"That's why you have not seen much in the way of additional follow through in dollar demand."
Investors are focused on U.S. consumer price index and retail sales data, due on Friday, Lien said.
The dollar was 0.02 percent higher against the yen. The euro was little changed against the dollar after falling sharply on Wednesday.
"There is some speculation that the ECB is going to start hinting at reducing its stimulus and possibly ending its quantitative easing program," said Sireen Harajli, FX strategist at Mizuho, citing news that European Central Bank President Mario Draghi may address the Jackson Hole central banking conference next month.
"I think that's been supportive for the euro."
Yellen's testimony boosted the appeal of the higher yielding currencies. The New Zealand dollar was up 0.83 percent on Thursday against the greenback and the Australian dollar gained 0.7 percent.
The Canadian dollar edged higher against its U.S. counterpart, a day after the Canadian central bank raised interest rates for the first time since 2010. Canada.
Sterling rose for a second straight day against the greenback and was up 0.05 percent to $1.2942.