Abstract: Nth-order OTA-C (Operational Transconductance Amplifiers and Capacitors) filter structures are realized by using the analytical synthesis method to achieve the following three important criteria simultaneously: filters use just n grounded capacitors, each of which is located at each of just n nodes in the realized circuit, because they use smaller area in the IC, and they can absorb equivalent shunt capacitive parasites; filters employ only single-ended-input OTAs to overcome the feed-through effects due to finite input parasitic capacitances associated with double-input OTAs to replace the same positions of the n given capacitors; and filters have the least number-of components (passive and active) for a given order to reduce power consumption, chip areas, and noise. Both the first and the second criteria lead to the minimum parasitic distortion and make the most precise output signals. And the third criterion produces the cheapest chip.

Abstract: The invention provides a base station for connection of a low-power and a high-power radio telephone network. The high-power radio telephone network comprises a first and a second terminal, while the low-power radio telephone network comprises a third terminal. The first terminal has a first interface for communication with an external device. The base station, which operates for the low-power radio telephone network, has a second interface compatible to the first interface, and communicates with the first terminal of the high-power radio telephone network through the connection of the first and second interface. Therefore, the third terminal of the low-power radio telephone network communicates with the second terminal of the high-power radio telephone network under the operation of the first terminal and the base station.

Abstract: A converter for providing an electrical signal according to the status of a light spot applied thereto, comprises: a sensor for sensing the light spot and generating a position current according to the position of the light spot sensed thereat; and an operating circuit for providing the sensor with an operating current when the light spot is sensed by the sensor and for outputting a status current corresponding to the operating current. The sensor comprises two electrodes each providing a current with magnitude determined according to the distance between it and the position of the light spot sensed thereat. The position current is obtained by subtracting the first electrode current from the second electrode current.

Abstract: A device and method capable of converting a position signal into a frequency signal using a photoelectric position sensitive detector is provided. The device capable of converting a position signal into a frequency signal comprises: a PSD, two current mirrors, a variable optimum constant current source, and a converter. The method capable of converting a position signal into a frequency signal comprises: providing a PSD, providing two current mirrors, providing a variable optimum constant current source, and providing a converter to convert a position signal into a frequency via a relationship.