Field programmable analogue arrays: a DFT view

The design for testability (DFT) of analogue and mixed signal electronic systems has much in common with the problem of Field Programmable Analogue Array (FPAA) design. The FPAA described here is offered as a model for analogue system DFT It gives direct access to internal nodes of the user circuit, it facilitates subdivision for modular test and it can reconfigure the circuit to comply with standard test usage. Special switching techniques are employed to prevent the DFT enhancement detracting from the performance of the circuit in service. A prototype of this FPAA architecture has been fabricated on standard CMOS and a summary of performance is presented.