Monolithic tunable notch filter

A MONOLITHIC SECOND-ORDER state variable filter has been realized using a standard bipolar technology. It is a continuous time filter configured to provide notch, bandpass and lowpass functions, and is tuneable over three decades of frequency by the ratio of two external dc voltages. It has a 90dB dynamic range,>4OdB power supply rejection, a response with a notch depth >50dB, and temperature drift of E200ppm. It does not require the clock input of the switched-capacitor filters¿¿, or accurate passive components of RC active filters. It can serve as standalone filter.

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