Integration Associates Incorporated

Elantec, Inc.

Stephen F Colaco

Wayne Thomas Holcombe

Brian Ben North

Pierre R Irissou

Edward C Bee

A PIN photodiode and method for forming the PIN photodiode are shown where an intrinsic layer of the photodiode can be made arbitrarily thin and a second active region of the photodiode substantially shields a first active region of the photodiode. A fabrication substrate is lightly doped in order to form the intrinsic layer of the photodiode. A void is formed in a first surface of the fabrication substrate and a first active region of the photodiode having a first conductivity type is formed in the void. An oxide layer is also formed upon the first surface of the fabrication substrate. A handling substrate is bonded to the first surface of the fabrication substrate. A second surface of the fabrication substrate is then lapped to a obtain a preselected thickness of the intrinsic layer. A depth of the void is selected such that a portion of the first active region is exposed at the second surface of the fabrication substrate after lapping. A second active region of the photodiode having a second conductivity type is formed on the second surface of the fabrication substrate. The second active region may be formed such that it substantially surrounds the exposed portion of the first active region. A low resistance contact to the exposed portion of the first active region is formed, where the area of contact is small. Also, dummy differential contact can be formed on the topside of the photodiode adjacent to the low resistance contact for use with a differential input receiver circuit. Further, separate second active regions may be formed, with separate contacts and one of the regions covered by an opaque layer, to obtain a differential photodiode.

Shielded planar dielectrically isolated high speed pin photodiode and method for producing same

Disclosed is a front end circuit involving a transimpedance amplifier that drives a resistor, thereby lowering the input impedance of the circuit by dividing the feedback resistance by the gain of the amplifier. In the front end circuit of the present invention, a first transistor is coupled in series with a resistor, where the received signal is input to a base or gate of the first transistor and the amplified received signal is recovered from a collector or drain of the first transistor such that the first transistor and resistor provide the gain of the front end circuit. A second transistor has an emitter or source coupled to the base or gate of the first transistor. A base or gate of the second transistor is coupled to the collector or drain of the first transistor and a collector or drain of the second transistor is coupled to a power supply rail. The second transistor thus provides the feedback path for the transimpedance amplifier thereby reducing the input impedance of the circuit.

Photodiode transimpedance circuit

An integrated active filter and sync separator circuit operates on precision internal reference sources to set the filter cut off frequency as a function of resistance of an external resistor. The active filter eliminates the source of sync tip crushing attributable to conventional clamping circuits associated with sync pulse detectors, and also provides sync pulses substantially devoid of time-variant jitter.

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Santa Cruz, CA, United States of America

Stephen F Colaco