A memory circuit has a memory array with a first line of memory cells, a second line of memory cells, a first power supply terminal, a first capacitance structure, a first power supply line coupled to the first line of memory cells; and a second power supply line coupled to the second line of memory cells. For the case where the second line of memory cells is selected for writing, a switching circuit couples the power supply terminal to the first power supply line, decouples the first power supply line from the second line of memory cells, and couples the second power supply line to the first capacitance structure. The result is a reduction in power supply voltage to the selected line of memory cells by charge sharing with the capacitance structure. This provides more margin in the write operation on a cell in the selected line of memory cells.