# US 10,483,910 B2 · Multiport inductors for enhanced signal distribution

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- Number: US 10,483,910 B2
- Document ID: US10483910B2
- Status: Granted
- Kind: B2
- Application number: 15/423,398
- Filed: 2017-02-02
- Published: 2018-08-02
- Granted: 2019-11-19
- Earliest claimed: 2017-02-02
- Assignees: Credo Technology Group Limited
- Applicants: Credo Technology Group Limited
- Inventors: Xiang Gao
- Web page: https://patentgrep.com/patent/US10483910B2

## CPC

- H03B 5/1215: {the current source or degeneration circuit being in common to both transistors of the pair, e.g. a cross-coupled long-tailed pair}
- H01F 5/003: {Printed circuit coils}
- H01F 17/0006: {Printed inductances (printed coils for dynamo-electric machines H02K3/26; printed circuits H05K)}
- H03B 5/1228: {the amplifier comprising one or more field effect transistors}
- H10D 1/20: Inductors
- H01F 2005/043: {having multiple pin terminals, e.g. arranged in two parallel lines at both sides of the coil}
- H03B: GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS (generators adapted for electrophonic musical instruments G10H; masers or lasers H01S; generation of oscillations in plasma H05H)
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

Integrated circuits such as multi-channel transceivers may share oscillators having loop inductors. To minimize the driving distance from the shared oscillators to the transceiver modules, the loop inductor may be equipped with an additional sense port diametrically opposite to the drive port. An oscillator drive core may be coupled to the drive port to provide an oscillating signal at the drive and sense ports. The oscillating signals can be converted into digital clock signals by way of a differential amplifier. Three-loop inductor designs and/or multi-winding inductor designs may be preferred for minimizing parasitic effects of the added sense port.

## Claims

### Claim 1

An integrated circuit comprising:
a substrate; and
an inductor having:
multiple loops on said substrate, each loop defining a corresponding dipole, said dipoles summing to zero with two side loop dipoles being equal and arranged symmetrically relative to a center loop dipole;
a drive port on an outer perimeter of the inductor; and
a sense port connected to taps on the outer perimeter, the sense port positioned diametrically opposite the drive port.

### Claim 2 (depends on 1)

The circuit of claim 1, wherein the drive port also serves as an output port.

### Claim 3 (depends on 2)

The circuit of claim 2, further comprising an oscillator drive core coupled to the drive port to produce oscillating signals from the drive port and the sense port.

### Claim 4 (depends on 3)

The circuit of claim 3, wherein the oscillator drive core adjusts a frequency of the oscillating signals in response to a control signal.

### Claim 5 (depends on 1)

The circuit of claim 1, wherein the inductor includes multiple windings for each loop.

### Claim 6 (depends on 5)

The circuit of claim 5, wherein the inductor further includes a crossover on the outer perimeter closest to the sense port, and wherein the taps are connected on either side of the crossover.

### Claim 7 (depends on 1)

The circuit of claim 1, wherein the inductor is a single-winding, three-loop inductor.

### Claim 8 (depends on 7)

The circuit of claim 7, wherein a first of the sense port taps connects to the outer perimeter of a first of the two side loops at a point closest to a terminal of the sense port, and wherein a second of the sense port taps connects to the outer perimeter of a second of the two side loops at a point closest to a corresponding terminal of the sense port.

### Claim 9 (depends on 1)

The circuit of claim 1, wherein the inductor has only one winding, and wherein each tap connects to the outer perimeter at a point closest to a terminal of the sense terminal subject to obtaining a sense port signal amplitude at least 50% of a drive port signal amplitude.

### Claim 10

An electrical circuit manufactured on a substrate, the electrical circuit comprising:
at least two modules; and
a shared oscillator including:
an inductor having a drive port and a sense port, the inductor being a three-loop inductor with a center loop and two side loops, the two side loops having associated dipoles that combine to substantially cancel a dipole associated with the center loop; and
a drive core coupled to the drive port to produce oscillating signals from the drive port and the sense port,
wherein a first of the at least two modules receives a clock derived from the drive port's oscillating signal via a first trace, and a second of the at least two modules receives a clock derived from the sense port's oscillating signal via a second trace,
wherein the first and second traces, along with any inline buffers, have a combined length less than a shortest distance between the two modules.

### Claim 11 (depends on 10)

The circuit of claim 10, wherein the first and second modules each include a communications transmitter or a communications receiver.

### Claim 12 (depends on 10)

The circuit of claim 10, wherein the first and second modules are positioned on opposite sides of the shared oscillator.

### Claim 13 (depends on 10)

The circuit of claim 10, wherein the drive core adjusts a frequency of the oscillating signals in response to a control signal.

### Claim 14 (depends on 10)

The circuit of claim 10, wherein the inductor includes multiple windings for each loop, wherein the inductor further includes a crossover on the outer perimeter closest to the sense port, and wherein terminals for the sense port are connected on either side of the crossover.

### Claim 15 (depends on 10)

The circuit of claim 10, wherein the inductor is a single-winding inductor.

### Claim 16 (depends on 15)

The circuit of claim 15, wherein terminals for the sense port each connect to an outer perimeter of a corresponding one of the two side loops at a point closest to a respective terminal of the sense port.

### Claim 17

A method for manufacturing an integrated circuit with a shared on-chip oscillator, the method comprising:
providing an inductor having:
a center loop and two side loops on a substrate, the two side loops having associated dipoles that combine to substantially cancel a dipole associated with the center loop;
a drive port on an outer perimeter of the inductor; and
a sense port connected to taps on the outer perimeter, the sense port positioned diametrically opposite the drive port;
coupling a drive core to the drive port to produce oscillating signals from the drive port and the sense port;
providing a first trace to convey a clock derived from the drive port's oscillating signal to a first circuit module on one side of the inductor; and
providing a second trace to convey a clock derived from the sense port's oscillating signal to a second circuit module on an opposite side of the inductor, wherein the first and second traces have a combined length that is less than a shortest distance between the first and second circuit modules.

### Claim 18 (depends on 17)

The method of claim 17, further comprising providing a trace to supply a control signal to the drive core to adjust a frequency of the oscillating signals.

### Claim 19 (depends on 17)

The method of claim 17, wherein the inductor includes multiple windings for each loop, wherein the inductor further includes a crossover on the outer perimeter closest to the sense port, and wherein each terminal of the sensor port connects to an opposite side of the crossover from the other terminal of the sense port.

### Claim 20 (depends on 17)

The method of claim 17, wherein each terminal of the sense port connects to the outer perimeter of a corresponding side loop at a point closest to a respective terminal of the sense port.