Abstract: An impedance control circuit with either current-controlled or voltage-controlled feedback loops in a transmission system. The impedance can be set at desired values, including complex values, and be different at different frequencies. The circuit is particularly useful in subscriber line interface circuits in telephone systems.

Abstract: A new input protection device for integrated circuits in which the metal-semiconductor contact between a metal line from a metal input pad and doped semiconductor region in the substrate leading to the rest of the integrated circuit is significantly rounded. This reduces the tendency of high current densities to flow through specific areas of the contact creating a short-circuiting metal-semiconductor spike into the substrate. Furthermore, the contact is enlarged beyond the normal size of contacts within the integrated circuit and the conducting region below is formed deeper and laterally away from the contact for further protection.

Abstract: A marking element assembly including a yoke which is driven by an arm. The arm is connected to a slider block which transfers motion to the yoke. The yoke has an interior channel for slider block free motion, with drag, after a marking element connected to the yoke stops yoke motion. The slider block moves against interior walls of the yoke dissipating arm motion and providing shock absorption for the marking element.

Abstract: A battery feed circuit with a current-controlled feedback loop supplying DC current to a load. The circuit is particularly adjustable to telephone systems and is characterized by low power dissipation.

Abstract: A digital-to-analog converter is provided which converts a series of digital binary numbers into an analog signal having an amplitude proportional to the values of the binary numbers. The disclosed embodiment of this invention includes a segment generator having input terminals coupled to receive the most significant digits of the binary numbers to be converted, wherein the segment generator provides a first signal proportional to the values of the most significant digits of the binary numbers. A step generator is also included which receives the remaining lesser significant digits of the binary number and provides a second signal proportional to the values of these lesser significant digits of the same binary numbers. Additionally, means for combining the first and second signals is provided to form an analog signal proportional to the value of the binary number to be converted.