Credence Systems Corporation

Robert R Hale

Paul Dana Wohlfarth

Bryan J Dinteman

Travis Scott Ellis

A relay includes contacts residing within a glass tube. A coil surrounding the tube and a switch are connected in parallel between two terminals of the relay. A current source supplies a current to the coil and switch. When the switch is open, substantially all of the current passes through the coil and the coil produces a sufficient amount of magnetic flux to close the relay's contacts. When the switch closes, it shunts a sufficient amount of the current away from the coil to reduce the magnetic flux it produces below the level needed to keep the contacts closed. The current source is sized so that the coil requires relatively few turns, thereby allowing the relay to be relatively thin. The coil is formed by a conductor embedded in an insulating substrate surrounding the tube.

Low profile, current-driven relay for integrated circuit tester

When turned on by an input CONTROL signal, a MOSFET transistor switch in accordance with the present invention connects a low impedance voltage source to a moderate to high impedance load. The switch includes a relatively large first MOSFET transistor (Q1), a smaller second MOSFET transistor (Q2), a resistor and a current source. Source terminals of transistors Q1 and Q2 are tied to the voltage source. The load is connected to the drain of Q1 while the current source is connected to the drain of the Q2 and also to the gates of both transistors Q1 and Q2. The resistor links the gates of transistors Q1 and Q2 to the voltage source. When the CONTROL signal is asserted, it turns on the current source, thereby quickly turning transistors Q1 and Q2 on to connect the voltage source to the load. When the control source is de-asserted, the current source turns off. Transistors Q1 and Q2 then turn off at a controlled rate in order to minimize current injection into the load.

Low charge injection mosfet switch

A differential driver includes an input stage and an output stage. The input stage receives a differential INPUT signal to produce a differential DRIVE signal of state determined by the INPUT signal. The output stage receives the DRIVE signal and produces a differential OUTPUT signal of state determined by the DRIVE signal. The OUTPUT signal voltage can be adjusted within any of multiple ranges. The output stage adjusts its output load resistance for each OUTPUT signal voltage range in order to maximize operating speed while limiting power consumption in each range. The input stage automatically reduces the voltage of the DRIVE signal input to the output stage for low OUTPUT signal voltages to reduce noise in the OUTPUT signal.

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Beaverton, OR, United States of America

Robert R Hale