A fully differential line driver with on-chip calibrated source termination for gigabit and fast Ethernet in a standard 0.13μ CMOS process

A high performance, fully differential line driver for use in gigabit and fast Ethernet over unshielded twisted pair CAT-5 copper cables is presented. By using a negative feedback based technique and an on-chip calibration engine to compensate for process variations, the 100-ohm output impedance is synthesized. To date, this is the single industrial realization of a gigabit/fast Ethernet line driver that incorporates the source termination. The circuit is fabricated in a standard 0.13 μm CMOS process, occupies 0.06 mm² of area and consumes less than 8 mA of quiescent current under 3.3 V supply. Extensive laboratory tests proved that the line driver meets the prescriptions of IEEE standard 802.3-200 with consistent margins.