A 63-dB DR 22.5-MHz 21.5-dBm IIP3 Fourth-Order FLFB Analog Filter

Abstract

In this paper, a fourth-order continuous-time follow-the-leader-feedback (FLFB) low-pass (LP) filter is presented. The outstanding FLFB noise behavior is exploited to minimize power consumption. This is achieved by means of customized implementation solutions based on combination of Active- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> /Active- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$g_{m}$ </tex-math></inline-formula> - <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> cells. The 0.18- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> CMOS prototype performs 22.5-MHz −3 dB LP frequency response. Large linearity and dynamic range were achieved resulting in 21.5-dBm in-band (iB) IIP3 and 87- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{V}_{\mathrm {RMS}}$ </tex-math></inline-formula> input referred iB integrated noise. The SNR for a −40 dB HD <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> is 63 dB. The overall power consumption is 12.6 mW (i.e., 7 mA from a 1.8-V supply). The efficiency of the proposed technique is demonstrated by the achieved figure-of-merit (150.8 dB <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot ~\text{J}^{-1})$ </tex-math></inline-formula> , which favourably compares to the state-of-the-art active- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> analog filters.