This paper presents the design, electrical and optical measurements of a receiver for optical communications in 28 nm CMOS. Electrical measurements show an error-free transmission with a bit error rate (BER) of 10-12 up to 20 Gbps. Inductor-less peaking methods are used, thus the circuit is very compact. With only 0.0025 mm2, 13.6 mW power consumption, yielding 0.68 pJ/bit it is one of the smallest and most energy efficient receiver to this date for 20 Gbps data rate (DR). The receiver was bonded to a printed circuit board (PCB) and to a 14 Gbps, 850 nm photo diode. An error-free transmission over the optical link was obtained up to 17 Gbps with an input optical sensitivity of -4.3 dBm. The measured sensitivity at 15 Gbps is just -7.5 dBm and -8.4 dBm for 10 Gbps.