive input signals, and the output terminals output a filtered signal. The transadmittance stage, coupled to the input terminals, generates a current at its output based on the input signals. The output of the transadmittance stage can be coupled to the output terminals. The filter network can be a resistive-capacitive network connected to the input terminals. The RC network can include a capacitance respectively coupling the input terminals to output terminals, and a voltage divider network coupling the input and output terminals together. The transadmittance stage output terminals can be connected to the voltage divider, and the output terminals of the programmable filter circuit are coupled to respective intermediate nodes of the voltage divider network to provide a filtered output signal.

Abstract: Analog supply for an analog circuit and process for supplying an analog signal to an analog circuit. The analog supply includes a noise filter having a variable resistor, and a control device coupled to adjust the variable resistor. The control device is structured and arranged to set the resistance of the variable resistor to maximize noise filtering and optimize performance of the analog circuit.

Abstract: An analog finite impulse response (AFIR) filter including at least one variable transconductance block having an input for receiving an input voltage and being adapted to sequentially apply each of a plurality of transconductance levels to the input voltage during at least one of a plurality of successive time periods to generate an output current at an output of the variable transconductance block, the at least one variable transconductance block including a plurality of fixed transconductance blocks each receiving the input voltage and capable of being independently activated to supply the output current; and a capacitor coupled to the output of the variable transconductance block to receive the output current and provide an output voltage of the filter.

Abstract: This variable gain amplifier is provided with an operational amplifier. The non-inversion input terminal of the operational amplifier is connected to a reference potential. A feedback resistor is connected between the output terminal and inversion input terminal of the operational amplifier. An input resistor is inserted between the inversion input terminal of the operational amplifier and the input terminal of the variable gain amplifier circuit. An adjustment resistor is connected between the inversion input terminal of the operational amplifier and the reference potential. The resistance value of the adjustment resistor is controlled in such a way as to maintain constant against the resistance value change a combined resistance value in its parallel connection with the input resistor when changing the resistance value of the input resistor.

Abstract: An acquired signal indicative of electrophysiological activity is filtered using both a wavelet filter and either a notch filter or a band-pass filter to eliminate noise or interference, such as power line interference. A wavelet transform is used to transform the acquired signal into the wavelet domain, where a wavelet filter is applied to extract a soft component (e.g., a component with small wavelet coefficients). A filter, such as a notch filter or a band-pass filter, is applied to the soft component in order to isolate an interference signal. The interference signal is used to produce an output signal representing the acquired signal filtered to eliminate the interference signal. For example, the interference signal may be subtracted from the acquired signal. Alternatively, the output signal may be reconstructed from respective hard and soft components of the acquired signal as transformed into the wavelet domain.

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: Provided is a discrete filter capable of adjusting the number of notches and the notch frequency and easily eliminating a particular frequency component. In a sampling mixer (100), a control signal generation unit (104) generates a plurality of control signals having the same frequency and different phases. A convolution capacity unit (110) integrates the discrete signals obtained by sampling reception signals by using convolution capacitors at a timing based on the control signals. The signals integrated by the convolution capacitors are successively emitted at the timing based on a control signal other than the control signals used for the integration timing. Cb (15) integrates the emitted discrete signals.

Abstract: An integrated circuit includes a filter circuit that has at least one active device, wherein the active device has adjustable transconductance.

Abstract: A filtering module filters out high frequency signals, primarily noise, from an input data stream. The filtering module includes an input module, a phase detecting module, and a threshold module. The input module performs either a charging or a discharging across a capacitor on a basis of an RC time constant. The phase detecting module is coupled to the input module to keep identical phase at a first node and an output node. The threshold module is coupled to the phase detecting module for providing an output signal based on a threshold voltage and the charging or the discharging across the capacitor.

Abstract: A calibration circuit calibrates an adjustable capacitance of a circuit having a time constant depending on the adjustable capacitance. The calibration circuit outputs a calibration signal carrying information for calibrating the capacitor and includes a calibration loop.

