A memory circuit includes a first memory cell, a second memory cell and a sense amplifier. The sense amplifier is coupled to the first memory cell by a first bit line, and coupled to the second memory cell by a second bit line. The sense amplifier includes a header switch, a footer switch, a first cross-coupled inverter and a second cross-coupled inverter. The header switch has a first size, and is coupled to a first node and a first supply voltage. The footer switch has a second size, and is coupled to a second node and a second supply voltage. The first size is greater than the second size. The first size includes a first number of fins or a first channel width. The second size includes a second number of fins or a second channel width.