Abstract: In an AD converter a primary ?A-modulator digitizes the analog input signal. The quantization noise generated thereby is isolated in the analog domain and digitized in a secondary ?A-modulator. The quantization noise so digitized by the secondary ?A-modulator is subtracted from the quantization noise in the output of the primary ?A-modulator. Because the quantization noise generated by the primary ?A-modulator is subject to filtering (shaping) the quantization noise digitized in the secondary ?A-modulator should also be filtered. This is performed by similar filtering in the feedback path of the secondary ?A-modulator.

Abstract: A receiver is suitable for use in a wireless communications system, which is subject to interference from interfering signals having much narrower bandwidths than the wanted signal. In the receiver, an interfering signal is detected in the frequency domain and moreover, the cancellation also takes place in the frequency domain. Detection and cancellation in the frequency domain also provides a way of estimating the magnitude of the interfering signal, and hence also allows the wanted signal, at the frequency of the interfering signal, to be estimated.

Abstract: Pulses are detected in a communications receiver by programming each of a plurality of comparators (44a, 44b, . . . , 44n) with a sampling time point selected from a plurality of sampling time points (58, 60) and with a reference level selected from a plurality of reference levels (54, 56). The received signal is applied to each of the comparators such that each of the comparators produces a respective output signal based on a comparison between the received signal level and the selected reference level at the selected sampling time point. The combinations of sampling time points and reference levels can be selected based on knowledge about the expected arrival times of the pulses, and based on knowledge about the possible shapes of said pulses, with the result that the device can detect received pulses without requiring large amounts of hardware, in a device which has an acceptable power consumption. The communications system may be a signaling system, or a radar or positioning system.

Abstract: A receive beamformer, and ultrasound system incorporating such a receive beamformer, is constructed to implement multi-bit analog to digital conversion in such a way that the need for gain control in the channel architecture preceding the digital conversion circuitry is obviated. Accordingly, the beamformer and any ultrasound system incorporating it may realize a rigorous level of ADC performance at desirable output rates, and a lower cost. Preferably, the invention construction realizes a level of performance by which CW Doppler may be digitized in the same manner as very wide-band pulsed-wave signals.