Wolfgang Steinhagen

A low-power transponder IC for high-performance identification systems

A novel CMOS integrated circuit for a batteryless transponder system is presented. Batteryless transponders require contactless transmission of both the information and power between a mobile data carrier and a stationary or handheld reader unit. The operating principle of this system gives a superior performance in reading distance due to separation of the powering and data transmission phases-compared to systems with continuous powering and damping modulation. This paper describes the function of the transponder IC and the circuit design techniques used for the various building blocks. >

An adaptive biasing one-stage CMOS operational amplifier for driving high capacitive loads

An adaptive biasing one-stage CMOS operational amplifier for driving high capacitive loads has been developed. The amplifier has been designed to drive liquid-crystal-displays (LCDs) in battery-supplied devices. Contradictory features like low power dissipation and high driving capability at low supply voltage are required. Complementary differential input stages provide rail-to-rail common-mode input range. With a special cross-coupled double-to-single-end conversion, a full supply output range is achieved. These improvements solve a functional problem of some existing adaptive biasing amplifiers. Simulation and measurements demonstrate good correlation and show the expected results, especially in the critical operating area. >