A power management circuit in a low-power double data rate memory is configured to manage a plurality of power supplies memory according to a reference voltage. A low dropout regulator has a first transmitting terminal and a second transmitting terminal. The low dropout regulator adjusts a voltage difference between a first voltage and a second voltage according to the reference voltage. A power network structure is electrically connected to the low dropout regulator. A first power network circuit has a first connecting point, a grid shape and a first unit network space. A second power network circuit has a second connecting point, another grid shape and a second unit network space. The second connecting point is separated from the first connecting point by a distance. The distance is smaller than or equal to one of the first unit network space and the second unit network space.