Patent ID: 6894543

Claim:
A differential line driver comprising: a plurality of driver cells having common inputs Vip and Vin, and common outputs Vop and Von; and control logic that generates positive and negative control signals for controlling a combined output impedance of the driver cells at (Vop, Von), wherein each driver cell includes: a first transistor of a first polarity and a first transistor of a second polarity controlled by the input Vip; a second transistor of the first polarity and a second transistor of the second polarity controlled by the input Vin, wherein a source of the first transistor of the first polarity is connected to a source of the second transistor of the first polarity, and herein a source of the first transistor of the second polarity is connected to a source of the second transistor of the second polarity; first and second resistors connected in series between the first transistor of the first polarity and the first transistor of the second polarity, and connected together at the output Von; third and fourth resistors connected in series between the second transistor of the first polarity and the second transistor of the second polarity, and connected together at the output Vop; a first output switch controlled by a corresponding positive control signal and connected between a supply voltage and the sources of the first and second transistor of the first polaritys; and a second output switch controlled by a corresponding negative control signal and connected between a ground and the sources of the first and second transistors of the first polarity.