Insensitive voltage-mode and current-mode filters fromtransimpedance opamps

摘要

A commercially available transimpedance opamp, with compensationnpin (AD 844 or AD 846) is surely a right choice to implementnhigh-performance biquad in the current mode. Fabre's remarkable articlen[1993] richly deserves credit. Nevertheless the author contributes tonthe wider and more reasonable utilisation of those circuits, especiallynin cases where a conventional opamp is not suitable. Its parasiticninherent features are presented here in a more characteristic way. Thengoal of this work is not to criticise Fabre's paper, but to supplementnit, to make it more accurate and intelligible. First, from principles ofnmethodology the author recommends distinguishing more modes in which thengiven circuit can operate. These are especially applied basic modes,nnamely the classical voltage mode (VM) and the adjoint current moden(CM), when all subnetworks operate either with voltage or currentnsignals. However, if a certain subcircuit (usually an active element)noperates in a complementary mode (opposite to other parts) this isnconsidered as hybrid modes, namely the voltage-current mode (V/CM) ornthe current-voltage mode (C/VM), respectively. The conventional opampnoperates in VM whereas the current conveyor and transimpedance amplifiernoperate in CM