Patent ID: 6359503
Filing Date: 2002-03-19
Classification: H02P,H03H

Abstract:
A cell structure for analog filters comprising:a differential amplifier stage inserted between a first reference supply voltage and a second reference voltage, said amplifier stage having at least one input terminal and at least one output terminal; wherein said amplifier stage comprises a pair of structurally identical half-cells, each provided with a transconductance amplifier stage and each having a differential output terminal connected through a respective capacitor to a common circuit node, each half cell comprising: a first transistor having a control terminal coupled to a differential input terminal of the amplifier stage, a first conduction terminal coupled to a high reference voltage source and a second conduction terminal, the first conduction terminal being unconnected to the other half cell; a second transistor having a control terminal, a first conduction terminal coupled thereto so as to form a diode-connected transistor, and a second conduction terminal coupled to the second conduction terminal of the first transistor, the output terminal appearing at the first conduction terminal of the second transistor; a first current source providing a current to the first conduction terminal of the second transistor; and a second current source sinking a current from the second terminal of the first and second transistors.