Abstract: A method for tuning a filter is provided. The amplitude of a first signal (I1) is compared with the amplitude of a comparison signal. The first signal is generated with a first filter, which receives a first input signal, and there is a phase difference between the first signal (I1) and the comparison signal. A tuning signal is then generated based on differences between the amplitudes of the first signal (I1) and the comparison signal. The tuning signal compensates for any phase and/or amplitude offset in the first signal (I1).

Abstract: A transceiver device that performs an intercept point calibration using signal interferers is described. The signal interferers include at least self-generated signal interferers or opportunistic signal interferers in surrounding areas. Due to non-linearity in the transceiver device, intermodulation distortion (IMD) signal components are generated. Filtering of the IMD signal components is performed to allow low-frequency components, such as a second order intermodulation (IM2) to pass through. A dynamic minimization algorithm is performed to minimize distortion effects of the low-frequency components.

Abstract: Exemplary embodiments of the invention disclose signal filtering. In an exemplary embodiment, a filter device may comprise a subtractor operably coupled between an input and an output and configured to receive an input signal comprising a desired component and at least one undesired frequency component. The filter device may further include a feedback loop configured to receive at least one of the input signal and an output signal from the subtractor and convey a feedback signal comprising at least one undesired component to the subtractor. Each undesired component of the feedback signal corresponds to an associated undesired component of the input signal. Furthermore, the subtractor subtracts the feedback signal from the input signal and convey the output signal.

Abstract: To provide a charge sampling filter circuit and a charge sampling method. A charge sampling filter circuit includes a first capacitor that samples an input signal, and in which at least a portion of electric charge stored in the first capacitor by sampling is output to a second capacitor that is connectable with the first capacitor. The charge sampling filter circuit is characterized by including a switching portion that switches a circuit mode including a sampling mode that causes the first capacitor to sample the input signal, and an output mode that causes the first capacitor and the second capacitor to be connected. A capacitance value of the first capacitor in the output mode is set to be lower than the capacitance value in the sampling mode.

Abstract: A signal processing arrangement (REC) comprises a filter (PPF) with variable filter elements (FE). A switching circuit (SWCT) switches a filter element (FE1) and, subsequently, another filter element (FE3) from a filter state to an adjustment state and back again to the filter state. A filter element that is in the filter state contributes to a suppression of unwanted signals. A filter element that is in the adjustment state affects a characteristic of a measurement signal (Sm). An adjustment circuit (ADCT) adjusts the filter element that is in the adjustment state so that the characteristic of the measurement signal is substantially equal to a target value (TV).

Abstract: An embodiment of a baseband filter in a transmitter subsystem of a wireless device comprises an operational amplifier (op-amp), a pole circuit, a feedback capacitor, and an active device. The op-amp is adapted to produce an amplified signal that includes noise gain produced by the op-amp. The pole circuit is electrically coupled with an output terminal of the op-amp, and is adapted to receive the amplified signal and to attenuate the noise gain to produce a filtered, amplified signal. The feedback capacitor is electrically coupled between the first pole circuit and an input terminal of the op-amp, and is adapted to compensate for a phase shift produced by the pole circuit. The active device is electrically coupled with the pole circuit, and is adapted to amplify the filtered, amplified signal and to produce a baseband filtered output signal.

Abstract: The present invention relates to a communication system and methods of use thereof. The system includes sets of complementary radios for transmitting and receiving signals to achieve high reliability and reduced costs. The sets of complementary radios are in wireless communication with each other. A new connection is made by selecting from amongst the complementary radios. Switching between complementary radios during a connection is also permitted. Optimized protocols and hardware for implementing the system are disclosed.

Abstract: Provided are a terminal and a base station, and a frequency sensing method thereof. The terminal or the base station may filter a frequency band needing frequency sensing in the entire frequency band where the terminal or the base station may receive an input signal. It is possible to enhance a detection performance and rate of signals by applying frequency sensing to the filtered frequency band.

