Programmable echo cancellation filter
First Claim
1. A programmable echo cancellation filter for echo signal cancellation for a transceiver, said filter comprising:
- a signal output;
a signal input for receiving a transmission signal emitted by the transceiver;
an input resistor connected to the signal input;
an operational amplifier, having a signal input connected to the input resistor and having a signal output connected to an output resistor;
a first programmable resistor circuit provided between the signal output of the operational amplifier and the signal input of the operational amplifier;
a second programmable resistor circuit provided between the output resistor and the signal output;
a third programmable resistor circuit provided between the first programmable resistor circuit and the signal output;
the first, second, and third programmable resistor circuits each having a plurality of switching elements connected in parallel each switching element having a resistor and an associated controllable switch, each controllable switch having a first terminal connected to the resistor and a second terminal connected to a virtual reference voltage terminal.
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Accused Products
Abstract
Programmable echo cancellation filter for echo signal cancellation for a transceiver having a signal input (13) for receiving the transmission signal emitted by the transceiver (1), an input resistor (36) connected to the signal input (13), an operational amplifier (39), whose signal input (38) is connected to the input resistor (36) and whose signal output (41) is connected to an output resistor (43), a first programmable resistor circuit (48), which is provided between the signal output (41) of the operational amplifier (39) and the signal input (38) of the operational amplifier, a second programmable resistor circuit (51), which is provided between the output resistor (43) and a signal output (15) of the echo cancellation filter (14), a third programmable resistor circuit (55) which is provided between the first programmable resistor circuit (48) and the signal output (15) of the echo cancellation filter (14), the programmable resistor circuits (48, 51, 55) each having a plurality of resistors (65) which are terminated in parallel and are connected to a first terminal (68) of an associated controllable switch (66), the controllable switches (66) having a second terminal (69) connected to a virtual reference voltage terminal with a very low voltage swing.
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Citations
17 Claims
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1. A programmable echo cancellation filter for echo signal cancellation for a transceiver, said filter comprising:
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a signal output;
a signal input for receiving a transmission signal emitted by the transceiver;
an input resistor connected to the signal input;
an operational amplifier, having a signal input connected to the input resistor and having a signal output connected to an output resistor;
a first programmable resistor circuit provided between the signal output of the operational amplifier and the signal input of the operational amplifier;
a second programmable resistor circuit provided between the output resistor and the signal output;
a third programmable resistor circuit provided between the first programmable resistor circuit and the signal output;
the first, second, and third programmable resistor circuits each having a plurality of switching elements connected in parallel each switching element having a resistor and an associated controllable switch, each controllable switch having a first terminal connected to the resistor and a second terminal connected to a virtual reference voltage terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification