A highly-efficient CMOS line driver with 80 dB linearity for ISDN U-interface applications

A line driver with a high-swing output stage is reported. The prototype, in a 0.9- mu m CMOS technology, is capable of delivering 9 V/sub pp-diff/ with 80 dB linearity operating from a single 9 V/sub pp-diff/ 5 V supply. The nearly rail-to-rail voltage swing results in 30% to 40% power reduction. The line driver prototype is operated from a single 5-V supply and occupies an active area of 0.63 mm/sup 2/ in a 0.9- mu m CMOS technology. The measured output spectrum in response to a 40-kHz sinusoid exhibits a third harmonic distortion component at the -83 dB level for 7 V/sub pp-diff/ output voltage. The total harmonic distortion as a function of output voltage is shown. Excellent linearity is maintained up to the onset of clipping (rail-to-rail voltage swing), even under the worst-case load.<>