Any of these three stocks could be the backbone of a solid dividend portfolio.Building a portfolio of high-yield dividend stocks can set you up for a lifetime of passive income. But investing in dividend stocks is much more complex than simply picking the stock with the highest yield. Finding an ultra-high-yield dividend stock trading at a fair price that has the potential to keep raising its dividend is the key to unlocking sustainable passive income.Buying a handful of those stocks at a good value and hol ...