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Two Operating Mode Filtering Device

IP.com Disclosure Number: IPCOM000089740D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Ballatore, D: AUTHOR

Abstract

Shown in Fig. 1A is a filtering circuit which can be switched between two modes: boost and flat.

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Two Operating Mode Filtering Device

Shown in Fig. 1A is a filtering circuit which can be switched between two modes: boost and flat.

In flat mode the characteristic of the filter is relatively flat, as shown by curve 1 in Fig. 1B, and in boost mode the characteristic is as shown by curve 2.

The filter comprises two cells I and II. The signal to be filtered is applied at the IN terminal of cell I. Each cell comprises an operational amplifier A and an impedance network. The filtered signal is provided at the OUT terminal.

Switch S allows the operating mode of the filter to be changed between boost and flat. The input of cell II is taken at node 3 of voltage divider RB1 and RB2, which allows the Q factor of the filter to be varied, without changing the gain G = Vout over Vin at the frequency fo.

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