Abstract: A base station in a radio communication system uses complex bandpass filters &OHgr;1, &OHgr;2, . . . , &OHgr;N and down-sampling to channelize a wideband signal containing many channels or channel groups.

Abstract: A complex switched capacitor filter is formed by selecting an analog baseband prototype filter with the desired filter characteristics. This prototype is converted into a corresponding real switched capacitor filter, and finally the real switched capacitor filter is converted into a complex switched capacitor filter by replacing each element of real filter by a frequency shifted complex counterpart.

Abstract: A base station in a radio communication system uses complex bandpass filters &OHgr;1, &OHgr;2, . . . ,&OHgr;N and down-sampling to channelize a wideband signal containing many channels or channel groups.

Abstract: D/A-conversion of a Gray coded digital input signal is performed according to an inventive recursive Gray code-to-analog conversion algorithm. According to the recursive algorithm, the Gray code bits of the digital input are successively applied in the recursions of the algorithm, one Gray code bit for each recursion, and the analog output signal is generated by recursively updating an intermediate signal. In each recursion, the intermediate signal is selectively inverted in dependence on the particular Gray code bit that is applied in the recursion. The selective inversion of the intermediate signal is an inherent property of the Gray code-to-analog algorithm, and it is a key factor to reduce the accumulation of errors in a D/A-conversion. In a D/A-converter architecture based on the algorithm, the accumulation of offset errors will be low. Furthermore, the fact that the signal inversion is digitally controlled enables high precision implementations, further improving the performance of the D/A-converter.

Abstract: A desired programmable complex analog bandpass filter is replaced by a "black box" that receives an analog continuous-time signal and delivers an analog continuous-time signal, just as the analog filter would, but internally realizes the programmability with a programmable discrete-time system. The transfer function of the "black box" is the same as the transfer function of the analog filter. The "black box" includes an anti-aliasing filter, an A/D-converter, a complex digital bandpass filter (16), a D/A-converter (18) and an anti-imaging filter (20).

Abstract: Pipeline A/D-conversion of an analog input signal is performed according to a new and inventive algorithm which generates a Gray coded digital output signal. A pipeline A/D-converter comprises a number of cascaded stages through which the analog input signal is propagated. Each stage generally generates an output bit of the digital output signal, and furthermore processes the pipeline signal. According to the inventive Gray coding algorithm, the output bit generated in a stage determines whether or not the pipeline signal of that stage is inverted. In a pipeline A/D-converter based on the Gray coding algorithm according to the invention, the accumulation of offset errors will generally be very low. Furthermore, the fact that the signal inversion is digitally controlled enables high precision implementations which further improve the performance of the inventive pipeline A/D-converter.

Abstract: Cyclic A/D-conversion of an analog input signal is performed according to a new and inventive recursive algorithm which generates a Gray coded digital output signal. In cyclic A/D-conversion, the output bits are generated cyclically, one by one. According to the inventive Gray coding algorithm, the analog input signal is cyclically subjected to a sample and hold operation, selectively, depending on the previously generated output bit, to a signal inversion, to an amplification by two, and to an addition of a predetermined reference signal. In a cyclic A/D-converter architecture based on the recursive Gray coding algorithm according to the invention, the accumulation of offset errors will generally be very low. Furthermore, the fact that the signal inversion is digitally controlled enables high precision implementations which further improve the performance of the cyclic A/D-converter according to the invention.