196results about "Transversal filters" patented technology

A sampling system arranged such that a modulated signal received by an antenna and input via a low noise amplifier and a band-pass filter is sampled at a sampling frequency higher than the signal band of the modulated signal by a first sample and hold circuit and is input to an analog decimation filter to remove a frequency component which may turn out to be aliasing noise. The output of the analog decimation filter is sampled with a sampling frequency lower than the sampling frequency of the first sample and hold circuit by a second sample and hold circuit and is digitized by an A / D converter to be demodulated by a demodulator. The sampling system which can convert the modulated signal into a low frequency without using the highly precision mixer circuit or a filter having sharp characteristics may be provided by constructing as described above.

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.

Methods, apparatuses, and systems are presented for performing adaptive equalization involving receiving a signal originating from a channel associated with inter-symbol interference, filtering the signal using a filter having a plurality of adjustable tap weights to produce a filtered signal, and adaptively updating each of the plurality of adjustable tap weights to a new value to reduce effects of inter-symbol interference, wherein each of the plurality of adjustable tap weights is adaptively updated to take into account a constraint relating to a measure of error in the filtered signal and a constraint relating to group delay associated with the filter. Each of the plurality of adjustable tap weights may be adaptively updated to drive group delay associated with the filter toward a target group delay.

The invention discloses a channel estimation method of corpuscle filtration in the radio transmission domain, which comprises the following steps: estimating least square of channel according to known pilot information; getting initial value which is estimated by the pilot channel; installing particle range and particle amount; giving out initial weight of every particle; using likelihood function to calculate likelihood function value of weight value of every particle according to signal which is received by pick-up antenna; normalizating likelihood function value of every particle; getting normalizated weight value of every particle; using Bayes's theory to get probability distribution function value of current channel value; resampling particle according to judgement condition; transforming current particle to next pilot area; getting channel estimated value of all pilot areas; carrying out interpolation algorism; getting channel estimated value of all transmitted data symbol; finishing channel information estimation. The invention has moderate property and strong anti-noise ability.

A discrete time bandpass filter element (103) having multiple stages (201, 202, 203, 204, 205) for use in a time division duplex radio protocol communications system including an automatic gain control. Discrete time bandpass filter is used to generate delay and can replace SAW filters in a wireless frequency translating repeater.

A filter intended to receive a discrete time signal at a sampling clock frequency, comprising a determined number, greater than 2, of filtering units, each filtering unit comprising head capacitors in a number equal to the determined number, assembled in parallel between an input terminal and the terminal of an integration capacitor; and means for connecting, in successive clock cycles in a number equal to the determined number, successively each head capacitor to the input terminal, and for then simultaneously connecting the head capacitors to the integration capacitor, and in which the successive clock cycles during which the head capacitors of a filtering unit are connected to the input terminal are offset by one clock cycle from one filtering unit to the next one.

The invention describes a number of differential, balanced high-speed circuits that permit the design of a receiver with Electronic Dispersion Compensation (EDC) on a single semiconductor substrate, including the functions of an analog Fast Forward Equalizer (FFE), a Clock and Data Recovery, a Decision Feedback Equalizer (DFE), enhanced by additional circuits that permit control of the slicing level to compensate for pulse distortion, and control of the phase offset to set the optimal eye sampling time when a distorted signal is received. To provide the utmost speed of operation, all circuits including the phase locked loop, operate as differential circuits which include a number of improvements in the design of the charge pump, the decision feedback equalizer, the slicing level control, and others.

A first periodic voltage waveform (20) is downconverted into a second periodic voltage waveform (35, 36). A plurality of temporally distinct samples (SA1, SA2, . . . ) respectively indicative of areas under corresponding half-cycles of the first voltage waveform are obtained. The samples are combined to produce the second voltage waveform, and are also manipulated to implement a filtering operation such that the second voltage waveform represents a downconverted, filtered version of the first voltage waveform.

A digital / analog conversion apparatus for converting a digital signal into an analog signal. The digital / analog conversion apparatus can generate a high-quality analog signal, even when elements configuring the digital / analog conversion apparatus have variance, with high resolution and a small circuit size. The data conversion apparatus is provided with a first data converter for reducing the number of bits of an input signal, a second data converter for converting the format of the first output signal, and a third data converter for conversion into a code which corresponds to the history of the output from the second data converter.

An electronic filter operates as a correlator that provides a discrete approximation of an analog signal. The analog to digital conversion is integrated directly approximation calculation. An array of sample and hold circuits or single bit comparators provide outputs to a series of multipliers, the other input of which is a coefficient value of a Fourier series approximation of the desired frequency response. Each of the sample and hold circuits samples sequentially in time and holds its sample until the next cycle. Thus the sample point rotates in time through the array and each new sample is multiplied by a different coefficient. The output of the multipliers is summed for evaluation.

A charge domain filter circuit includes a first signal output portion, at least one second signal output, portion, a third signal output portion, and an adder portion. The first signal output portion outputs a first signal that is sampled at a specified time interval. Each second signal, output portion outputs a second signal that is sampled after a specified delay after the first signal is sampled. Where a plurality of the second signal output portions is included, the second signals are sampled in succession. The third signal output portion outputs a third signal that is sampled after a specified delay after the last second signal is sampled. The adder portion adds the first, second, and third signals together and outputs the result. The capacitance ratio of the sampling capacitors in the first signal output portion and the second signal output portion is one of continuously or discretely varied.

A charge domain filter device includes a SINC filter with a frequency characteristic expressed by a SINC function, and a bandpass filter connected to an output end of the SINC filter and having a frequency characteristic with a particular center frequency.

An analog finite impulse response (“FIR”) filter generates a continuous time output using a chain of tunable delay elements. The tunable delay elements generate a time delay in an input signal. A calibration circuit, consisting of a control loop, tunes the delay elements to provide precision in the time delay response of the delay elements. The control loop generates a delay adjustment, based on the period of reference signals, and the phase adjustment is used to tune the parameters of the delay elements. The tunable delay elements may comprise any combination of transmission lines, lumped elements and semi-lumped elements.

A distributed amplifier uses non-uniform filtering structures to provide better control over pass-band and stop-band characteristics. The various sections can have different tap coefficients. A notch filter can be implemented for interference suppression or pulse shaping in an ultra-wideband transceiver.

A charge domain filter device includes a SINC filter with a frequency characteristic expressed by a SINC function, and a bandpass filter connected to an output end of the SINC filter and having a frequency characteristic with a particular center frequency.