Monolithic crosspoint arrays for private automatic branch exchanges (PABX)

This paper presents economical technical solutions for monolithic integrated semiconductor crosspoint arrays for PABXs. It starts with the description of IGFET switches and I/SUP 2/L-bipolar transistor switches. Then, realised symmetrical crosspoint arrays with these switches are treated, beginning with the integration level and the logic concept. Monolithic integrated crosspoint arrays with 5/spl times/2 balanced crosspoints in PMOS technology, NMOS Si-gate technology, and I/SUP 2/L technology are described in detail. Measurements for PMOS and I/SUP 2/L arrays show that for a one-stage PABX all transmission requirements at least are fulfilled. With an I/SUP 2/L-bipolar transistor array even switching networks with three stages are possible, since ON-resistances of these switches are especially low.