Impedance boosting techniques based on BiCMOS technology |
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Authors: | Hadri S. Leung B. |
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Affiliation: | Dept. of Electr. & Comput. Eng., Waterloo Univ., Ont.; |
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Abstract: | An impedance enhancement technique, based on a combination of bipolar and MOS devices, is presented. The technique uses negative active feedback action to boost the impedance level of a cascode circuit. This technique improves the gain of the conventional folded-cascode BiCMOS amplifier by the loop gain of the feedback loop. The BiCMOS-based impedance boosting circuit, compared to the CMOS version, offers the advantage of higher bandwidth together with higher output current capability. The SPICE simulations of a folded-cascode op amp based on this technique show that a 120 dB DC gain can be achieved. Application of the technique to a transducer resulted in a total harmonic distortion as low as 0.02% with 2 Vp-p input signals and an improvement of more than 10 dB in linearity, with respect to the case where no feedback was used |
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