Abstract: A bandwidth-adjustable filter includes an operational amplifier, a first resistor, a first capacitor and a first resistor ladder circuit. The operational amplifier has a negative input terminal and a positive input terminal. The first resistor is coupled to one of the input terminals of the operational amplifier. The first capacitor is coupled to the first resistor. The first resistor ladder circuit is coupled in parallel to the first resistor for changing the resistance of the first resistor so as to adjust the bandwidth of the filter.

Abstract: A circuit arrangement with an interference protection is disclosed, including a supply line and a ground line, a first circuit and a second circuit. Each of the first and second circuit is connected to the supply line and to the ground line. The circuit arrangement also includes a blocking device coupled to at least the supply line to suppress any interfering signals from being applied to the supply line.

Abstract: Switches with passive bootstrap that can achieve good sampling performance are described. In one design, a sampling circuit with passive bootstrap includes first and second filters and a switch. The first filter filters an input signal and provides a filtered input signal. The second filter filters a clock signal and provides a filtered clock signal. The switch receives a control signal formed based on the filtered input signal and the filtered clock signal and either passes or blocks the input signal based on the control signal. The first filter may be a lowpass filter having a first corner frequency that is higher than the bandwidth of the input signal. The second filter may be a highpass filter having a second corner frequency that is lower than the fundamental frequency of the clock signal. The first and second filters may both be implemented with one resistor and one capacitor.

Abstract: An object of the present invention is to provide a filter circuit which improves NF of a Gm-C filter. The filter circuit comprises a filter comprising at least one first operational transconductance amplifier whose mutual conductance varies depending on a first control signal and a first capacitor, a second operational transconductance amplifier whose mutual conductance is controlled by the first control signal, a third operational transconductance amplifier whose mutual conductance is controlled by a second control signal, and a second capacitor connected to output terminals of the first and second operational transconductance amplifiers and input terminals of the filter.

Abstract: A filter device is disclosed that includes a switched capacitor circuit.

Abstract: An active filter includes a first filter and a second filter. The first filter receives an input signal, and generates a first output signal by filtering the input signal. The second filter receives the first output signal during a time period adjusted based on a variation of a time constant of the first filter, and generates a second output signal by filtering the first output signal received during the time period. Therefore, a variation of a time constant is compensated by using post integration time control.

Abstract: Apparatus and methods tune analog filters that are parts of systems. When an analog filter is inserted into a system, the analog filter can be difficult to tune because of the difficulty in observing the analog filter's characteristics without being interfered by other circuits in the system. In one embodiment, analog filters are bypassed, and a response is determined. To this response, a time-invariant digital filter is applied to generate a reference response, such as an ideal response. The analog filters are then enabled and adjusted so that the difference between the response of the system and the reference response is minimized. This technique can be applied to arbitrary-order analog filters and can be used even when other circuits affect the observed filter response.

Abstract: Provided is a tuning circuit of a Gm (transconductance)-C (capacitance) filter. The tuning circuit tunes a transconductance using direct current incorporating variations of a capacitance, instead of a clock signal, in a Gm tuning mode, while using the clock signal in a capacitance tuning mode. As such, it is possible to prevent deterioration of a received signal caused by the clock signal.

Abstract: A filler circuit cell is disclosed. The filler circuit cell includes a decoupled capacitor, a tie low circuit and a tie high circuit. The decoupled capacitor includes a first NMOS transistor and a first PMOS transistor, in which the source/drain of the first NMOS transistor is connected to a second voltage source and the source/drain of the first PMOS transistor is connected to a first voltage source. The tie low circuit includes a second NMOS transistor and a second PMOS transistor and the tie high circuit includes a third NMOS transistor and a third PMOS transistor.

