Emerging market bond ETFs have grown in popularity the past year as investors broaden their horizons in the fixed-income markets in the search for yield.

However, a pair of emerging market debt ETFs in this fast-growing category has been beating the competition recently in terms of performance.

They are outperforming because they don’t hedge their foreign-currency exposure,and a strengthening U.S. dollar is providing a tailwind.

The iShares JP Morgan USD Emerging Markets Bond Fund (NYSEArca: EMB) and PowerShares Emerging Markets Sovereign Debt Portfolio (NYSEArca: PCY) avoid foreign-currency risk by investing in dollar-denominated debt.

Over the past three months, EMB and PCY have delivered total returns of 4.6% and 6%, respectively, according to Morningstar. WisdomTree Emerging Markets Local Debt (NYSEArca: ELD), which does not hedge its foreign-currency exposure, is flat over the same period.

EMB and PCY are getting a lift from a stronger U.S. dollar on Eurozone debt worries and a preference for safer currencies. PowerShares DB US Dollar Index Bullish (NYSEArca: UUP) is up 3.8% for the trailing three months. [Emerging Market Bond ETFs that Hedge Currency Risks]

EMB is larger in terms of assets with $4.8 billion. The fund has a 30-day SEC yield of 4.3%, according to manager BlackRock.

PCY, the PowerShares ETF, holds assets of about $2 billion and offers a 30-day SEC yield of 5%.