The structural testing of switched current designs

The switched current memory cell is a conceptually simple yet elegant building block which can be used to realise many analogue applications including: filters, data convertors and neural networks. The advantages of using switched current design over the more conventional switched capacitor realisations are numerous, more importantly, compatibility with digital circuit supply voltages. Furthermore the functionality of a switched current circuit offers the ability to incorporate a particularly simple design for test techniques, which reduces the test of the bulk of the circuit to comparison between identical sub-circuits. Early work concentrated on detecting catastrophic or hard faults on the component transistors. More recently this has been extended by simulating a variety of connectivity and soft faults including: bridging defects, floating gate faults, gate oxide faults and aspect ratio deviations. By taking layout based information into account an exponential information increase can be avoided as more fault types are introduced