The StrongARM Latch A Circuit for All Seasons

The StrongARM latch topology finds wide usage as a sense amplifier, a comparator, or simply a robust latch with high sensitivity. The term “StrongARM” commemorates the use of this circuit in Digital Equipment Corporation’s StrongARM microprocessor 1, but the basic structure was originally introduced by Toshiba’s Kobayashi et al. 2. The StrongARM latch has become popular for three reasons: 1) it consumes zero static power, 2) it directly produces rail-to-rail outputs, and 3) its input-referred offset arises from primarily one differential pair. In this column, we study the circuit and its properties.