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.