Peripheral Component Interconnect Express (PCIe) Transmitter Preset Coefficient Autotune Algorithm

Transmitter equalization plays a very important factor in Peripheral Component Interconnect Express (PCIe), which could cause bad data transfers in case poor quality of link equalization due to high frequency channel losses. Preset test is one of the electrical compliance tests that must pass in compliance workshop to formally label products as compliant. Currently, the tuning of the presets is done manually by engineers, which is time consuming and might not optimize to reach an ideal set of coefficients. In this paper, autotune process is introduced to predict the most optimized preshoot (PS) and deemphasis (DE) value for those preset that are marginal or not meeting the specification. By using the baseline measurement of PS and DE, the most optimized value based on the ideal calculation of each increment or decrement of PS and DE is predicted and feedbacked to the real measurement to verify. Experimental results show that the sample able to tune to a better optimized PS and DE value, allowing more than 25% margin from the upper and lower limit of specification.