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-VTH ). 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 0.18um CMOS at 1.8-V supply. It achieves a 17.5-dBm IIP3 and a -40dB HD3 for a 600-mVpp_diff input signal amplitude. A 24-uVrms noise gives a DR = 79 dB, with 2.25mA current consumption.
A 4.1-mW 10-MHz Fourth-Order Source-Follower-Based Continuous-Time filter with 79-dB DR
D'AMICO, STEFANO;
2006-01-01
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-VTH ). 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 0.18um CMOS at 1.8-V supply. It achieves a 17.5-dBm IIP3 and a -40dB HD3 for a 600-mVpp_diff input signal amplitude. A 24-uVrms noise gives a DR = 79 dB, with 2.25mA current consumption.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
