Universal active filter

US5317217A · kind A · utility

Assignee

• Deutsche Thomson-Brandt GmbH · DE

Inventors

• Martin Rieger · Rottweil, DE
• Sabine Roth · Berlin, DE

Key dates

• Filing date: May 27, 1993
• Grant date: May 31, 1994
• Expiry date: May 27, 2013

Classification

• Technology area (CPC H): Electricity
• CPC primary: H03H11/0466
• WIPO field: Basic communication processes
• WIPO sector: Electrical engineering

Abstract

A universal filter is provided with three inputs Vh, Vb and V1, with one output Vout, with two transconductance amplifiers Gm1, Gm2, with four capacitors mCO, (1-m)CO, CO and LCO and an amplifier K as well as a voltage follower VF. Depending on the connections of the three inputs, the universal filter takes the form of a high-pass or low-pass or band-pass filter or a trap filter or an all-pass or an otherwise active filter. Advantageously, by selection of parameters (e.g., trans-conductance, gain, scaling), the various filter characteristics like quality (Q), slope, median frequency, amplification, etc., may be adjusted. A further advantage is that the low component count of the filter provides improved reliability, reduced cost and facilitates efficient and economic fabrication in discrete or integrated circuit form.