Abstract: A notch filter suitable for attenuating certain frequencies of a radio-frequency signal includes an input for receiving the radio-frequency signal and an output for the output of a portion of the radio-frequency signal, first and second capacitive means, at least one inductor and a negative resistance circuit suitable for compensating the resistive losses of said at least one inductor. The inductor and the first and second capacitive means are placed to produce a resonator and the filter comprises a control device suitable for controlling the negative resistance circuit. The input impedance of the filter comprises a pole and a zero, with the pole depending on the second capacitive means and the zero depending on both the first and second capacitive means. The first and second capacitive means are variable and the control device is suitable for controlling the first and second capacitive means.

Abstract: A filter circuit is disclosed which comprises a differential amplifier and a switch-capacitor circuit. The invention attains the goals of reducing the power consumption and the circuit size by sharing an amplifier with other related circuits to reduce the number of amplifiers.

Abstract: An active RC filter has an op-amp and a biasing circuit arranged to bias the op-amp to set a gain bandwidth product of the op-amp according to a desired pole frequency of the filter. The biasing circuit is operable according to an output of an RC calibration circuit. The op-amp can be an OTA transconductance amplifier, and the biasing circuit can be arranged to maintain a constant product of R and transconductance at an input of the transconductance amplifier. This biasing can help to set the pole frequency more accurately and can thus reduce the need for bandwidth margin to be provided to allow for manufacturing process variations.

Abstract: An active filter comprising a first stage (10), a second stage (20) and a third stage (30), each of them being provided with a respective operational amplifier (11, 21, 31); a feedback branch (50) defined by a resistor (51) connects the output (31c) of the third operational amplifier (31) to the inverting input (11a) of the first operational amplifier (11). A main resistor (60) is connected between the inverting input (11a) of the first operational amplifier (11) and a fixed-potential node, and in particular a grounded node.

Abstract: Low flicker noise mixer and buffer. This design employs some native metal oxide semiconductor field-effect transistors (MOSFETs) (e.g., having no threshold voltage) within a passive mixer whose gates are driven using clock signals. These native MOSFETs maybe biased at one half of the power supply voltage to provide a lower noise figure. A cooperatively operating buffer employs appropriately places MOSFETs and resistors to ensure the desired gain. Relatively larger valued resistors can be employed to provide for higher voltage gain, and this can sometimes be accompanied with using a higher than typical power supply voltage. Source followers serve as output buffers and also ensure the required output DC voltage level as well. It is also noted that this design can be implemented using n-channel metal oxide semiconductor field-effect transistors (N-MOSFETs) of p-channel metal oxide semiconductor field-effect transistors (P-MOSFETs).

Abstract: In one embodiment, a plurality of ESD devices are used to form an integrated semiconductor filter circuit. Additional diodes are formed in parallel with the ESD structures in order to increase the input capacitance.

Abstract: Embodiments of an active bandpass filter are described. Such a filter includes a transistor; a series-tuned inductive-capacitive (LC) network (STLCN) in a common source circuit associated with the transistor to produce a tuned degenerative filtering of at least one interfering signal; and a first, variable resistance associated with the STLCN to provide a first control of a resonance quality factor (Q) associated with the filter. Other embodiments may be described and claimed.

Abstract: An analog finite impulse response filter including at least one variable transconductance block having an input for receiving an input voltage and being adapted to sequentially apply each of a plurality of transconductance levels to the input voltage during at least one of a plurality of successive time periods to generate an output current at an output of the variable transconductance block, the at least one variable transconductance block including a plurality of fixed transconductance blocks each receiving the input voltage and capable of being independently activated to supply the output current; and a capacitor coupled to the output of the variable transconductance block to receive the output current and provide an output voltage of the filter.