Abstract: A circuit for communicating information in a wireless network includes a filtering circuit in communication with a zero intermediate frequency (ZIF) transceiver circuit. The filtering circuit includes a first mixer in communication with an output of the ZIF transceiver circuit. The filtering circuit includes a first Surface Acoustic Wave (SAW) filter circuit in communication with an output of the first mixer. The filtering circuit includes a second mixer in communication with an output of the first SAW filter circuit. The filtering circuit includes a third mixer, and a second SAW filter circuit in communication with an output of the third mixer. The filtering circuit includes a fourth mixer in communication with an output of the second SAW filter circuit and an input of the ZIF transceiver circuit. The filtering circuit also includes a local oscillator circuit in communication with the first, second, third and fourth mixers.

Abstract: A radio transceiver device includes circuitry for radiating electromagnetic signals at a very high radio frequency both through space, as well as through wave guides that are formed within a substrate material. In one embodiment, the substrate comprises a dielectric substrate formed within a board, for example, a printed circuit board. In another embodiment of the invention, the wave guide is formed within a die of an integrated circuit radio transceiver. A plurality of transceivers with different functionality is defined. Substrate transceivers are operable to transmit through the wave guides, while local transceivers are operable to produce very short range wireless transmissions through space. A third and final transceiver is a typical wireless transceiver for communication with remote (non-local to the device) transceivers.

Abstract: A radio frequency (RF) transmitter includes a transmitter processing module that generates a processed signal based on outbound data, wherein the processed signal includes one of: a baseband signal and a low intermediate frequency signal. An up-conversion module up-converts the processed signal to generate an up-converted signal. A programmable filter module generates a plurality of delayed signals from the up-converted signal and that generates a filtered up-converted signal by combining the up-converted signal and the plurality of delayed signals, wherein a delayed signal of the plurality of delayed signals is scaled based on one of a plurality of coefficients, wherein the plurality of coefficients are selected based on a control signal. A radio transmitter front-end generates a transmit signal based on the filtered up-converted signal. A processing module generates the control signal to attenuate at least RF spur of the up-converted signal.

Abstract: A radio receiver comprising: a frequency shifter for receiving a radio frequency signal including a wanted signal in a first frequency band and an interferer in a second frequency band overlapping the first frequency band, and for frequency shifting the radio frequency signal to form a frequency shifted signal, in which the first frequency band is shifted to a third frequency band below radio frequency and the second frequency band is shifted to a fourth frequency band; and a filter for receiving the frequency shifted signal and for attenuating the fourth frequency band relative to the parts of the third frequency band that do not include the fourth frequency band, wherein the filter is dynamically tuneable.

Abstract: The present invention offers significant improvements in the performance of a radio receiver operating in an environment with high desired band interference. The present invention comprises a high selectivity RF circuit that is located between the antenna and the radio receiver, and utilizes superheterodyne technology to filter adjacent channel interference in the desired band frequency spectrum. This type of interference is problematic for IEEE 802.11 radio receivers that are implemented with the popular direct conversion radio receiver architectures. The present invention may be utilized in many types of radio receivers. The high selectivity RF circuit comprises channel select filters, a down-converter, an up-converter and a programmable local oscillator.

Abstract: A transceiver apparatus comprising a software-definable-radio-transceiver architecture. The transceiver apparatus comprises at least one up-conversion path including at least one configurable micro-electro-mechanical-system (MEMS) transmit filter communicatively coupled to transmit output from a digital-to-analog converter to an antenna, and at least one down-conversion path including at least one configurable-MEMS-receive filter communicatively coupled to transmit signals received from the antenna to an analog-to-digital converter. The at least one configurable-MEMS-transmit filter prevents interference on the up-conversion path from signals transmitted from the antenna. The at least one configurable-MEMS-receive filter prevents interference on the down-conversion path from signals transmitted to the antenna. A plurality of upconversion and downconversion paths can operate simultaneously and on different channel frequencies.

