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 current domain while the output needs to be a voltage. 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 authors' knowledge, no one has previously reported single amplifier bi-quadratic active-RC topologies in fully differential transimpedance configuration.