Abstract: An equalizer includes at least two first mutually interfering equalizer sections, and at least two second interference-correcting equalizer sections, arranged in series. Each of the second equalizer sections corresponds with one first equalizer section, such that although each corresponding equalizer has the same center frequency, the second equalizer sections have an equalization response opposite the interference effect, and the gain of the corresponding second equalizer at the respective common center frequency contains the negative gain of at least one first equalizer adjacent to the corresponding first equalizer at the center frequency of the corresponding first equalizer.

Abstract: The present invention addresses a need for reducing the power consumption in a baseband filter used in a front-end wireless receiver while providing the necessary linearity. In particular, relatively high linearity can be obtained with lower power consumption than has heretofore been the case. This is achieved in embodiments of the invention using an optimized single-branch fully differential structure which operates as a “composite” source-follower (when using CMOS devices) with an ideal unitary dc gain. A positive feedback internal to the source follower allows one to synthesize two complex-poles.

Abstract: Provided is a noise filter circuit capable of outputting only a normal signal pulse in synchronization with a clock signal without passing the noise pulse on to a subsequent stage, even if a noise pulse having a width that is larger than a delay time is inputted. The noise filter circuit according to the present invention has a flip-flop additionally provided to a stage subsequent to a noise removing circuit that uses a delay circuit. The delay time of a clock signal inputted to the flip-flop is made different from the delay time of the noise removing circuit to thereby obtain a normal signal pulse to be outputted in synchronization with the clock signal.

Abstract: An integrated, multi-band radio frequency (RF) filter is capable of modifying a filter response thereof in response to control information. Switching elements within the filter can be changed between on and off conditions to modify the filter response. In one implementation, the integrated, multi-band filter is integrated on a front end module chip to be used within a multi-radio wireless device. In at least one embodiment, linearity enhancement circuitry is provided within a multi-band filter to improve linearity and reduce insertion loss.

Abstract: Loop filters are provided, in which a first resistor comprises a first terminal coupled to a first node, and a second terminal coupled to a second node; a first capacitor is coupled between the second node and a ground voltage, a second resistor comprises a first terminal coupled to the first node and a second terminal coupled to a third node. An operational amplifier comprises a non-inversion input terminal coupled to the second node, an inversion input terminal coupled to the third node, and an output terminal, and a second capacitor is coupled between the output terminal of the operational amplifier and the third node.

Abstract: Systems and method for tracking different types of transconductance cells is shown and described. In these multi-cell systems, the addition of one or more tracking control modules allows circuit designers to advantageously incorporate multiple transconductor topologies and their uniquely beneficial characteristics into their designs, without eradicating its centralized multi-cell tuning functionality.

Abstract: A discrete time analog filter suitable for use in a receiver and other electronics devices is described herein. In one exemplary design, an apparatus may include a transconductance amplifier, a sampler, and a discrete time analog filter. The transconductance amplifier may amplify a voltage input signal and provide an analog signal. The sampler may sample the analog signal and provide analog samples at a sampling rate. The discrete time analog filter may filter the analog samples and provide filtered analog samples either at the sampling rate for a non-decimating filter or at an output rate that is lower than the sampling rate for a decimating filter. The discrete time analog filter may also filter the analog samples with either equal weights for a rectangular filter or at least two different weights for a weighted filter.

Abstract: A method for reducing a disturbance in an output signal caused by a disturbing signal in a multiport connector, a multiport connector circuit and a mobile device are described.

Abstract: The invention discloses an electrical component with a carrier substrate, on which at least one semiconductor chip is mounted. Terminal areas are arranged on the underside of the carrier substrate and contact areas designed for the assembly with semiconductor chips are arranged on the upper side. The carrier substrate has a functional area that is divided into sections, wherein each section is assigned at least one function such as, e.g., as a filter, a frequency-separating filter, a balun, etc. A separate area of the carrier substrate is assigned to each section. The following applies to at least one of the sections: the contact area and/or the terminal area that is conductively connected to the section lies outside the base of this section. The connecting line that conductively connects the input or output of the respective section to the contact area and/or the terminal area is preferably shielded from the section by a ground area.

