The parallel-encoding or flash ADC design provides the fastest operation at the expense of high component count and high cost (figure 8.5).
Figure 8.5: A 3-bit, parallel-encoding or flash ADC.
The resistor network sets discrete thresholds for a number of comparators. All comparators with thresholds above the input signal go false while those below go true. Then digital encoding logic converts the result to a digital number.