US 12,652,075 B1Granted

Dual-mode receiver termination detection circuit

AssigneeCadence Design Systems, Inc.

InventorsSatya Someswara Kaushik Yanamandra, Emmanuel Hagan, James Dennis Vandersand, Jr.

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Abstract

Examples relate to a receiver termination detection circuit for wireline datalinks. A transmitter circuit includes positive and negative output nodes coupled through a channel to a receiver. A detection circuit comprises programmable pull-up and pull-down resistors coupled to the output nodes, and voltage comparators with independent reference voltage inputs. A mode selection input selects between single-ended and differential detection modes. Control logic drives the output nodes concurrently in single-ended mode and differentially in differential mode. The comparator outputs are sampled after a programmable time delay to detect receiver termination. The circuit supports both AC-coupled single-ended and DC-coupled differential termination detection while maintaining common-mode voltage during transitions to normal operation.

Claims20

Dependent claims

A device, comprising:

a transmitter circuit having positive and negative output nodes;
and
a receiver termination detection circuit to identify valid receiver termination of a data link, the receiver termination detection circuit comprising:
programmable resistors coupled to the positive and negative output nodes;
a first voltage comparator coupled to the positive output node and having a positive reference voltage input for comparison to a voltage of the positive output node;
a second voltage comparator coupled to the negative output node and having a negative reference voltage input, independent of the positive reference voltage input, for comparison to a voltage of the negative output node;
a mode selection input to select between a single-ended detection mode for identifying single-ended receiver termination and a differential detection mode for identifying differential receiver termination;
and
control logic coupled to the mode selection input and the first and second voltage comparators to:
in the single-ended detection mode, cause the positive and negative output nodes to be driven concurrently;
in the differential detection mode, cause the positive and negative output nodes to be driven differentially;
and
sample outputs of the voltage comparators after a programmable time delay to detect receiver termination of the data link.

10 more elements

Dependencies are inferred from the claim text.