Abstract: A radio-frequency ??-modulator comprises a first mixer in the forward path for down-converting the signals in this forward path with a local oscillator frequency and a second mixer in the feedback path for up-converting the feedback signal with the same local oscillator frequency. Delays between the two mixing operations cause a loss of gain in the loop of the ??-modulator. An adjustable amplifier in the feedback path compensates for this loss of gain.

Abstract: Receivers (1,11) for receiving radio frequency signals are provided with modulating stages (4,14) between mixing stages (3,13) and filtering stages (5,15) for deltasigma modulating intermediate frequency signals, to shape the quantisation noise out of the frequency band in which the wanted channel is located. Modulating stages (4,14) comprise delta-sigma modulators (41,42,43,90) with low-pass filters (91), quantisers (92) and digitalto-analog converters (93) having a low resolution and therefore a low power consumption. Due to delta-sigma modulating being done through a feedback loop, the receivers (1,11) have become less critical. The low-pass filters (91) comprise time-continuous filters, to avoid antialiasing filtering. The receivers further comprise digital further mixing stages (6, 16) coupled to the filtering stages (5, 15) for generating baseband signals and digital further filtering stages (7, 17) coupled to the further mixing stages (6, 16) for channel selective filtering the baseband signals.

Abstract: A pulse generator comprising a series coupling of delay elements (D1, D2, D3, D4, D5) every two consecutive delay elements (D1, D2, D3, D4, D5) being coupled at a plurality of coupling points (A1, A2, A3, A4), the series coupling of delay elements (D1, D2, D3, D4, D5) having a first end (A0) and a second end (A5) coupled to a first signal (y) and a second signal (x), respectively, the first and second signals (x, y) having a same frequency and being mutually phase-shifted, the pulse generator being characterized in that it further comprises a zero-crossing detector (3) coupled to two mutually different coupling points (A2, A3) for generating an output pulse (O) having a duration determined by a ratio between a number of delay elements between the two different coupling points and a total delay of the series coupling of delay elements.

Abstract: A tuning system (100) for receiving a radio frequency input signal included in a frequency range, the range having a maximum frequency and a minimum frequency and a plurality of non-overlapping bands, the tuning system (100) comprising a voltage-controlled oscillator (6) controlled by an analog signal (VT) and a first binary signal (D) and being characterized in that the analog signal (VT) is inputted to a window comparator (1), said comparator (1) having a low threshold (VL) which is indicative for the minimum frequency and a high threshold (VH) which is indicative for the maximum frequency.