An efficient CMOS line driver for 1.544-Mb/s T1 and 2.048-Mb/s E1 applications

A CMOS operational amplifier (OPAMP) for use as a line driver for high-speed T1/E1 data communication link is described. The differential output swing, using a single 3.3-V power supply, is 5.2-V peak-to-peak on a 20-/spl Omega/ load. Novel circuits are used to control the closed-loop output impedance, quiescent bias current, and frequency compensation to ensure stable operation over varying temperature and load conditions. A special circuitry tristates the output in case of power-supply failure. The OPAMP achieves a unity-gain bandwidth of 35 MHz with only 10 mA of quiescent current. A new output-current-sense circuitry is used to provide a current feedback to adjust the output impedance for proper line termination as well as to provide short-circuit protection from excessive output currents. Using 0.35-/spl mu/m n-well CMOS technology, the amplifier occupies 0.69 mm/sup 2/ of area.