Methods and apparatus are provided for decimated interpolated clock/data recovery (ICDR) to perform asynchronous sampling of a received signal. A received signal is converted to a plurality of digital samples at a downsampled rate that is lower than a rate of the received signal. The plurality of digital samples are interpolated using a plurality of parallel interpolation filters operating at the downsampled rate. An output of each parallel interpolation filter is applied to a corresponding data detector operating at the downsampled rate to generate digital data. An estimate of a timing error is generated based on the digital data. The timing error values are processed to generate an interpolation phase value that is applied to the parallel interpolation filters. A recovered clock is optionally generated, having edges corresponding to a desired synchronous sampling period.

Methods and apparatus for asynchronous sampling of a received signal at a downsampled rate

A method of compensating for nonlinear distortions in a digital signal comprises receiving the digital signal, generating a nominal phase shifted signal based on the digital signal, generating a modeled distortion signal based on the digital signal and the nominal phase shifted signal, subtracting the modeled distortion signal from the digital signal, and generating a compensated signal. A compensating system comprises an input interface configured to receive a digital signal having nonlinear distortion, and a distortion model coupled to the interface, configured to generate a nominal phase shifted signal based on the digital signal, generate a modeled distortion signal based on the digital signal and the nominal phase shifted signal, subtract the modeled distortion signal from the digital signal, and generate a compensated signal.

Digital linearizing system

A digital channelizer employs a polyphase filter element in which a shift register is used to commutate time series data to a bank of polyphase filters at the inputs of an FFT module. The filter bank and FFT module are updated at a frequency that is independent of the rate that the data is fed into the buffer and filter/FFT cycle rates of less than the ratio of the input data rate to the number of input channels may be accommodated by the shift register commutation. The output of the FFT module is interpolation filtered by inserting interpolated points between adjacent data points in the channelized output stream to increase the output frequency by an integral multiple of the update rate of the polyphase filter/FFT update rate. By determining an integer, q, such that (Ro/Ri)(2N−q) is a non-zero integer l, where Ro is a desired output data rate, Ri is an input data rate and 2N is the number of output channels (M<N), updating the filter/FFT at a rate of Ri/(2N−q), and interpolation filtering by inserting l−1 interpolated data between each successive pair of channelized data, a desired output data rate can be matched with an input data rate.

Digital channelizer with arbitrary output sampling frequency

A multi-protocol receiver system for receiving wireless communications. The system comprises programmable stages for controlling each steps of the demodulation of at least one broadband signal to provide the I and Q signals of at least one specific frequency narrow band for further processing. The receiver can be used in a software defined radio system.

Multi-protocol receiver

A system and method for low-cost performance and compliance testing of local oscillators and transmitters for wireless RF applications. A preferred embodiment comprises observing a digital signal from within an RF circuit, manipulating the signal with digital signal processing techniques, and determining if the RF circuit passes a test based upon results from the manipulating. Since the signal is clocked at a much lower frequency than an RF output of the RF circuit and the manipulation is performed digitally, testing can be performed at different stages of the production cycle and expensive test equipment can be eliminated.

Radio frequency built-in self test for quality monitoring of local oscillator and transmitter

A poly-phase filter and an apparatus which compensates for timing error and a method for implementing such compensation are provided. The poly-phase filter can compensate for the timing and phase error of an input signal which occur in a time period which is shorter than the sampling period by obtaining impulse responses of a mother filter having a pass band of (Fs/2n) where Fs is the sampling frequency and n is a positive number, re-sampling the obtained impulse responses using a plurality of clock signals having a phase difference of (2*π/n s), and selecting one filter among the filter set having group delays corresponding to the detected phase, and filtering the input signal using the poly-phase filter constituted by a series of filter sets adopting the re-sampled respective impulse responses as transmitting characteristics of the element filters.

Apparatus and method for compensating for timing and phase error using a poly-phase filter

A poly-phase filter and an apparatus which compensates for timing error and a method for implementing such compensation are provided. The poly-phase filter can compensate for the timing and phase error of an input signal which occur in a time period which is shorter than the sampling period by obtaining impulse responses of a mother filter having a pass band of (Fs/2n) where Fs is the sampling frequency and n is a positive number, re-sampling the obtained impulse responses using a plurality of clock signals having a phase difference of (2* pi /n s), and selecting one filter among the filter set having group delays corresponding to the detected phase, and filtering the input signal using the poly-phase filter constituted by a series of filter sets adopting the re-sampled respective impulse responses as transmitting characteristics of the element filters.

Poly-phase filter, apparatus for compensating for timing error using the same and method

A polyphase filter, an apparatus for compensating for phase and timing errors using the same and a method therefor are provided. The poly-phase filter can compensate for the timing and phase error of an input signal having a frequency lower than a sampling frequency by obtaining impulse responses of a mother filter having a pass band of (Fs/2n) where Fs is the sampling frequency and n is a positive number, re-sampling the obtained impulse responses using a plurality of clock signals having a phase difference of (2** small Greek pi */ns), and selecting one filter among the filter set having group delays corresponding to the detected phase and filtering the input signal using the polyphase filter constituted of a series of filter sets adopting the re-sampled respective impulse responses as transmitting characteristics of the respective element filters.

Ko Jung-Wan

Papers

Apparatus and method for compensating for timing and phase error using a poly-phase filter

Poly-phase filter, apparatus for compensating for timing error using the same and method

Polyphase filtering arrangements

Meerfase-filter, inrichting en werkwijze voor het compenseren van een tijdvaststelfout met gebruikmaking van het filter.