A 144 crosspoint switching matrix

The description of this matrix and a discussion of the technology choices are presented. Packaged on a 25 mm square ceramic module, the 4.3/spl times/4.1 mm chip uses a junction isolation crosspoint design fully electrically compatible with its predecessor single-chip crosspoint. A ver low (3/spl times/10/SUP -4/) fraction of the device current is diverted to ground. This is obtained without any additional semiconductor processing steps. Matrix configurations using up to 144 crosspoints are defined by personalization wiring of 2 layers of metal. By comparison with the single crosspoint chip, the additional insertion loss is shown to be negligible and the crosstalk attenuation is improved. On a 760 telephone line system using these chips in a one-wire unbalanced network, the authors measured across the 300-4000 Hz band a maximum insertion loss of 1 dB and a crosstalk of 78 dB (at 4000 Hz) for the worst path and 87 dB for a typical path.