On the Use of FIR Feedback in Bandpass Delta-Sigma Modulators J. Gorji, S. Pavan and J.M. de la Rosa Journal Paper · IEEE Transactions on Circuits and Systems I: Regular Papers, 2023 abstractdoi
This paper presents a new architecture for bandpass delta-sigma modulators (BP-ΔΣMs) featuring finite impulse response (FIR) filters in the feedback path. The effectiveness of FIR feedback in lowpass delta-sigma modulators (LP-ΔΣMs) has been well-established in improving loop-filter linearity and robustness to clock jitter. Building upon these findings, we explore the application of bandpass FIR filters in single-bit BP-ΔΣMs. By contrast to conventional BP-ΔΣMs, the proposed technique significantly reduces out-of-band quantization error contents in the feedback signal. This approach is applicable to both discrete-time and continuous-time implementations. Further, we show that performance does not improve by increasing the number of FIR taps beyond a certain point. However, we can enhance filtering performance by employing non-equal coefficients within the filter. To validate the efficacy of the presented approach, the paper includes electrical simulation of a 4th-order active-RC BP-ΔΣM.
Bandpass ΔΣ Modulators with FIR Feedback J. Gorji, S. Pavan and J.M. de la Rosa Journal Paper · IEEE International Symposium on Circuits and Systems ISCAS 2023 abstractdoi
This paper investigates finite impulse response (FIR) feedback in bandpass delta-sigma modulators (BP- ΔΣMs ). FIR feedback in lowpass delta-sigma modulators (LP- ΔΣMs ) improves loop filter linearity and reduces the sensitivity of the modulator to clock jitter. We show that similar benefits can be obtained in a BP- ΔΣM if the FIR filter in the feedback path is made a bandpass one 1 1 This work was supported in part by Grant PID2019-103876RB-I00, funded by MCIN/AEI/10.13039/501100011033, by the European Union ESF Investing in your future, and by ’’Junta de Andalucía’’ under Grant P20-00599 and in part by the Center of Excellence in RF, Analog and Mixed-Signal ICs (CERAMIC), IIT Madras..
