A 5th-order delta-sigma modulator with single-opamp resonator

A new circuit configuration realizing 2
^nd
-order resonator with one operational amplifier is applied to a 5
^th
-order deltasigma (ΔΣ) modulator. The proposed resonator enables us to any kinds of 2
^nd
-order transfer function, which means that the resonator can realize a single feedback modulator with feed forward compensation[1,2]. Collaborating with other two improved features of a kickback relaxation filter and a simple resistor adder, we fabricated the highly efficient 5
^th
-order ΔΣ modulator with only three opamps, whose FOM was 0.24 pJ/conv.