Driver's Output Calibration Method with DAC Insertion

The driver's output calibration method with the help of a digital-to-analog converter (DAC), inserted in driver”s output, is presented in this paper. As interface speeds increase, it is essential to ensure that the IO drivers are properly calibrated with the transmission lines to prevent signal reflections. It is vitally significant to have highly accurate performance after calibration in high-speed systems which is difficult to provide. In the proposed method the equivalent PVT compensated rise and fall slew rates are provided due to the highly accurate R-2R DACs in order to avoid functional failures after transmission line. On top of that, the number of fingers of pre-drivers are decreased about five times owing to DAC insertion, so the overall area of the driver is decreased as well. Also, the data dependence jitter (ddj) is reduced. The proposed method can be used in special input/output circuits of several standards such as Double Data Rate (DDR), Universal Chiplet Interconnect (UCI), Universal Serial Bus (USB), and Peripheral Component Interconnect (PCI).