Abstract: An apparatus and method for processing a digital broadcast signal are provided. The method includes cutting off a noise frequency of a received digital broadcast signal and low-noise amplifying the noise cut-off signal, limiting an amplitude of the low-noise amplified signal spectrum to an amplitude of the digital broadcast signal spectrum, and cutting off a noise frequency of the amplitude limited signal spectrum and passing only a signal corresponding to a frequency band of the digital broadcast signal.

Abstract: A digital tuning system (250) for changing a cutoff frequency of an analog filter (132) includes digital synthesizers (292 and 294) for producing a two-tone calibration signal (196) applied to an input of the filter after a quality factor of the filter is increased. The filter includes at least one R/C circuit with two resistors (304 and 306) for changing the quality factor and arrays (308 and 310) of capacitors for changing the cutoff frequency. The amplitude of the magnitude responses (409 and 411) of the filter to each tone (405 and 407) is measured by a two discrete Fourier transform single-frequency bin power detection circuits (253 and 254) while the filter is sequenced through a plurality of capacitance settings. An optimal capacitance for the R/C circuit is selected by comparing, to a pre-selected value, a difference between the responses of the filter to each tone, for each capacitance setting.

Abstract: A system and method for implementing dynamic spur avoidance in a high speed receiver environment is provided. For a plurality of radio frequency (RF) input signal ranges, a range of intermediate frequency (IF) signals and a noise floor for each IF signal is determined. An identification of spurs that will affect the noise floor is also determined from a look up table for each range of the RF inputs. A frequency plan that sets local oscillator and constituent oscillator signals is selected such that the IF signals generated from the RF input will avoid lower order spurious responses of the identified spurs within the IF signal range.

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 signal is provided to each of nominal, higher and lower primary filters in a receiver. The nominal, higher and lower primary filters have different center frequencies and a bandwidth B1 and bandwidths B2, respectively and a bandwidth offset B0, with B2=B1+B0. Signal recovery is performed on the output of each primary filter to obtain recovered signals and error values each associated with one of the primary filters. Each error value is provided to a secondary and tertiary filter, to generate a signal criterion, and whose output is measured to generate a quality metric, respectively, associated with each recovered signal. The recovered signal associated with the nominal primary filter and any other recovered signal having an associated signal criterion below a threshold value is selected and the selected recovered signal which has the lowest associated quality metric is chosen.

Abstract: The invention relates to a filter device (341, 342) for detecting and/or removing erroneous components like noise, deformations, glitch components or other errors in and/or from a signal, to a demodulation device using the filter device, to an information transmission system using the demodulation device and to a method for detecting a noise impulse in an input signal (C?(t), C?[k]). The filter device includes a summing element (510-51N, 610) connected to a correction element (540, 640). The summing element (510-51N, 610) sums the input signal (C?(t), C?[k]) within a reference interval (N) and the correction element (540, 640) verifies the summed input signal (IS[k]) with at least one signal condition (0, N+1, ?C?[k]). Finally, the correction element (540, 640) outputs a predetermined signal (C??[k]) based on the result of the verification between the summed input signal (IS[k]) with at least one signal condition (0, N+1, ?C?[k]). The foregoing filter device is able to remove noise from an input signal.

Abstract: A receiver apparatus includes a band-pass filter having a variable frequency band coupled to a node for receiving a received signal including a plurality of channels to output at an output node thereof a limited-band signal made by limiting a frequency band of the received signal to a frequency band of a desired channel, a frequency conversion unit coupled to the output node of the band-pass filter to output at an output node thereof an intermediate frequency signal made by converting frequencies of the limited-band signal, and a control unit configured to adjust an intermediate frequency of the intermediate frequency signal by controlling the frequency conversion unit in response to at least one of a signal speed and a channel frequency interval of the received signal.

Abstract: An electronic device includes an antenna, a radio frequency circuit, and an impedance matching circuit that is connected between the antenna and the radio frequency circuit. The impedance matching circuit includes a plurality of impedance matching networks that are respectively associated with frequency bands used by the radio frequency circuit.

