Schematics and analysis
The OTA-C LP cell is a variant of this circuit.
Kirchoff in yields:
is simply grounded. The current at the output of the OTA is:
The op-amp is used as an (inverted) current to voltage converter:
Solving for and dividing by , we find the transfer function:
The pole is at the frequency such that:
Olivier Gillet: With +/-5V rails, Rb=10k, Rs=220, C=1nF, 1/2 TL072 for op-amp and LM13700, the OTA-C LP cell is unstable (crashes to one of the rails for signals peaking at more than 3.6V), but this configuration is not.