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

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- RC /Active- $g_{m}$ - RC cells. The 0.18- $\mu \text{m}$ 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- $\mu \text{V}_{\mathrm {RMS}}$ input referred iB integrated noise. The SNR for a −40 dB HD 3 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 $\cdot ~\text{J}^{-1})$ , which favourably compares to the state-of-the-art active- RC analog filters.