Class AB CMOS amplifiers with high efficiency |
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Authors: | Callewaert LGA Sansen WMC |
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Affiliation: | Dept. Elektrotech., Katholieke Univ. Leuven, Heverlee; |
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Abstract: | A new class AB CMOS operational-amplifier principle is presented. A transconductance amplifier based on this principle exhibits small-signal characteristics comparable to those of a conventional OTA. It has, however, a superior current efficiency and its settling time is not slew-rate limited. The new class AB principle can also be used in an output stage with a well-defined quiescent current, a rail-to-rail output swing, and a good driving capability. A two-stage amplifier with both the input and output stages based on the new principle has been realized. It features a rail-to-rail input and output common-mode range, a gain-bandwidth of 370-kHz, a settling time of less than 5 μs independent of the applied step, and a power consumption of 247 μW. It drives a resistive load of 3 kΩ in parallel with a capacitive load of 400 pF when operated on a 2.5-V/-2.5-V power supply |
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