High Pass Filter Implementation Comparison in Unity STF High Pass $\Delta \Sigma$ Modulator

Abstract : High-pass (HP) delta-sigma (ΔΣ) modulators enjoy superiority over low-pass (LP) ΔΣ modulators because of their inherent immunity to low-frequency noise. HP filter is a major building block of HP ΔΣ modulator. This article presents three state of the art HP filters accompanied by their detailed comparative analysis. They are compared on the basis of switch noise, Operational Transconductance Amplifier (OTA) noise and OTA finite dc-gain, finite gain-bandwidth product (GBW) and finite slew rate (SR). This in-depth analysis is validated by simulation results and proves that the improved structure provides superior performance than the other two HP filter implementations. It achieves better noise immunity and relaxes the OTA requirements.