Societe Pour L'etude Et La Fabrication De Circuits Integres Speciaux

Societe Pour L'etude Et La Fabrication De Circuites Integres Speciaux

Boris Sokoloff

The symmetrical integrator comprises an operational amplifier having two floating inputs and two floating outputs each having a feedback connection to an input via a capacitor. An input capacitor is connected via two MOS transistors to two differential inputs of the integrator or via two additional MOS transistors to the inputs of the operational amplifier. The transfer function of the circuit is a pure integral or a sum of integrals if several input signals are applied to similar pairs of inputs. The integrator permits realization of filters whose transfer function has transmission zeros by utilizing additional inputs together with a direct capacitive coupling.

Symmetrical integrator and application of said integrator to an electric

A circuit having an inductive characteristic for the realization of filters in integrated circuits is constructed solely from switched capacitors and an operational amplifier. The circuit is provided between a first and a second terminal with a first capacitor in series with at least one switch. The switch is capable either of connecting the first capacitor between said two terminals or of isolating said capacitor from the first terminal. The circuit further comprises an operational amplifier having a feedback path between its output and its input via a second capacitor, and additional switches for transferring charges from the input of the circuit to the first capacitor and then from the first capacitor to the second capacitor, then again from the second capacitor to the first capacitor. Under these conditions, the circuit exhibits the characteristics of an inductance.

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Grenoble, France

Boris Sokoloff