US 5,530,391 AGranted

Filter circuit with a resonator operated in series resonance

AssigneeTemic Telefunken microelectronic GmbH

InventorsRolf Bohme, Johann Burkhart, Johann Traub, Konrad Hirsch

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Abstract

A filter that has a resonator operated in series resonance and a two-pole terminal resonator circuit with a resonator whose electric conductance can be divided into a useful component and a parasitic component. A first differential stage actuated by a signal source and having two active elements whose ground connections are each linked to a respective current source and to a respective connection of the two-terminal resonator. A compensation circuit having two connections and which simulates the parasitic component of the resonator electric conductance is connected to a second differential stage which actuated by the signal source, is of the same type as the first differential stage, and has two active elements whose ground connections are each linked to a respective current source and to a respective connection of the compensation circuit. An evaluation circuit is linked to the two mutually reversed, i.e. connected in phase opposition, output connections of the two differential stages.

Claims19

Dependent claims

A filter circuit having a resonator operated in series resonance, comprising:

a) a two-terminal resonator circuit including a resonator (X.sub.R) whose electric conductance (L.sub.R) includes a useful component (L.sub.R) and a parasitic component (L.sub.P),
b) a first differential stage actuated by a signal source (S) and having two output connections and two active elements whose ground connections are respectively connected to ground via respective first current sources and to a respective terminal of said two-terminal resonator circuit,
c) a compensation circuit which has two connections and which simulates said parasitic component (L.sub.P) of said resonator electric conductance (L.sub.R),
d) a second differential stage actuated by said signal source (S) and of the same conductivity type as said first differential stage, and having two output connections and two active elements whose ground connection are respectively connected to ground via respective second current sources and to a respective connection of said compensation circuit,
e) means connecting said two output connections of said first differential stage in phase opposition with said two output connections of said second differential stage, and
f) an evaluation circuit connected to the two mutually connected output connections of said two differential stages for providing a load to said filter circuit.

3 more elements

Dependencies are inferred from the claim text.