Applied Micro Circuits Corporation

David S Rosky

Bruce H Coy

A method and apparatus for providing ECL output signals to a capacitative load includes differential amplification of input signals with a first output of a differential amplifier connected for establishing a voltage level between voltage limits V.sub.cc and V.sub.ee at the output of an output driver in response to variations in the first amplifier output. A pull-down transistor has a collector connected to the output driver output, an emitter connected to the V.sub.ee voltage source, and a base coupled through a boost capacitor to the second amplifier output. A voltage clamp embracing a clamp transistor with a base connected to receive a predetermined control voltage has an emitter connected to the boost capacitor and the pull-down transistor base and a collector connected to the V.sub.cc voltage source. The clamp transistor is operated in Darlington configuration to provide a minimum discharge impedence to the base of the pull-down transistor. A recovery capacitor is connected between the clamp transistor base and the first duplifier output to speed up the clamp transistor's operation.

Method and apparatus for coupling an ECL output signal using a clamped

A method and apparatus for providing ECL output signals to a capacitative load includes differential amplification of input signals with a first output of a differential amplifier connected for establishing a voltage level between voltage limits V.sub.cc and V.sub.ee at the output of an output driver in response to variations in the first amplifier output. A pull-down transistor has a collector connected to the output driver output, an emitter connected to the V.sub.ee voltage source, and a base coupled through a boost capacitor to the second amplifier output. A voltage clamp embracing a clamp transistor with a base connected to receive a predetermined control voltage has an emitter connected to the boost capacitor and the pull-down transistor base and a collector connected to the V.sub.cc voltage source. The clamp transistor is operated in Darlington configuration to provide a minimum discharge impedence to the base of the pull-down transistor. A recovery capacitor is connected between the clamp transistor base and the first amplifier output to speed up the clamp transistor's operation.

A method and apparatus for converting input signals at one predetermined logic level to output signals at corresponding different logic levels includes differential amplification of input signals with a first output of a differential amplifier connected for establishing a voltage level between voltage limits V.sub.cc and V.sub.ee at the output of an output driver in response to variations in amplifier output. A pull-down transistor has a collector connected to the output driver output, an emitter connected to the V.sub.ee voltage source, and a base capacitively coupled to the second amplifier output. In further aspects of the invention, a voltage clamp embracing a transistor with a base connected to receive a predetermined control voltage has an emitter connected to the pull-down transistor base and a collector connected to the V.sub.cc voltage source.

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Leucadia, CA, United States of America

David S Rosky