Patent ID: 6771097
Filing Date: 2004-08-03
Classification: H03K,H04L

Abstract:
A differential line driver comprising:a plurality of driver cells having a common input Vip and a common input Vin, and a common output Vop and a common output Von for driving a line; and control logic that generates positive and negative control signals for the driver cells so as to match a combined output impedance of the driver cells at (Vop, Von) to the line, wherein each driver cell includes: a first PMOS transistor and a first NMOS transistor having gates driven by the input Vip; a second PMOS transistor and a second NMOS transistor having gates driven by the input Vin, wherein a source of the first PMOS transistor is connected to a source of the second PMOS transistor, and wherein a source of the first NMOS transistor is connected to a source of the second NMOS transistor; first and second resistors connected in series between the first PMOS transistor and the first NMOS transistor, and connected together at the output Von; third and fourth resistors connected in series between the second PMOS transistor and the second NMOS transistor, and connected together at the output Vop; a first output switch driven by a corresponding positive control signal and connected between a supply voltage and the sources of the first and second PMOS transistors; and a second output switch driven by a corresponding negative control signal and connected between a ground and the sources of the first and second PMOS transistors.