Agere Systems Guardian Corp.

John S Clapp

Glen A Johnson

Douglas Baird Lebo

Lawrence Peter Swanson

The present invention provides methods and apparatus for trimming semiconductor devices and circuits, such as pin electronics circuits used in automated test equipment (ATE) systems and the like, without requiring a laser trimming operation. In a preferred embodiment, the present invention addresses the need to precisely adjust a reference current and/or voltage by replacing a conventional current/voltage reference source with a digital-to-analog (D/A) converter. A select switch or mechanism is preferably coupled to the input of the D/A converter and operatively presents a digital input word to the D/A converter by selectively reading the digital word from at least one of a data register and a fuse register. The data register is preferably used during testing of the overall current or voltage reference by iteratively trying various digital input codes while concurrently measuring the analog output signal from the D/A converter until the output signal sufficiently matches a predetermined output value. The fuse register, which comprises a plurality of fusible links, is then preferably blown to permanently store the input code word that provides the desired reference output. During normal operation of the circuit, the select switch preferably reads the D/A converter input word from the fuse register. In this manner, a precise output reference signal is achieved without the need for laser trimming.

Apparatus and method for precision trimming of a semiconductor device

An emitter or source follower is added to a current mirror and, more particularly, to a cascoded current mirror that uses beta helpers to reduce the mirror error due to base currents for restoring a Vbe of voltage compliance to the cascoded current mirror, thus allowing the use of a cascoded current mirror in applications where it could not otherwise be used due to voltage compliance problems.

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Wyomissing, PA, United States of America

John S Clapp