Crosstalk reduction in multiplexers
First Claim
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1. A multiplexer, comprising:
- a plurality of multiplexer inputs, each of the multiplexer inputs being a differential input;
a multiplexer output, the multiplexer output being a differential output;
selection circuitry configured to enable an active signal path from a selected one of the multiplexer inputs to the multiplexer output, the selection circuitry also being configured to disable unselected signal paths corresponding to unselected ones of the multiplexer inputs; and
conversion circuitry comprising a plurality of analog amplifiers, each analog amplifier having a high input impedance and being configured to amplify a differential voltage between complementary signals of a corresponding one of the multiplexer inputs for a corresponding one of the unselected signal paths, the conversion circuitry being configured to use the amplified differential voltage to convert, for each of the unselected signal paths, a corresponding differential signal to a common mode signal,wherein the selection circuitry is configured to reject the common mode signal.
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Abstract
Multiplexers are described in which differential signals on the signal paths associated with unselected differential inputs are converted to common mode signals to reduce crosstalk between unselected signal paths and the multiplexer'"'"'s active signal path.
9 Citations
28 Claims
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1. A multiplexer, comprising:
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a plurality of multiplexer inputs, each of the multiplexer inputs being a differential input; a multiplexer output, the multiplexer output being a differential output; selection circuitry configured to enable an active signal path from a selected one of the multiplexer inputs to the multiplexer output, the selection circuitry also being configured to disable unselected signal paths corresponding to unselected ones of the multiplexer inputs; and conversion circuitry comprising a plurality of analog amplifiers, each analog amplifier having a high input impedance and being configured to amplify a differential voltage between complementary signals of a corresponding one of the multiplexer inputs for a corresponding one of the unselected signal paths, the conversion circuitry being configured to use the amplified differential voltage to convert, for each of the unselected signal paths, a corresponding differential signal to a common mode signal, wherein the selection circuitry is configured to reject the common mode signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A multiplexer, comprising:
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a plurality of multiplexer inputs, each of the multiplexer inputs being a differential input; a multiplexer output, the multiplexer output being a differential output; selection circuitry configured to enable an active signal path from a selected one of the multiplexer inputs to the multiplexer output, the selection circuitry also being configured to disable unselected signal paths corresponding to unselected ones of the multiplexer inputs; and a plurality of active devices, each of the active devices having a high input impedance and being configured to combine complementary signals on complementary circuit nodes of a corresponding one of the unselected signal paths resulting in a common mode signal, wherein the selection circuitry is configured to reject the common mode signal. - View Dependent Claims (13, 14, 15, 19, 20, 21, 22, 23)
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16. A multiplexer, comprising:
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a plurality of multiplexer inputs, each of the multiplexer inputs being a differential input and being configured to impedance match with terminating impedance circuitry; a multiplexer output, the multiplexer output being a differential output; selection circuitry configured to enable an active signal path from a selected one of the multiplexer inputs to the multiplexer output, the selection circuitry also being configured to disable unselected signal paths corresponding to unselected ones of the multiplexer inputs; a plurality of switches, each of the switches being configured to connect complementary circuit nodes of a corresponding one of the unselected signal paths resulting in a common mode signal; and a plurality of isolation circuits, each isolation circuit being associated with a corresponding one of the signal paths being configured to isolate the corresponding multiplexer input from the common mode signal, and including a plurality of transmission gates, wherein the selection circuitry is configured to reject the common mode signal. - View Dependent Claims (17, 18, 24, 25, 26, 27, 28)
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Specification