A CMOS line driver with 80-dB linearity for ISDN applications

A high-performance CMOS line driver for ISDN U-interface transceiver applications has been designed and fabricated. Careful study of requirements and trade-offs affecting linearity, power efficiency, and quiescent current presented in this work has resulted in a circuit structure featuring a highly linear input/output characteristic and well-controlled quiescent current. The prototype line driver is capable of delivering a 5-V/sub pp/ signal of up tp 80 kHz to a 60- Omega load while exhibiting linearity on the order of 77 +or- 5 dB and operating from a single 5-V power supply. Linearity better than 70 dB is maintained for load resistances as low as 20 Omega .<
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