A 91.2dB-SNDR 250kHz-BW CT Zoom ADC Achieving a 6-Bit Linear Zoom-in with Interstage LPF and 1.5-Bit DAC

This paper presents a continuous time (CT) zoom ADC that achieves a 6-bit linear zoom-in with an interstage LPF and an intrinsically linear 1.5-bit DAC. By using the interstage LPF, the shaped residue signal of the coarse <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Delta\Sigma \mathrm{M}$</tex> is properly filtered, enabling 6-bit linear zoom-in, boosting the SQNR by <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$&gt; 36\text{dH}$</tex>. Fabricated in 28nm CMOS process, the ADC consumes only <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$392\mu \mathrm{W}$</tex> while achieving 101.F 4dB SFDR, 91 2dB SNDR, and 92. 7dH DR in a signal bandwidth of 250kHz. This corresponds to a state-of-the-art FoM of 180. 7dB.