From a Bernanke speech in 2002 about deflation in Japan:

“Another option would be for the Fed to use its existing authority to operate in the markets for agency debt,'’ he said. It could offer “fixed-term loans to banks at low or zero interest, with a wide range of private assets, including, among others, corporate bonds, commercial paper, bank loans and mortgages deemed eligible as collateral.'’

“One approach, similar to an action taken in the past couple of years by the Bank of Japan, would be for the Fed to commit to holding the overnight rate at zero for some specified period,'’ Bernanke wrote. “A more direct method, which I personally prefer, would be for the Fed to begin announcing explicit ceilings for yields on longer-maturity Treasury debt, say, bonds maturing within the next two years.'’

The central bank would pledge itself to unlimited purchases of Treasury
notes to prevent yields from rising above a preset target level, Bernanke said. “If operating in relatively short- dated Treasury debt proved insufficient, the Fed could also attempt to cap yields of Treasury securities at still longer maturities, say three to six years.'’ (Bloomberg)

Here’s why it won’t work: The PBOC, BOJ, and any other unfortunate suckers will preemptively dump their holdings on the market if the Fed prints too much. At the same time, domestic investment will flee the country for stronger currencies faster than the Fed can print. We’re already seeing a preemptive CUB + dollar carry trade.