Abstract
A technique is described for improving the selectivity of a low-sensitivity multi-loop negative feedback active network, which uses one operational amplifier. Voltage amplifiers with positive finite gain are introduced inside the various loops of the network. This simplifies quite considerably the network function and improves the selectivity for a given range of element values while not affecting the low sensitivity of the network. Also, additional low impedance outputs are available which for a particular input make the network suitable for the simultaneous realization of more than one function (with common poles but different zeros). Second and third-order networks are examined in detail and experimental results are given from their use in the realization of a band-pass and a low-pass filter.