Abstract: An interference cancellation device comprises an input for a disturbed signal, a first frequency shifter, a bandpass filter, and a signal combiner. The first frequency shifter shifts the disturbed signal from an original frequency range to a filtering frequency range. The frequency-shifted signal is filtered by the bandpass filter. The filtered signal is supplied to the signal combiner which combines the filtered signal with the disturbed signal to substantially reduce the interference signal that is present in the disturbed signal. A method for interference signal cancellation is also proposed. Furthermore, a computer program product with instructions for the manufacture and a computer program product enabling a processor to carry out the method for interference signal cancellation are also proposed.

Abstract: An interference cancellation (IC) system and method for use within a 1553 communication system comprising a data bus carrying primary signals having a 1553 component and a non-1553 component are provided. The IC system has an input port, a 1553 data extraction block and an interference cancellation circuit with an interference measurement and a cancellation block. The interference measurement block receives 1553 decoded data from the 1553 data extraction block and a sampled primary signal via the input port, and, within an impulse response block, produces an interference signal based on a 1553 impulse response system model. The cancellation block subtracts the interference signal from the sampled primary signal and produces an output signal with the 1553 component substantially cancelled. Furthermore, an IC system using adaptive filtering techniques within the impulse response block is provided. The Least Mean Squares (LMS) algorithm can be used as an adaptive filter technique.

Abstract: Methods, systems, and apparatuses for filtering received radio frequency signals are provided. A first RF communication signal is received that includes a desired information signal portion and an undesired blocker signal portion that is offset in frequency from the desired portion. The first RF communication signal is amplified in a first signal path and is filtered in a second signal path. The filtering of the first RF communication signal in the second signal path includes: down-converting the first RF communication signal to a down-converted signal, high pass filtering the down-converted signal, and up-converting the high pass filtered down-converted signal to a second RF communication signal. The filtering of the first RF communication signal filters out the desired information signal portion from the second signal path. A signal phase is adjusted in the second signal path to match phase shifts between the first and second signal paths.

Abstract: An RF squarer circuit comprises a first RF multiplier and a first variable gain transimpedance amplifier (TIA). The first RF multiplier receives an RF input signal RFIN and provides a first output current. The first TIA receives the first output current as an input. The first TIA provides an output voltage VOUT.

Abstract: A multi-tap direct sub-sampling mixing system for wireless receivers is provided with a dynamically configurable passive switched capacitor filter. A front end amplifier is connected to receive a signal. The passive switched capacitor filter is connected to receive the amplified signal and has an output for providing a filtered signal. The switched capacitor filter has at least two sections that are each operable as a pole, wherein a first section of the at least two sections has sets of at least two stacked capacitors interconnected with a set of switches operable to amplify in input voltage provided to an input of the first section in response to operation of the set of switches; and a back end section connected to the output of the switched capacitor filter to receive the filtered signal.

Abstract: Disclosed is an apparatus in a diversity system of a mobile terminal having a main receiving unit and a sub-receiving unit, which includes a sub-antenna for receiving an input signal and a part of a transmitted signal of a transmitting unit, a band-pass filter (BPF) designed to greatly attenuate a low-band frequency of the part of the transmitted signal received through the sub-antenna, a high-pass filter (HPF) for additionally attenuating the part of the transmitted signal attenuated through the BPF, a low-noise amplifier for minimizing a noise of an output value of the HPF, an HPF for passing therethrough only a high-frequency component of an output value of the low-noise amplifier, and a mixer for mixing output values of the HPF and outputting a baseband signal. One of two BPFs in the sub-receiving unit is replaced by one HPF, and thus the HPF can be fabricated on chip with the terminal receiving unit.

Abstract: A quadrature modulator divides a part of a transmitted signal to generate a cancel signal. A signal comparator compares the amplitude and phase of the cancel signal which is generated by the quadrature modulator with those of a received signal, and outputs signals corresponding to the comparison results to the quadrature modulator. The quadrature modulator generates the cancel signal on the basis of the output signals of the signal comparator, and these components perform feedback control such that the cancel signal has the same amplitude as the leakage signal and is in phase with the leakage signal. A combiner combines the cancel signal with an antiphase cancel signal, which is made to be in opposite phase with the cancel signal outputted from the quadrature modulator, to cancel out the leakage signal.

