2.2. Self-testable FRWC
To overcome the potential problem of a faulty FRWC
circuit being used undetected during test mode
operation, additional circuitry is introduced to make
the FRWC self-testable. Furthermore, the resultant
test structure can continue to function correctly in the
event of a single fault occurrence inside the proposed
self test circuitry.
As shown in Fig. 1, the self test circuit comprises
two simple resistor networks (working as voltage
dividers) and two sets of MOSFET switches (S1-6).
By closing the switches S4-6 one at a time, three
different voltage settings can be selected. For each
voltage selected, by closing the switches S1-3 one at a
time we managed to create three different test
conditions to represent a complete test cycle for the
FRWC. Table 1 shows the three test conditions: