# US 12,224,748 B2 · Integrated circuit with configurable on-die termination

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,224,748 B2
- Document ID: US12224748B2
- Status: Granted
- Kind: B2
- Application number: 18/504,032
- Filed: 2023-11-07
- Published: 2024-05-02
- Granted: 2025-02-11
- Earliest claimed: 2005-12-19
- Assignees: Rambus Inc.
- Applicants: Rambus Inc.
- Inventors: Huy Nguyen
- Web page: https://patentgrep.com/patent/US12224748B2

## CPC

- H03K 19/0005: {Modifications of input or output impedance}
- H04B 1/0458: {Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages (matching circuits in general H03H)}
- H04L 25/0278: {Arrangements for impedance matching}
- H04L 25/0298: {Arrangement for terminating transmission lines}
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)
- H04B: TRANSMISSION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Described are integrated-circuit die with differential receivers, the inputs of which are coupled to external signal pads. Termination legs coupled to the signal pads support multiple termination topologies. These termination legs can support adjustable impedances, capacitances, or both, which may be controlled using an integrated memory.

## Claims

### Claim 1

An integrated-circuit die comprising:
a receiver having an input terminal and an output terminal;
a first switch having a first node coupled to a reference, a second node, and a third node, wherein the first switch selectively couples the first node to the third node and selectively couples the second node to the third node;
a first termination element coupled between the third node and the input terminal;
a second switch having a fourth node coupled to the reference, a fifth node, and a sixth node, wherein the second switch selectively couples the fourth node to the sixth node and selectively couples the fifth node to the sixth node; and
a second termination element coupled between the sixth node and the input terminal.

### Claim 2 (depends on 1)

The die of claim 1, wherein the first switch couples the first and third nodes and the second switch couples the fourth and sixth nodes in a serial termination configuration, and wherein the first switch couples the second and third nodes and the second switch couples the fifth and sixth nodes in a parallel termination configuration.

### Claim 3 (depends on 2)

The die of claim 2, wherein the first switch and the second switch include respective first and second control terminals.

### Claim 4 (depends on 3)

The die of claim 3, further comprising a register with an output port coupled to the first and second control terminals, the register to store a value that determines whether the first and second switches support the parallel termination configuration or the series termination configuration.

### Claim 5 (depends on 1)

The die of claim 1, further comprising a first reference-voltage node coupled to the second node and a second reference-voltage node coupled to the fifth node.

### Claim 6 (depends on 1)

The die of claim 1, further comprising a third switch and a capacitor coupled in parallel between the pad and the input terminal of the receiver.

### Claim 7

A communication system comprising:
a first IC die having:
an output pad; and
a transmitter coupled to the output pad to transmit data on the output pad;
a second IC die having:
an input pad; and
a receiver coupled to the input pad to receive the transmit data;
a communication channel extending between the output pad of the first IC die and the input pad of the second IC die; and
a termination circuit integrated with one of the first and second IC dies and coupled to a respective one of the output pad and the input pad, the termination circuit including:
a first switch having a first node coupled to a first reference, a second node, and a third node, wherein the first switch selectively couples the first node to the third node and selectively couples the second node to the third node;
a first termination element coupled between the third node and the input pad;
a second switch having a fourth node coupled to a second reference, a fifth node, and a sixth node, wherein the second switch selectively couples one of the fourth node to the sixth node and selectively couples the fifth nodes node to the sixth node; and
a second termination element coupled between the sixth node and the input pad.

### Claim 8 (depends on 7)

The communication system of claim 7, wherein the first switch couples the first and third nodes and the second switch couples the fourth and sixth nodes in a serial termination configuration, and wherein the first switch couples the second and third nodes and the second switch couples the fifth and sixth nodes in a parallel termination configuration.

### Claim 9 (depends on 8)

The communication system of claim 8, wherein the first and second switches include respective first and second control terminals.

### Claim 10 (depends on 9)

The communication system of claim 9, further comprising a register with an output port coupled to the first and second control terminals, the register to store a value that determines whether the first and second switches support a parallel termination configuration or a series termination configuration.

### Claim 11 (depends on 7)

The communication system of claim 7, further comprising a first reference-voltage node coupled to the second node and a second reference-voltage node coupled to the fifth node.

### Claim 12 (depends on 7)

The communication system of claim 7, further comprising a capacitor coupled between the first and second nodes.

### Claim 13

An integrated-circuit die comprising:
a pad to receive an input signal to the die;
a receiver having an input terminal coupled to the pad, a reference, and an output terminal;
a first switch having a first control terminal, a first node coupled to the reference, a second node, and a third node, wherein the first switch selectively couples the first node to the third node and selectively couples the second node to the third node;
a first termination element coupled between the third node and the input terminal;
a second switch having a second control terminal, a fourth node coupled to the reference, a fifth node, and a sixth node, wherein the second switch selectively couples the fourth node to the sixth node and selectively couples the fifth node to the sixth node;
a second termination element coupled between the sixth node and the input terminal; and
a register with an output port coupled to the first control terminal, the register to store a value that determines whether the first switch supports a parallel termination configuration or a series termination configuration.

### Claim 14 (depends on 13)

The integrated-circuit die of claim 13, wherein the register output port is coupled to the second control terminal and the value determines whether the second switch supports the parallel termination configuration or the series termination configuration.

### Claim 15 (depends on 13)

The integrated-circuit die of claim 13, wherein the first termination element includes a tunable capacitance.

### Claim 16 (depends on 15)

The integrated-circuit die of claim 15, wherein the output port of the register is coupled to the first termination element, and wherein the value selects from among a range of capacitances for the tunable capacitance.

### Claim 17 (depends on 13)

The integrated-circuit die of claim 13, wherein the register output port is coupled to the first termination element, and wherein the value determines a resistance of the termination element.

### Claim 18 (depends on 13)

The integrated-circuit die of claim 13, wherein the input terminal of the receiver is coupled to the pad via a third switch.

### Claim 19 (depends on 18)

The integrated-circuit die of claim 18, further comprising a capacitor coupled in parallel with the third switch.

### Claim 20 (depends on 18)

The integrated-circuit die of claim 18, wherein the capacitor is tunable over a range of capacitances.