High order continuous time filter
AssigneeST-Ericsson SA
InventorsMatteo Conta, Andrea Baschirotto, Stefano D'Amico
Life of this patent
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Abstract
There is described a continuous time filter of at least a second (or higher) order, comprising one or more first order filter stages of a first type, the or each first order filter stage of the first type comprising a reactive component and an impedance dependent on the difference between the input and output voltages of the filter stage. The filter includes at least one first order filter stage of a second type, the or each second order filter of the second type comprising a reactive component and an impedance dependent on the sum of the input and output voltages of the filter stage. The filter includes a transfer function of the continuous time filter that is obtained comprising complex poles.
Claims14
A continuous time filter of at least a second (or higher) order, comprising:
- one or more first order filter stages of a first type, each first order filter stage of the first type comprising a reactive component and an impedance of a first type, the impedance of the first type being such that a first current therethrough is dependent on the difference between the input and output voltages of the filter stage;
- at least one first order filter stage of a second type, each first order filter stage of the second type comprising a reactive component and an impedance of a second type, the impedance of the second type being such that a second current therethrough is dependent on the sum of the input and output voltages of the filter stage, the impedance of the second type being realized by arranging a pair of transistors in cross-diode connection;
- wherein a transfer function of the continuous time filter is obtained comprising complex poles.
A continuous time filter of at least a second (or higher) order, comprising:
- one or more first order filter stages of a first type, each first order filter stage of the first type comprising a differential input and output, a reactive component and an impedance of a first type, the impedance of the first type being such that a first current therethrough is dependent on the difference between the input and output voltages of the filter stage;
- at least one first order filter stage of a second type, each first order filter stage of the second type comprising a differential input and output, a reactive component and an impedance of a second type, the impedance of the second type being such that a second current therethrough is dependent on the sum of the input and output voltages of the filter stage, the impedance of the second type being realized by arranging the second pair of transistors in cross-diode connection;
- wherein the differential inputs and outputs of the filter stages of the first and second types respectively comprise positive and negative inputs and positive and negative outputs, the filter stages of the first and second types being configured in a sequential ladder configuration such that the positive output node of one of the stages of the first or second types is arranged to provide a signal to the positive input node of a succeeding stage of the first or second types, and the negative output node of the one of the stages of the first or second types is arranged to provide a signal to the negative input node of the succeeding stage of the first and second types, wherein a transfer function of the continuous time filter is obtained comprising complex poles.
Dependencies are inferred from the claim text.