Abstract: A multi-bit continuous-time sigma-delta analog-to-digital converter (ADC) has a differential input stage which receives an analog input signal current. A multi-bit feedback current digital-to-analog converter (IDAC) generates a multi-level feedback current depending on a digital feedback signal from a flash ADC. An integrator has a differential input that integrates the difference of the generated current by the multi-bit IDAC and the input signal current on a continuous-time basis. The input stage further comprises a first biasing current source and a second biasing current source which bias the input stage in a mid-scale condition. A first summing node connects to the first differential input line, a first differential input of the integrator and the first output branch. A second summing node connects to the second differential input line, a second differential input of the integrator and the second output branch.

Abstract: A sigma-delta digital-to-analog converter comprises a current digital-to-analog converter (IDAC) stage which generates a current depending on an input digital signal. An output current-to-voltage converter converts the generated signal to a voltage on a continuous-time basis. The amplifier used in the output current-to-voltage converter is chopper-stabilized. The converter can be single bit or multi-bit. The IDAC stage can be implemented with a pair of branches, a first branch comprising a first biasing current source and a second branch comprising a second biasing current source. The biasing current sources can be chopper-stabilized by connecting the bias current sources to the output current-to-voltage converter by a set of switches. The switches connect the biasing current sources to the output current-to-voltage converter in a first configuration and a second, reversed, configuration. This modulates flicker noise contributed by the bias current sources to the chopping frequency.

Abstract: A method is provided for manufacturing a housing for containing an IC card. The method includes the steps of stamping a pair of metal covers with at least one of the covers having a continuous uninterrupted edge provided with a plurality of through holes spaced inwardly of and along the edge. The covers are placed into a mold for an injection molding process. Plastic support members are injected into the mold into attachment with the covers. Plastic material of the support member surrounds the edge and flows through the holes of the cover. The covers and attached support members are removed from the mold, and the support members are bonded together so that a housing is formed with the covers and within which the IC card can be contained.

Abstract: A card reader is provided for a chip card having card contacts. The card reader includes a housing having a card receiving mouth and a plurality of receptacle contacts having resilient contact portions for engaging the card contacts after the card is inserted through the mouth to a fully inserted position. An actuator is movably mounted on the housing for movement between an inoperative position and an actuating position. In the inoperative position, the actuator allows the card to be inserted past the contact portions toward its fully inserted position with substantially zero force on the contact portions. In the actuating position, the actuator biases the card contacts into engagement with the contact portions of the receptacle contacts. The actuator includes a biasing portion for biasing the card and the card contacts against the contact portions of the receptacle contacts.