Abstract: A radio receiver front-end includes first and second RF receiver sections and an RF combining module. The first RF receiver section is coupled to receive an inbound RF signal and provide to a first representation of the inbound RF signal, wherein the inbound RF signal includes a desired signal component and an undesired signal component. The second RF receiver section is coupled to receive the inbound RF signal and to provide a second representation of the inbound RF signal. The RF combining module is coupled to combine the first and second representations of the inbound RF signal to produce a desired RF signal, wherein the desired RF signal includes the desired signal component and an attenuated representation of the undesired signal component.

Abstract: A receiver architecture for canceling blocking signals in the receive path includes a low noise amplifier for receiving and amplifying an inbound RF signal to produce an amplified inbound signal, in which the inbound RF signal includes a modulated RF signal and a blocking signal, and a cancellation module for substantially canceling the blocking signal from the amplified inbound RF signal and substantially passing the modulated RF signal. The cancellation module cancels the blocking signal by generating an injection signal representative of the blocking signal, combining the blocking signal with the injection signal to produce an error signal, updating the injection signal based on the error signal and using the injection signal to cancel the blocking signal from the amplified inbound RF signal.

Abstract: A method and apparatus for recovering at least one signal of interest are provided. The method includes receiving an overall signal, the overall signal including the at least one signal of interest and a plurality of other signals, identifying at least one of the strongest components of the plurality of other signals, attenuating, using at least one MEMS resonator, any of the components identified by the identifying, wherein the overall signal will be modified to include the at least one signal of interest, attenuated versions of the components identified by the identifying, and the remaining portions of the plurality of other signals that were not subject to the attenuating, and recovering, after the attenuating, the at least one signal of interest.

Abstract: A filter circuit arrangement for filtering of a radio-frequency signal has a first tunable filter and a phase regulation loop in order to hold the first tunable filter to a transmission phase constant relative to the frequency of the radio-frequency signal. The filter circuit arrangement has a second tunable filter arranged parallel to the first tunable filter in the phase regulation loop. The first tunable filter and the second tunable filter exhibit different attenuation characteristics and are fashioned and connected within the phase regulation loop so that: a capture range of the filter circuit arrangement, in which a tuning of the phase regulation loop to a radio-frequency signal to be filtered is possible is dominated by the attenuation characteristic of the second tunable filter, and so that the transmission behavior of the filter circuit arrangement in operation is dominated by the attenuation characteristic of the first tunable filter, given a tuned phase regulation loop.

Abstract: A wireless communication apparatus includes a mechanism for estimating carrier-to-interference (C/I) ratio using a variable bandwidth filter. More particularly, the wireless communication apparatus includes a channel equalization unit coupled to a C/I ratio estimation unit. The channel equalization unit may be configured to calculate instantaneous carrier-to-interference (C/I) ratio values of a received signal. In addition, the C/I ratio estimation unit may be configured to calculate a C/I ratio estimate by filtering successive ones of the instantaneous C/I ratio values. The C/I ratio estimation unit may also be configured to determine whether a transmitter of the signal is transmitting voice data in a voice channel of the signal. The C/I ratio estimation unit may be further configured to inhibit the filtering in response to determining the transmitter of the signal is not transmitting the voice data such as during DTX mode, for example.

Abstract: Various embodiments are disclosed relating to Q-enhancement cells. According to an example embodiment, a circuit may include an inductor with a quality factor (Q), and a Q-enhancement cell coupled to the inductor. The Q-enhancement cell may include a current source having a variable bias current slope. Stability may, for example, be improved by providing a variable or programmable bias current slope for the Q-enhancement cell. In another example embodiment, a Q-enhancement cell may be used to compensate for Q degradation due to one or more switched capacitors in a circuit. The switched capacitors may be used, for example, for channel or frequency selection for the circuit. In another example embodiment, a Q-enhancement cell may be used to compensate for Q degradation caused by a transmission line.

