Abstract: A low power passive .SIGMA..DELTA. converter for baseband applications and with a built in mixer for direct conversion. For direct conversion, low power consumption is achieved by adopting a passive loop filter for the .SIGMA..DELTA. converter together with merging the sampling and mixing functions together utilizing a specially designed mixer. With a passive loop filter, the only gain element in the loop is a high gain, high speed, low noise comparator. The mixer can be located outside of the feedback loop, although according to one aspect of the present invention, the mixer is incorporated inside the feedback loop. For baseband applications, the same design is utilized with a simple sampling switch instead of a mixer for processing baseband signals with low power consumption.

Abstract: A switched-capacitor gain-boost network includes a bank of N-substantially identical sampling capacitors connectable to an output node. An integrating capacitor has one node connected to a low potential node and a second node connected to the output node. The integrating capacitor is connected to the bank of sampling capacitors in parallel when the bank of sampling capacitors is connected to the output node. Sampling period switches are actuable during a sampling period to connect the sampling capacitors of the bank in parallel and to connect the bank between an analog signal input node and a low potential node to charge the sampling capacitors. Integrating period switches are actuable during an integrating period to connect the sampling capacitors of the bank in series and to connect the bank between a low potential node and the output node to dump the charge stored by the sampling capacitors onto the integrating capacitor. A method of providing dc gain to an analog input signal is also provided.

Abstract: A Sigma-Delta converter, has a receiver for receiving an input digital signal; a digital loop filter and quantizer having an input and an output; a summer having a first input connected to the receiver, a second input connected to the output of the digital loop filter and quantizer, and an output connected to the input of the digital loop filter and quantizer for subtracting from the input digital signal an output digital signal from the digital loop filter and quantizer, and in response generating a difference signal for application to the input of the digital loop filter and quantizer; and a digital-to-analog converter having a plurality of unit elements with minor mismatching therebetween, for receiving and converting to analog the output digital signal from the digital loop filter and quantizer, and in response generating an output analog signal, wherein the digital-to-analog converter has a selector for cyclically selecting successive different permutations of the unit elements for converting each value