A 3-bit flash analog-to-digital converter (ADC) for electronic dispersion compensation (EDC) was developed using lnP HBTs. Nyquist operation was confirmed up to 24 Gsps, which enables oversampling acquisition for 10 Gbit/s non-retum-to-zero (NRZ) signals. The ADC can also be operated at up to 37 Gsps for low input frequencies. To reduce aperture jitter and achieve a wide band of over 7 GHz, an analog input signal for all pre-amplifiers and a clock signal for all latched comparators are provided as traveling waves through coplanar transmission lines. EDC was demonstrated by capturing a 10-Gbit/s pseudo-random bit stream (PRBS) with the waveform degraded by polarization-mode dispersion (PMD). By using the captured data, we confirmed that a calculation of a transversal filter mitigates PMD.