Low-distortion bandpass ΣΔ modulator using two-path double-sampling technique

Abstract

A low-distortion bandpass (BP) sigma-delta (ΣΔ) modulator with double-sampling technique is proposed. The proposed modulator is based on a double-delay switched-capacitor resonator which employs double-sampling technique to relax the requirements for circuits and reduce amplifier power consumption and chip area. The proposed architecture can be applied for other modulators. The full differential circuit using two-path technique is designed with a standard 0.18 µm CMOS technology. The power consumption is 6 mW with 1.8 V supply. The fourth-order single-bit BP modulator achieves a peak SNR (signal-to-noise ratio) of 86.6 dB and DR (dynamic range) of 90 dB with 200 kHz bandwidth centered at 20 MHz which are better than the conventional BP ΣΔ modulator.