Data output buffer and memory device
AssigneeSamsung Electronics Co., Ltd.
InventorsSi-Hong Kim, Seung-Jun Bae, Jin-Il Lee, Kwang-Il Park
Life of this patent
Estimating the term…
Abstract
A data output buffer includes a driving unit and a control unit. The driving unit selectively performs a termination operation that provides a termination impedance to a transmission line coupled to an external pin, and a driving operation that provides a drive impedance to the transmission line while outputting read data. The control unit adjusts a value of the termination impedance and a value of the drive impedance based on an output voltage at the external pin during a termination mode, and controls the driving unit to selectively perform one of the termination operation and the driving operation during a driving mode.
Claims24
A data output buffer of a memory device, comprising:
- an external pin coupled to a transmission line;
- a driving unit coupled to the external pin and configured to selectively perform a termination operation that presents a termination impedance to the transmission line via the external pin and a driving operation that presents a drive impedance to the transmission line while read data is output to the transmission line via the external pin, wherein the driving unit comprises;
- a pull-up driver coupled between a supply voltage and the external pin, and having a pull-up driver impedance that varies with a pull-up driving code;
- and
- a pull-down driver coupled between the external pin and a ground voltage, and having a pull-down driver impedance that varies with a pull-down driving code;
- a control unit configured to adjust a value of the termination impedance and a value of the drive impedance based on an output voltage apparent at the external pin during a termination mode of operation for the memory device, and to control the driving unit to selectively perform either the termination operation or the driving operation;
- a calibration unit configured to respectively generate a pull-up calibration code and a pull-down calibration code by comparing the output voltage with a reference voltage in response to a first calibration signal and a second calibration signal;
- and
- a switching unit configured to generate the pull-up driving code and the pull-down driving code based on the pull-up calibration code, the pull-down calibration code, a pull-up ZQ code and a pull-down ZQ code.
A method of operating a data output buffer of a memory device, the memory device being capable of operating in a write mode during which externally provided data is provided to an external pin via a transmission line and in a read mode during which read data is provided by the memory device to the external pin, the method comprising:
- during the write mode and the read mode, comparing an output voltage apparent at the external pin with a reference voltage;
- generating a pull-up driving code in response to the comparison of the output voltage and reference voltage and a pull-up calibration code, and applying the pull-up driving code to control a pull-up driver;
- generating a pull-down driving code in response to the comparison of the output voltage and reference voltage and a pull-down calibration code, and applying the pull-down driving code to control a pull-down driver;
- by operation of at least one of the pull-up driver and pull-down driver, presenting a termination impedance to the transmission line at the external pin during the write mode, and presenting a drive impedance, different from the termination impedance, to the transmission line at the external pin during the read mode, wherein a value of the termination impedance is adjusted in real time during the write mode, and a value of the driving impedance is adjusted in real time during the read mode.
A data output buffer of a memory device, wherein the memory device is capable of operating in a write mode during which externally provided data is provided to an external pin via a transmission line and in a read mode during which read data is provided by the memory device to the external pin, the data output buffer comprising:
- a driving unit including a pull-up driver and a pull-down driver coupled to the external pin and configured to present a termination impedance during the write mode, and a drive impedance, different from the termination impedance, during the read mode;
- a control unit configured during the write mode and the read mode to compare an output voltage apparent at the external pin with a reference voltage, generate a pull-up driving code applied to the pull-up driver in response to the comparison of the output voltage and reference voltage and a pull-up calibration code, and generate a pull-down driving code applied to the pull-down driver in response to the comparison of the output voltage and reference voltage and a pull-down calibration code,
- wherein a value of the termination impedance is adjusted in real time during the write mode, and a value of the driving impedance is adjusted in real time during the read mode by at least one of the pull-up driving code and the pull-down driving code.
Dependencies are inferred from the claim text.