New topology for implementing bandpass, bandstop and allpass filters with CFAs

In this brief, a new filter topology based on current feedback amplifiers is presented and compared with its operational amplifier counterpart. The circuits arising from the new topology have the important advantage that access to the Z node of the current feedback amplifier is not required, as is the case with many existing current feedback amplifier filter circuits. The operation and requirements for each of the filters are described. Theoretical results and circuit limitations are discussed and verified with experimental results. In one experiment a bandpass filter with a calculated Q and centre frequency of 20 and 158.53 kHz, respectively was built using the OPA2607 dual CFAs IC. Measured results yielded a Q of 20.153 at a centre frequency of 148.62 kHz showing close agreement with theory.