An optically-coupled crosspoint array with high dv/dt capability and high gate sensitivity

Abstract

A 2/spl times/4 optically-coupled economical crosspoint array for the telephone speech path with a high breakover voltage (>450 V), high dv/dt capability (>200 V/0.1 /spl mu/s), and high gate sensitivity (<5 mA) is described. This has been achieved by a new device structure with a double-gate MOSFET and RC discharge circuitry formed on a p-n-p-n element. This MOS associated circuitry for dv/dt improvement is referred to as `MAC' p-n-p-n elements with MAC can be separated from each other with a new simple isolation technique called `canal isolation' which facilitates low manufacturing cost. Both p-n-p-n elements and LEDs are bonded face-down on a 44 pin chip carrier ceramic package with bump electrodes which again allows low manufacturing cost. The MAC enables independent control of the dv/dt capability and the gate sensitivity. The authors show the MAC performance in dv/dt improvement and various evaluations of MAC, including computer simulation. High breakover voltage technology and some processes for forming the gate-to-cathode resistor R/SUB GK/ for devices with MAC are discussed. This new optically-coupled crosspoint array with MAC makes possible a high-performance direct interface with conventional telephone sets.