US 6,924,660 B2 · Calibration methods and circuits for optimized on-die termination

Abstract

Described are on-die termination (ODT) systems and methods that facilitate high-speed communication between a driver die and a receiver die interconnected via one or more signal transmission lines. An ODT control system in accordance with one embodiment calibrates and maintains termination resistances and drive currents to produce optimal output swing voltages. Comparison circuitry employed to calibrate the reference resistance is also used to calibrate the drive current. Termination elements in some embodiments are divided into two adjustable resistive portions, both of which are designed to minimize capacitive loading. One portion is optimized to produce a relatively high range of adjustment, while the other is optimized for fine-tuning and glitch-free switching.

Claims32

Dependent claims

A circuit comprising:

a. a first reference voltage node adapted to provide a first reference voltage;
b. a reference resistor having:
i. a first reference-resistor terminal coupled to the first reference voltage node;
and
ii. a second reference-resistor terminal;
c. a second reference voltage node adapted to provide a second reference voltage;
d. an on-die termination (ODT) resistor having:
i. a first ODT-resistor terminal;
and
ii. a second ODT-resistor terminal;
e. a multiplexer having:
i. a first multiplexer input terminal coupled to the second reference voltage node;
ii. a second multiplexer input terminal coupled to the second ODT-resistor terminal;
and
iii. a multiplexer output terminal;
and
f. a comparator having:
i. a first comparator input terminal coupled to the second reference-resistor terminal;
ii. a second comparator input terminal coupled to the multiplexer output terminal;
and
iii. a comparator output terminal.

18 more elements

Dependencies are inferred from the claim text.

Calibration methods and circuits for optimized on-die termination

Life of this patent

Calibration methods and circuits for optimized on-die termination

Life of this patent

Abstract

Claims32