Device for generating a bit line selection signal of a memory device
The device for generating the bit line signal to enable a column transistor that is connected to a bit line and a local line in a semiconductor memory device includes at least a column decoder and a chain of connected inverters. The column decoder decodes a column address signal. The chain of connected inverters has an input terminal for receiving a first signal outputted from the column decoder and an output terminal for outputting a second signal to drive the column transistor. The second signal voltage is held substantially same as the first signal voltage for a predetermined time. After the predetermined time, the second signal voltage is held at a higher voltage than the first signal voltage to improve the current driving capacity of the column transistor. This increases the transmission speed of the signal transmitted from the bit line to the local input/output line.
1. A device for generating a bit line selection signal for enabling a column transistor connected to a bit line and a local input/output line in a semiconductor memory device, comprising:
a column decoder for decoding a column address signal received during a read operation; and
a chain of connected inverters having an inverter chain input terminal for receiving a first signal outputted from the column decoder and having an inverter chain output terminal for outputting a second signal to drive the column transistor,
wherein the voltage of the second signal is held substantially same as the voltage of the first signal for a predetermined time, and
wherein, after the predetermined time, the voltage of the second signal is held at a higher voltage than the voltage of the first signal to improve the current driving capacity of the column transistor and to increase the transmission speed of the signal transmitted from the bit line to the local input/output line.
2. The device according to claim 1 , wherein the column decoder comprises:
a NAND gate for receiving a column address signal; and
an inverter connected to the NAND gate for outputting the first signal based on the output signal of the NAND gate,
wherein the driving voltage applied to the NAND gate and the inverter substantially equals the voltage of the first signal.
3. The device according to claim 1 , wherein the chain of inverters comprises an even number of serially connected inverters and the driving voltage applied to the chain of inverters substantially equals the voltage of the second signal.
4. The device according to claim 3 , wherein the predetermined time is determined by the number of serially connected inverters in the chain.
5. The device according to claim 4 , wherein the total duration in which the first and second signals are outputted from the inverter chain output terminal to the gate transistor is substantially determined by the duration of the column address signal being applied to the column decoder.