The dollar was up 0.4 per cent to 113.05 yen after hitting the low of 112.57 yen, while the dollar index was at 100.50, up 0.2 per cent, according to Reuters.
Yellen could reveal information on the direction of policies today in her speech to the Commonwealth Club in San Francisco.
San Francisco Federal Reserve Bank President John Williams said he sees a "good case" for three rate hikes this year, Reuters reported. He added if the economy accelerates, the Fed would need to raise rates faster.
Sterling fell 0.6 per cent to $1.2341 after making its largest one-day gain in years following a speech from Theresa May where she revealed more details on her plans for Brexit.
Markets had already priced in the prospect of the UK leaving the Single Market to a large extent, after May strongly hinted at it in an earlier interview. Sterling had previously suffered a strong sell-off in the new year.