Johnny Holmberg Lennart Harnefors Svante Signell A comparison of quantization noise levels of LDI and wave digital circulator allpass filters. 327-330 1999 conf/iscas/1999 ISCAS (3) http://doi.ieeecomputersociety.org/10.1109/ISCAS.1999.778851 db/conf/iscas/iscas1999-3.html#HolmbergHS99