Single amplifier bi-quadratic filter topologies in transimpedance configuration

The authors propose two single amplifier low pass filter topologies achieving a second order roll-off in a transimpedance (i-to-v) configuration. Both topologies are derived with the constraint of fully differential signal processing. A transimpedance configuration finds direct application in scenarios when the input signal is in the current domain while the output needs to be a voltage. The output of a current steering digital-analog converter, and output of a down-conversion mixer, are two such examples. The transimpedance active-RC configurations presented here achieve the desired filtering with a single op-amp while eliminating redundant voltage conversion. Thus, immense advantages in terms of noise, linearity and area are obtained. To the best of the authors´ knowledge, no one has previously reported single amplifier bi-quadratic active-RC topologies in a fully differential transimpedance configuration.