Abstract: A system includes a filter and a tuner formed on an integrated circuit. The filter receives an input signal comprising a first number of channels and communicates an intermediate output signal comprising a second number of channels less than the first number of channels. The tuner is coupled to the filter and receives the intermediate output signal and communicates an output signal comprising a third number of channels less than the second number of channels.

Abstract: A circuit for communicating information in a wireless network includes a filtering circuit in communication with a zero intermediate frequency (ZIF) transceiver circuit. The filtering circuit includes a first mixer in communication with an output of the ZIF transceiver circuit. The filtering circuit includes a first Surface Acoustic Wave (SAW) filter circuit in communication with an output of the first mixer. The filtering circuit includes a second mixer in communication with an output of the first SAW filter circuit. The filtering circuit includes a third mixer, and a second SAW filter circuit in communication with an output of the third mixer. The filtering circuit includes a fourth mixer in communication with an output of the second SAW filter circuit and an input of the ZIF transceiver circuit. The filtering circuit also includes a local oscillator circuit in communication with the first, second, third and fourth mixers.

Abstract: A method for improving channel estimation in a wireless communication system is disclosed. A wireless signal that includes a plurality of multipath components is received. N channel estimates are then obtained, where N is any positive integer greater than one. Each channel estimate of the N channel estimates corresponds to a different multipath component of the plurality of multipath components. The effects of interference between the plurality of multipath components on the N channel estimates is then reduced.

Abstract: One or more embodiments of the invention comprise a continuous-time equalizer (CTE) for reducing both pre-cursor and post-cursor intersymbol interference (ISI) from data received from a communication channel. One such equalizer comprises two independent stages that process the input signal in parallel. One stage subtracts a scaled version of the derivative of the input signal from a scaled version of the input signal to reduce pre-cursor ISI from the input signal. The other stage adds a scaled version of the derivative of the input signal to a scaled version of the input signal to reduce post-cursor ISI from the input signal. The outputs from the two stages are then multiplied to arrive at an output signal in which both pre- and post-cursor ISI is minimized. Because the scalars used in each of the stages are independent, each can be adjusted for greater manipulation of the ISI-reduced signal.

Abstract: A digital signal processor (DSP) comprises an input terminal configured to receive an input, an adaptive nonlinear phase filter coupled to the input terminal, the adaptive nonlinear phase filter having a time-varying phase response, and an adaptive nonlinear amplitude filter coupled to the input terminal, the adaptive nonlinear amplitude filter having a time-varying amplitude response. A method of processing a signal comprises receiving the signal, sending the signal to an adaptive nonlinear phase filter, the adaptive nonlinear phase filter having a time-varying phase response, and sending the signal to an adaptive nonlinear amplitude filter, the adaptive nonlinear amplitude filter having a time-varying amplitude response.

Abstract: A method of filtering and a RF filtering circuit comprising a LO adapted to generate in-phase and quadrature LO signals; a quadrature passive mixer operatively connected to the LO; a filtering impedance operatively connected to the quadrature passive mixer, wherein the voltage at an input node of the quadrature passive mixer comprises the voltage across the filtering impedance up-converted to a frequency of a LO signal received by the quadrature passive mixer. Preferably, the voltage across the filtering impedance comprises a frequency of an input signal of the quadrature passive mixer down-converted by a frequency of the in-phase and quadrature LO signals and filtered by the filtering impedance.

Abstract: Embodiments of a SAW-less RF receiver front-end that includes a frequency translated notch filter (FTNF) are presented. An FTNF includes a passive mixer and a baseband impedance. The baseband impedance includes capacitors that form a low-Q band-stop filter. The passive mixer is configured to translate the baseband impedance to a higher frequency. The translated baseband impedance forms a high-Q notch filter and is presented at the input of the FTNF. In an embodiment, the capacitors are implemented using MOS capacitors. In another embodiment, the capacitors are partially formed from MOS capacitors and fringe capacitors. The FTNF can be fully integrated in CMOS IC technology (or others, e.g., Bipolar, BiCMOS, and SiGe) and applied in wireless receiver systems including EDGE/GSM, Wideband Code Division Multiple Access (WCDMA), Bluetooth, and wireless LANs (e.g., IEEE 802.11).

