Methods and apparatuses including a variable termination impedance ratio

摘要

Methods of changing a centerline voltage of a data signal are described, along with apparatuses to change the centerline voltage. In one such method, portions of a termination circuit coupled to an output pin are selectively activated to change an impedance of the termination circuit to change the centerline voltage of the data signal driven to the output pin. One such apparatus includes pull-up impedances and pull-down impedances that can be activated to change the centerline voltage of the data signal. Additional embodiments are also described.

主权项

1. A memory device comprising:
a memory array for storing data; a termination register configured to store termination values; a termination control circuit coupled to the termination register; and an I/O circuit, coupled to the memory array and the termination control circuit, for transmitting data from and receiving data to the memory array, the I/O circuit comprising a plurality of driver and receiver circuits, each of the plurality of driver and receiver circuits having an adjustable pull-up impedance and an adjustable pull-down impedance that are adjusted by the termination control circuit in response to the stored termination values wherein each adjustable pull up impedance and each pull down impedance comprises a plurality of resistance circuits coupled together in parallel, and the plurality of resistance circuits for the adjustable pull up impedance are coupled in parallel between an output pin of the memory device and a supply voltage node; a temperature sensing circuit configured to indicate a temperature of the memory device; and a control circuit, coupled to the termination register and the temperature sensing circuit, configured to write the termination values to the termination register and to adjust the termination values stored in the termination register in response to a change in the temperature of the memory device.