In this paper, a "composite" source-follower is presented. Using a positive-feedback, the structure synthesizes complex poles with a single branch. This allows to realize a single-branch biquadratic cell. Moreover, due to the intrinsic feedback present in any source-follower, the proposed cell performs larger linearity for smaller Vov(= VGS -V TH). This is the opposite of other active filters and allows saving the power otherwise used to increase linearity. A fourth-order prototype satisfy typical WLAN 802.11.a/b/g baseband filter specifications has been realized in a 0.18 μm CMOS at 1.8-V supply. It achieves a 17.5-dBm IIP3 and a -40 dB HD3 for a 600-mVpp_diff input signal amplitude. A 24-μVrms noise gives a DR = 79 dB, with 2.25-mA current consumption. © 2006 IEEE.
D'Amico, S., Conta, M., Baschirotto, A. (2006). A 4.1-mW 10-MHz Fourth-Order Source-Follower-Based Continuous-Time Filter With 79-dB DR. IEEE JOURNAL OF SOLID-STATE CIRCUITS, 41(12), 2713-2719 [10.1109/JSSC.2006.884191].
A 4.1-mW 10-MHz Fourth-Order Source-Follower-Based Continuous-Time Filter With 79-dB DR
BASCHIROTTO, ANDREA
2006
Abstract
In this paper, a "composite" source-follower is presented. Using a positive-feedback, the structure synthesizes complex poles with a single branch. This allows to realize a single-branch biquadratic cell. Moreover, due to the intrinsic feedback present in any source-follower, the proposed cell performs larger linearity for smaller Vov(= VGS -V TH). This is the opposite of other active filters and allows saving the power otherwise used to increase linearity. A fourth-order prototype satisfy typical WLAN 802.11.a/b/g baseband filter specifications has been realized in a 0.18 μm CMOS at 1.8-V supply. It achieves a 17.5-dBm IIP3 and a -40 dB HD3 for a 600-mVpp_diff input signal amplitude. A 24-μVrms noise gives a DR = 79 dB, with 2.25-mA current consumption. © 2006 IEEE.
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