Abstract: An apparatus and a method for equalizing a received signal to generate an equalized signal are disclosed. The apparatus includes a channel estimator for generating a channel estimation value according to a preamble symbol in the received signal and for generating a channel response value according to the channel estimation value, an interference power estimation circuit for generating an interference power estimate according to a hard decision value, the channel response value, and the received signal, and an equalization circuit for equalizing the received signal according to the channel response value and the adjusted interference power estimate to generate the equalized signal. The hard decision value corresponds to the equalized signal.

Abstract: A time constant automatic adjusting circuit comprises: a filter circuit varying a phase of an clock signal to be input so as to output the clock signal; a phase comparison circuit comparing a phase of an output signal of the filter circuit with the phase of the clock signal, and outputting a predetermined voltage when the phase of the output signal and the phase of the clock signal are the same; at least three comparators comparing the output voltage with a plurality of different voltages; an up-down counter counting a number of output bits of either one of the at least three different voltages in accordance with an output result of the comparators; and a control circuit varying the time constant of the filter circuit in accordance with the number of output bits counted by the up-down counter.

Abstract: A method for receiving satellite broadcasting includes: amplifying an inputted satellite broadcasting signal; converting the amplified signal to a baseband signal by mixing the amplified signal with a center frequency of a selected channel; and varying a channel bandwidth of the baseband signal.

Abstract: In one embodiment, a set of tracking filters to be coupled between an amplifier and a mixer is provided. The tracking filters may be differently configured depending on band of operation. For example, a first set of the filters can be configured to maintain a substantially constant Q value across their operating bandwidth while a second set of the filters can be configured to maintain a substantially constant bandwidth across their operating bandwidth.

Abstract: Provided is a poly-phase filter capable of removing an image frequency of a terrestrial digital multimedia broadcasting (T-DMB) receiver in a low intermediate frequency (IF) structure applied to a mobile communication terminal and a receiver having the poly-phase filter. The poly-phase filter includes: a calibration control block for generating first and second filter characteristic control signals which determine electrical characteristics of the filter in response to a control signal including instructions for changing the characteristics of the poly-phase filter and holding the changed values; and a poly-phase filter block for performing filtering on a plurality of input signals having different phases from each other in response to the first and second filter characteristic control signals. Accordingly, the poly-phase filter has advantages of having constant electrical characteristics regardless of changes in a manufacturing process and temperature and a high-performance image rejection function.

Abstract: An FM receiver that is suitable for reducing a transmission bandwidth WF of a bandpass filter to remove adjacent-channel interference, and increasing WF to prevent audio distortion. A detection output signal SOUT is inputted to an HPF 122 when a reception electric field strength signal SM-DC indicates an intermediate or stronger electric field. In a weak electric field, an AC component signal SM-AC, which is extracted from an intermediate signal SIF1 prior to detection and which has fewer high-pass noise components than SOUT, is inputted to the HPF 122. A control circuit 120 detects a case as an adjacent-channel interference state when a large amount of high-pass components passes through the HPF 122, and reduces WF of an IFBPF 70 in order to remove adjacent-channel interference. When a small amount of high-pass components is transmitted, WF is increased in order to minimize audio distortion.

Abstract: Techniques for self-calibrating filtering circuits with feedback are described herein.

Abstract: A preselect circuit maintains the dynamic range of a received RF input signal during bandpass filtering of the received RF input signal. The preselect circuit includes a Q-deficient passive bandpass filter for coupling to an antenna to receive a received RF input signal. The preselect circuit further includes a Q-enhancement circuit coupled to the Q-deficient passive bandpass filter, wherein the Q-enhancement circuit increases a Q-value of the Q-deficient passive bandpass filter by compensating for resistive inductive losses in the bandpass filter.