Current-steering pre-emphasis transmitter with continuously tuned line terminations for optimum impedance match and maximum signal drive range

A 24-segment current-steering transmitter with 3-tap pre-emphasis and linear auto-tuned active line terminations is presented. A linearized resistor-MOSFET termination structure for continuous impedance tuning is proposed to maintain an accurate output voltage level (σ=1%) and good impedance matching (σ=2%). This enables larger signal drive strengths thanks to more efficient supply utilization. The circuit is implemented in 0.16 μm CMOS technology for data rates up to 6 Gbps and consumes 5-43 mA from a 1.8V supply for 50-1200 mVppd output signal.