Semiconductor integrated circuit having low power consumption with self-refresh
View Patent ↗A dynamic random access memory has logically identical circuits for providing the same logical control signals. Each set of control signals can have different electrical parameters. One circuit can be optimized for high speed performance, while another circuit can be optimized for low power consumption. The logically identical circuits can include wordline address predecoder circuits, where a high speed predecoder circuit is enabled during a normal operating mode and a slower low power predecoder circuit is enabled for self-refresh operations. During self-refresh operations, the high speed circuit can be decoupled from the power supply to minimize its current leakage.
1. A mode dependent logic circuit for use in a dynamic random access memory, comprising:
a first circuit for generating a first address in a normal operating mode;
a second circuit logically identical to the first circuit for generating a second address logically identical to the first address in a sleep operating mode, the second circuit consuming less power than the first circuit, and
a selector for receiving the first address and the second address, the selector passing the first address in the normal operating mode and passing the second address in the sleep operating mode.
2. The mode dependent logic circuit of claim 1 , wherein the second circuit includes transistors having a higher threshold voltage than transistors of the first circuit.
3. The mode dependent logic circuit of claim 1 , wherein the first circuit includes a first power switch circuit for selectively disconnecting the transistors of the first circuit from VDD or VSS in the sleep operating mode.
4. The mode dependent logic circuit of claim 3 , wherein the second circuit includes a second power switch circuit for selectively disconnecting the transistors of the second circuit from VDD and VSS in a deep power down operating mode.
5. The mode dependent logic circuit of claim 1 , further including at least two first signal lines for providing the first input signal, and at least two second signal lines for providing the second input signal, the first and the second signal lines being interleaved with each other.
6. The mode dependent logic circuit of claim 5 , further including a first drive circuit coupled to the at least two first signal lines, and a second drive circuit coupled to the at least two second signal lines, the second drive circuit driving the at least two second signal lines to one of VDD and VSS in the first operating mode.
7. The mode dependent logic circuit of claim 4 , wherein the first power switch circuit disconnects the transistors of the first circuit from VDD or VSS in the deep power down operating mode.
8. The mode dependent logic circuit of claim 7 , wherein the second power switch circuit receives a deep sleep signal at an active logic level for selectively disconnecting the transistors of the second circuit from VDD or VSS in the deep power down operating mode, the deep sleep signal being at an inactive logic level in the sleep operating mode.
9. The mode dependent logic circuit of claim 8 , wherein the first power switch circuit receives a sleep signal at an active logic level for selectively disconnecting the transistors of the first circuit from VDD or VSS, the sleep signal being at the active logic level when at least one of the deep sleep signal and a sleep mode signal are at the active logic level.