Redriver with Output Receiver Detection that Mirrors Detected Termination on Output to Input
First Claim
1. A redriver device comprising:
- a differential input including a true differential input and a complement differential input, the true and complement differential inputs being driven to opposite states by a remote transmitter transmitting data;
a differential output including a true differential output and a complement differential output, the true and complement differential outputs being driven to opposite states by the redriver device when re-transmitting data to a remote receiver;
a differential redriving circuit, coupled to the differential input, for re-driving data sent by the remote transmitter onto the differential output as re-transmitted data; and
an output detector, coupled to the differential output, for detecting a far-end termination on the remote receiver and activating a detect signal in response to detection of the far-end termination,whereby the far-end termination on the remote receiver is detected the redriver device.
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Accused Products
Abstract
A redriver chip is inserted between a transmitter chip and a receiver chip and re-drives differential signals from the transmitter chip to the receiver chip. The redriver chip has switched output termination that switches to a high value to detect far-end termination at the receiver chip, and to a low value for signaling. An output detector detects when the receiver chip has termination to ground and enables switched input termination to provide termination to ground on the lines back to the transmitter chip so that the far-end termination on the receiver chip is mirrored back to the transmitter chip, hiding the redriver chip. An input signal detector detects when the transmitter chip begins signaling and enables an equalizer, limiter, pre-driver, and output stage to re-drive the signals to the receiver chip. The input signal detector also causes the switched output termination to switch to the low value termination for signaling.
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Citations
20 Claims
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1. A redriver device comprising:
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a differential input including a true differential input and a complement differential input, the true and complement differential inputs being driven to opposite states by a remote transmitter transmitting data; a differential output including a true differential output and a complement differential output, the true and complement differential outputs being driven to opposite states by the redriver device when re-transmitting data to a remote receiver; a differential redriving circuit, coupled to the differential input, for re-driving data sent by the remote transmitter onto the differential output as re-transmitted data; and an output detector, coupled to the differential output, for detecting a far-end termination on the remote receiver and activating a detect signal in response to detection of the far-end termination, whereby the far-end termination on the remote receiver is detected the redriver device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for mirroring detected far-end termination on a receiver to an input connected to a transmitter comprising:
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disconnecting an input termination resistance from an input to a redriver chip inserted between the transmitter and the receiver to set an input impedance of the input to a high-impedance state; disconnecting a first output termination resistance and a second output termination resistance from an output to the redriver chip inserted between the transmitter and the receiver to set an output impedance of the output to the high-impedance state; connecting the first output termination resistance to the output to set the output impedance to a first low-impedance state; waiting for a period of time to elapse after connecting the first output termination resistance to the output; sensing the output to detect when a far-end termination is connected to the receiver and activating a detect signal when detected; and when the detect signal is activated, connecting the input termination resistance to the input to mirror the far-end termination on the receiver to be visible to the transmitter; wherein the input impedance is set to a low-impedance state to mirror the far-end termination on the receiver for signaling. - View Dependent Claims (14, 15, 16, 17)
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18. A differential redriver comprising:
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a differential input having a true input line and a complement input line that are driven in opposite directions by a remote transmitter; a differential output having a true output line and a complement output line; wherein the true output line is coupled to a true input of a remote receiver through a true coupling capacitor; wherein the complement output line is coupled to a complement input of the remote receiver through a complement coupling capacitor; an equalizer that shapes a waveform of data received over the differential input to generate equalized data; a pre-driver that receives the equalized data from the equalizer and generates buffered data; an output stage that receives the buffered data from the pre-driver and drives current onto the true output line and onto the complement output line; output sensing means for sensing the differential output to detect when a far-end termination is connected to the remote receiver and for activating a detect signal when detected; a true input resistor for selectively mirroring the far-end termination back to the remote transmitter; a complement input resistor for selectively mirroring the far-end termination back to the remote transmitter; a true input transistor connected in series with the true input resistor between the true input line and a ground, wherein a gate of the true input transistor is controlled by the detect signal; and a complement input transistor connected in series with the complement input resistor between the complement input line and a ground, wherein a gate of the complement input transistor is controlled by the detect signal; whereby when the detect signal is activated, input termination is connected to the differential input to mirror the far-end termination on the remote receiver to be visible to the remote transmitter. - View Dependent Claims (19, 20)
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Specification