We integrate a wavelength-tunable microring resonator with a monolithic Ge-on-Si photodetector for use as a variable bit-rate silicon receiver. The integrated receiver has a responsivity of 0.7 A/W. We achieved error-free operation for a wide range of bit rates from 5 Gb/s to 12.5 Gb/s. The wavelength tuning was realized by a TiN-based thermal heater, which enabled tuning of up to ~1 free spectral range.