Texas Instruments Corporation

George L Streckmann

Dennis Lee Doane

Paul Gerald Barker

Ralph A Harris

Anthony S Leonard

David V Dudasko

Donald E Russell

Jerry W Yancy

A visual inspection system (10) and method for inspecting the operation of micromechanical devices. The system has a vision system (16), a vision system controller (18), a system controller (20), an illumination system (12), a digital signal processor and a mounting stage (22). The objects undergoing inspection, either wafers or devices, are mounted under the visions system. A probe card is engaged to the object and power is provided. The vision system (16) records which elements or devices on the object begin operating at that voltage. The voltage is then incremented and the process continues until a determination is made as to the objects operability. The system can also be adapted to inspect micromechanical spatial light modulators by generating images with the modulator and capturing them with the image system. The digital signal processor then analyzes the images while the vision system moves to the next object to be inspected.

Inspection system for micromechanical devices

A compound floating point amplifier for amplifying an analog signal for presentation to an analog-to-digital converter has two amplifying sections to achieve a wide dynamic range. A signal representative of the rate of change (slew) is derived from a differentiating circuit. The analog signal and the slew rate signal are combined and if both are below a predetermined threshold level, a single step amplification is made in a dual gain amplifier. If both signals are not below the threshold, then there is unity gain through the dual gain amplifier. A sample and hold circuit receives the output of the dual gain amplifier and stores it. Subsequently, the stored voltage is impressed on a binary ladder attenuator which provides a digital word output indicating the required amplification. The voltage stored in the sample and hold circuit is also impressed on a binary gain amplifier system and amplified in accordance with the digital word from the binary ladder attenuator. The dual gain amplifier provides an input to an adder, indicating the amount of the step amplification which is added to the digital word from the binary ladder attenuator to provide a digital word indicative of the overall gain of the compound floating point amplifier.

Compound floating point amplifier

An extended range sample and hold circuit for use in systems such as floating point amplifiers is disclosed. An input differential amplifier receives a varying analog signal which is passed by a transistor sample switch during a predetermined sample period to an integrating differential amplifier having a sample capacitor across its output and inverting input. The charge on the sample capacitor follows the input analog signal. The output of the integrating differential amplifier is connected to a nonlinear circuit which in turn is connected to the noninverting input of an output differential amplifier. The nonlinear circuit provides a resistive path for small signals so that a fraction of the voltage across the sample capacitor is presented at the input to the output differential amplifier. As the signal becomes larger, a nonlinear portion of the circuit provides a signal at the input to the output differential amplifier that approaches the charge on the sample capacitor at one extreme. As the signal becomes smaller, it approaches the fractional portion at the other. The output amplifier provides a feedback loop to the input amplifier. Also, a transistor switch identical to the transistor sample switch is connected to a capacitor identical to the sample capacitor and connected to the noninverting input of the integrating differential amplifier to assure that transistor switch capacitance charge transfer is equal on the inverting and noninverting inputs of the integrating differential amplifier.

Extended range sample and hold circuit

An optical slip ring provides optical communication between a pair of members free to rotate with respect to each other. These members may be a pair of optical fibers, an electrical conductor and an optical fiber or a pair of electrical conductors. One member is attached to a first mounting device and the other member is attached to a second mounting device. One optical receiver is positioned in the center of the first mounting device on a common axis of rotation with respect to the second mounting device. The other optical receiver is mounted on the second mounting device, positioned on the common axis of rotation. One optical emitter is mounted off center on the first mounting device and the other optical emitter is mounted off center on the second mounting device. The optical emitter mounted on the first mounting device is aimed at the optical receiver mounted on the second mounting device, and the optical emitter mounted on the second mounting device is aimed at the optical receiver mounted on the first optical device. Relative rotation between the members does not change the optical communication between the optical emitters and their respective optical receivers.

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Dallas, TX, United States of America

George L Streckmann