Soft mute circuit
A soft mute circuit includes a programmable amplifier controlled by a register. Data is stored in the register from an adder that combines the current data in the register with a second number for increasing or decreasing the gain of the amplifier. A summation circuit includes a plurality of inputs coupled by gates to a summation node and the summation node is coupled to an input of the programmable amplifier. The gates are controlled by suitable logic for selecting input signals in any combination. A control loop maintains the gain of the amplifier at a predetermined level.
1. A circuit for unobtrusively masking transient signals in an electronic device by changing gain, said circuit comprising:
an amplifier having a first input for receiving control data and a second input for receiving a signal;
a register having an output coupled to said first input; and
an adder having an output coupled to said register for storing data in said register and having a pair of inputs, the output of said register also being coupled to one of said pair of inputs, the second of said pair of inputs being coupled to a source of slope data, said adder having a control input for adding or subtracting the slope data from the output of the register;
wherein said adder adjusts the gain of said amplifier in accordance with the slope data to change gain gradually.
2. The circuit as set forth in claim 1 and further including a control loop coupled to said adder for holding the gain of said amplifier at a predetermined value.
3. The circuit as set forth in claim 1 and further including a summation circuit coupled to said second input, wherein said summation circuit includes several inputs.
4. The circuit as set forth in claim 3 wherein said summation circuit further includes logic for selecting one, all, or combinations of signals from the several inputs for summation.
5. In a telephone, a soft mute circuit characterized by:
an amplifier having a first input for receiving control data and a second input for receiving a signal;
a register having an output coupled to said first input; and
an adder having an output coupled to said register for storing data in said register and having a pair of inputs, the output of said register also being coupled to one of said pair of inputs, the second of said pair of inputs being coupled to a source of slope data, said adder having a control input for adding or subtracting the slope data from the output of the register;
wherein said adder adjusts the gain of said amplifier in accordance with the slope data to mute or unmute gradually.
6. The telephone as set forth in claim 5 wherein said telephone includes a summation node and said summation node is coupled to said second input.
7. The telephone as set forth in claim 6 wherein telephone includes a plurality of band pass filters, each of said band pass filters having an output coupled to said summation node.