Abstract: The invention provides a system for providing tunable balanced loss compensation in an electronic filter. Tunable balanced loss compensation is provided by using cross-connected balanced transconductors and self-connected balanced transconductors. The cross-connected balanced transconductors and the self-connected transconductors compensate the unbalanced loss across the electronic filter. The self-connected balanced transconductors compensate the balanced loss across the electronic filter. Further, the cross-connected and the self-connected balanced transconductors are tunable by adjusting the values of their transconductances, thereby providing tunable balanced loss compensation.

Abstract: In an apparatus and method for reducing current leakage in a phase locked loop (PLL), a pair of resistive divider circuit is coupled to receive a pair of differential input signals and provide a pair of differential output signals. A timing control circuit controls a pair of switches, the pair of switches being operable to conduct the pair of differential output signals in response to at least one signal of the pair of differential input signals being present. An operational amplifier (OA) includes a pair of OA input terminals and an OA output terminal. The pair of OA input terminals is coupled to receive the pair of differential output signals conducted by the pair of switches. A feedback circuit is coupled between the OA output terminal and a first one of the pair of OA input terminals. The pair of switches is disabled by the timing control circuit to block a current leakage from the feedback circuit.

Abstract: An active EMC filter for machine tools allows reducing the leakage current normally induced by large phase-to-ground capacitances. The filter may comprise an active shunt module or an impedance converter or a correction signal generator and is suitable both for three-phase and single-phase applications.

Abstract: One embodiment of an apparatus for cancelling supply noise includes an input circuit operable to receive an input from a charge pump and a drive circuit connected to an output of the input circuit. The drive circuit is operable to provide an output matching the input to the input circuit when a voltage source powering the input circuit and the drive circuit is stable, and to introduce a contrary voltage change on the buffered output when the voltage source is noisy, with the contrary voltage change being contrary to a voltage change on the voltage source due to noise.

Abstract: A method for tuning a filter is provided. The method includes: enabling a VCO circuit, wherein at least a portion of the VCO circuit is selected from the filter; generating an oscillation signal by the VCO circuit according to a driving signal; comparing the oscillation signal with a reference signal and generating a comparison result; and adjusting the driving signal according to the comparison result.

Abstract: An adaptive equalizer including an equalizer filter and a tap coefficients generator used to process a sample data stream derived from a plurality of received signals is disclosed. The tap coefficients generator includes an equalizer tap update unit, a vector norm square estimator, an active taps mask generator, a switch and a pilot amplitude reference unit used to minimize the dynamic range of the equalizer filter. A dynamic mask vector is used to mask active taps generated by the equalizer tap update unit when an unmasked signal output by the equalizer filter is selected by the switch to generate an error signal fed to the equalizer tap update unit. A fixed mask vector is used to mask active taps generated by the equalizer tap update unit when a masked signal output by the equalizer filter is used to generate the error signal.

Abstract: An active electromagnetic interference (EMI) filtering may reduce the requirements for high current differential mode inductors. The active EMI filtering of the present invention may be useful in power devices that use switching power converters. Conventional EMI differential mode filtering devices may occupy up to 30% of the total weight and volume of the power electronics. Conventional differential mode filtering inductors tend to be large and heavy, especially so for high current input power lines. The present invention may replace the large conventional differential mode filtering inductors with a smaller set of coupled inductors.

Abstract: An active compensation filter for the application in the electric power supply in a land vehicle, which comprises a high-pass filter which is to be coupled with a supply voltage line which carries a supply voltage, in order to detect frequency and amplitude of interference voltage components of the supply voltage. A signal amplifier which is connected in series with the high-pass filter amplifies the detected interference voltage components and supplies them to a coupling element as output signals, which is connected in series with the signal amplifier and comprises a primary side and a secondary side. The primary side is fed with the output signals of the signal amplifier and the secondary side is looped into the supply voltage line.