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In this letter, we propose and demonstrate a compact, low-cost, and easy to manufacture microstrip line with two open-circuit stubs to alleviate impedance mismatching of a packaged 40-Gb/s electroabsorption modulator integrated laser (EML) module. For comparison, two 1550-nm EML modules are fabricated, the only difference being that one of them is made with open-circuit stubs, while the other is not. It is revealed that the open-circuit stubs technique expands the 3-dB modulation bandwidth from 25.2 to 33.6 GHz, and the suppression of the input return loss below -10 dB in the range of the higher frequency of the sub-assembly with chip is also successfully demonstrated. Further evidence showing the advantage of the EML module with open-circuit stubs over the one without open-circuit stubs include the effective reduction in the RMS jitter of the eye diagram from 1.4 to 1.2 ps, as well as the improvement of the sensitivity, which changes from -8.3 to -9.5 dBm measured with the same receiver.