530V Integrated gated diode switch for telecommunications

The objective of this work is to develop a new solid state crosspoint switch for telecommunications circuits. The switch is fully integrated into 580V monolithic circuits with appropriate control circuitry. Integrated arrays, packaged in hermetic chip carriers, perform the high level line circuit switching functions previously realized with arrays of electro-mechanical crosspoints. The Gated Diode Switch (GDS) is a dielectrically isolated lateral P⁺πPN⁺diode with a diffused gate on the planar surface and an MOS gate (consisting of the isolation oxide and polycrystalline substrate) on the lower boundary. With the center gate structure it achieves 530V bilateral blocking, very low crosstalk, insensitivity to transients and full current break capability. Two switches, each 0.15mm², can be connected in antiparallel to realize a bidirectional current capability of 120mA DC and 500mA surge. Electron and hole injection produces conductivity modulation in the π-type tub to realize an incremental on resistance of 18 ohms and a forward voltage of 1.7V at 30mA. The paper describes the properties of the GDS when it is maintaining the off state, turning on and breaking current. The paper also establishes the requirements this switch places on its integrated control circuit. Integrated arrays containing four pairs of bilateral crosspoint switches have been developed for the subscriber line interface circuits of a large digital electronic switching system, #5 ESS.