The read process of all memory devices is common. After settling the predefined voltage to the bit line, the bit line is electrically connected with the memory cell. Then, the stored bit information of the cell will modulate the bit line voltage or current. The modulated analog value (voltage or current) of a bit line is then converted to the digital value (namely, GND or VDD) by the sense amplifier (SA) circuit.

Figure 4991. DRAM and its equivalent circuit models. [1]

[1] Krzysztof (Kris) Iniewski, CMOS Processors and Memories, 2010.