A hydraulic drive system for storing and releasing hydraulic fluid includes a high pressure storage device, a low pressure storage device, a pump operating at a range of pump speeds for converting between mechanical energy and hydraulic energy, and a motor operating at a range of motor speeds for converting between hydraulic energy and mechanical energy. The interlaced sampling method will harm the SNR of channel estimation only very slightly. The source structure is formed within the deep well and located at a first side of the gate structure.