Cambridge Silicon Radio Limited

Qualcomm Technologies International, Ltd.

David Chappaz

Andrei Popescu

James Digby Yarlet Collier

Diego Giancola

Farshid Nowshadi

Duncan Mcleod

The present application relates to a pulse-width modulation generator for generating a pulse-width modulated signal, the PWM generator comprising: a PWM modulator; and a loop filter, wherein the loop filter is configured to receive an input signal and to output a filtered signal to the PWM modulator, and the PWM modulator is configured to receive the filtered signal from the loop filter and to output a pulse-width modulated signal, the PWM generator further comprising: a feedback loop coupling an output of the PWM modulator to an input of the loop filter, wherein the feedback loop includes a comb filter.

Pulse-width modulation generator

Devices and methods convert signals into pulse-width modulated signals. A noise-shaping loop can be clocked at a lower frequency than a PWM modulator, resulting in lower power requirements, and greater ease of synchronization. The delay introduced by the noise-shaping loop can be reduced by implementations using sample-and-hold devices, look-up tables and logic circuitry to predict output signals.

Devices and methods for pulse-width modulation

A signal converter directly converts pulse-density-modulated (PDM) signals into pulse-width-modulated (PWM) signals. A noise-shaping loop architecture can be configured to apply a signal transfer function having a low-pass filter effect, and a noise transfer function having a high-pass filter effect. Decimation and interpolation can ensure that the noise-shaping loop architecture operates at a first sampling frequency, while the PWM modulator operates at a second, higher sampling frequency.

Devices and methods for converting digital signals

The present invention provides a locked loop circuit in which the input clock signal is delayed according to a saw-tooth signal in order to output a range of frequencies not necessarily equal to an integer multiple of the input clock signal. The absolute value of the delay (i.e. the difference between the maximum and minimum values of the saw-tooth delay) can be calibrated by detecting the value of the circuit phase detector at the wrap point of the saw-tooth.

Locked loop circuits and methods

Receiving a Wi-Fi radio signal using a Bluetooth receiver architecture. Also, adapting a Wi-Fi receiver architecture to constrain a received radio signal to less than the bandwidth of a conveyed Wi-Fi signal for subsequent processing purposes.

Schemes for the efficient reception of radio communications signals

A receiver () for a telecommunications system, the receiver () comprising a channel impulse response estimator () for producing an initial estimated channel impulse response of an overall multipath channel of the telecommunications system and a processing unit () for calculating, from the initial estimated channel impulse response, an estimate of the gain of each component of a propagation channel impulse response represented by the initial estimated channel impulse response.

Receiver

Embodiments of the invention provide a decoder arrangement (), wherein a decoder () which is adapted to decode a bitstream which has been encoded with a non-recursive convolutional encoder is used to at least partially perform the decoding of a recursive convolutionally encoded bitstream, with pre-or post-processing () of the bitstream being performed to complete the decoding. More particularly, in one embodiment of the invention a recursively encoded bitstream is input into a conventional decoder () which is adapted to decode a non-recursively encoded bitstream. The resulting intermediate output does not represent the correct decoded bitstream, but can then be subject to a post-processing step in the form of a non-recursive encoding operation (), which effectively completes the decoding operation and provides as its output the correct decoded bitstream. Both hard decision or soft decision inputs can be used.

Decoding of recursive convolutional codes by means of a decoder for non-recursive convolutional codes

The present invention provides a single modulator capable of transmitting an input according to a first and a second modulation technique. The first modulation technique represents changes in the input using a first set of carrier waveform parameters, such as phase variations, whereas the second modulation technique represents changes in the input using a second set of carrier waveform parameters, such as alternative phase variations. The present invention performs both modulation techniques by expressing the 10 second set of carrier waveform parameters as a subset of the first set of carrier waveform parameters. In a preferred embodiment, the first and second modulation techniques comprise the &#x3c0;/2-offset 2PSK (a good approximation of differential GMSK) and 3&#x3c0;/8-offset 8PSK (also known as EDGE) modulation techniques.

Dual purpose modulator

A method and apparatus for performing calculations relating to the derivation of log-likelihood ratio (LLR) is provided. Coefficients in the use of deriving LLRs are calculated the calculation being applicable to any one of a plurality of constellation diagrams (PAM, QAM, PSK). The coefficients may be stored in a table of coefficients, the table corresponding to a particular constellation diagram and modulation scheme. A number of tables may be stored, each table corresponding to a particular modulation scheme. The coefficients are related to a symbol estimated to be closest to the received sample and the closest symbol to the estimated symbol having a complementary value for a bit for which the LLR is to be calculated. Certain coefficients or parts of coefficients may be omitted where the corresponding constellation diagram has symmetries.

Method and apparatus for performing log-likelihood calculations

A method and apparatus for aligning I- and Q-signals in a quadrature receiver based on an squared signal. A correction is evaluated in an iterative manner by finding an average of the squared signal. The average squared signal may be the received signal, in which case the iterations are applied in a feed forward manner. Alternatively, the average squared signal is the aligned signal in which case the iterations are applied in a feed back manner. The correction may include the evaluation of an normalization or, in the feed back case, this can be implicitly included in the manner in which the iteration is applied. Various parameters to the iteration can be set to accommodate the operating environment of the receiver and characteristics of the received signal.

Adaptive IQ alignment apparatus

A device and method of combining a first version of an information block and a second version of the information block is disclosed. The method comprises calculating, prior to combining the first and second versions of the information block, a scaling factor to be applied in combining the first and second versions of the information block to produce a scaled combined information block.

Device and method of data combining

A receiver for a telecommunications system in which a data signal is transmitted using a closed loop transmit diversity system and a pilot signal is transmitted using a space time transmit diversity system, the receiver comprising an equalizer for equalising a signal received by the receiver, wherein the equalizer is configured to produce an equalized signal in which effects caused by a propagation channel through which the data signal was transmitted are alleviated, the receiver further comprising a processor for processing the equalized received signal to recover the pilot signal.

Two versions of the auto-covariance matrix of a received signal are obtained. One version is dependent upon the fraction of the power of a transmission site that goes into the wanted signals and a value is sought for this fraction that produces a good match between the two versions.

Signal power estimation

A method of estimating a symbol that has been transmitted into a channel connecting a modulator for producing modulation symbols and an equaliser, wherein a channel estimate describes said channel and the method comprises: calculating a metric for each of a number of hypotheses of a sequence commencing with the symbol under estimation followed by a number of subsequently transmitted symbols, each symbol in the sequence occupying a respective node of the sequence; and deeming the symbol at the beginning of the hypothesis that has the best metric to be the symbol under estimation; wherein calculating a metric for a given hypothesis comprises: calculating a discrepancy metric at each node of the given hypothesis; and combining the discrepancy metrics of nodes in the given hypothesis to produce the metric; and wherein a discrepancy metric for a given node of a given hypothesis is an assessment of the difference between: a sample received from said channel at a time point corresponding to said given node; and a sample that would be received at that time point if said channel estimate were acting on a model signal comprising the symbols of the given hypothesis up to the given node preceded by any estimates of symbols transmitted into the channel immediately prior to said time point as may be required to fill the estimated channel. The invention also relates to corresponding apparatus.

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Milton, United Kingdom

David Chappaz