But with two months until his inauguration and a rise in Fed interest rates now fully priced in for next month, several banks say the currency could drift.
Valentin Marinov, head of G10 FX strategy at Credit Agricole in London, said that Fed speakers this week had sounded divided on their view on the effective tightening of monetary conditions since Trump`s election.
"All eyes are on Yellen today," he said.
"She may not share markets` enthusiasm about the future impact of Trump`s policies. And she could express concern about the dollar`s rapid gains and the tightening of conditions through higher bond yields. That could spur some profit-taking on the bullish dollar positions."
In early trade in Europe, the greenback fell around 0.2 percent against the basket of currencies that measures its broader strength, a half point off almost 14-year highs hit on Wednesday.
It was flat on the day at 109.03 yen and 0.2 percent lower against the euro at $1.0709.
"I have been long the dollar against the euro for three days," said Louis Gargour, chief investment officer with hedge fund LNG in London.
"$1.05 is not out of the question. Will I be in the trade that long (until Trump`s inauguration), maybe not. Let`s look at the cabinet, let`s look at who he puts in place and whether his policy will be as good (for the dollar) as people expect."
The yen took a knock overnight when the Bank of Japan conducted its first special operation to curb rising yields on Japanese government bonds (JGBs). The offer was priced to attract no bids, but knocked government bond yields further back into negative territory, pushing the dollar briefly as high as 109.30 yen.
"Rises in U.S. yields have been a significant factor behind the dollar`s strength, but since that has started to calm down for now, moves in the dollar against yen have also settled down," said Shinichiro Kadota, a Tokyo-based FX strategist for Barclays.
The U.S. benchmark 10-year Treasury yield is now at 2.199 percent, after reaching a 10-month high of 2.302 percent earlier in the week.
Yellen testifies to the congressional Joint Economic Committee from 1500 GMT. [FED/DIARY]
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