# US 10,484,214 B2 · Technique for crosstalk reduction

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- Number: US 10,484,214 B2
- Document ID: US10484214B2
- Status: Granted
- Kind: B2
- Application number: 15/892,002
- Filed: 2018-02-08
- Published: 2018-06-28
- Granted: 2019-11-19
- Earliest claimed: 2011-11-30
- Assignees: Telefonaktiebolaget LM Ericsson (publ)
- Applicants: Telefonaktiebolaget Lm Ericsson (Publ)
- Inventors: Fenghao Mu; Lars Sundström
- Web page: https://patentgrep.com/patent/US10484214B2

## CPC

- H04L 25/08: Modifications for reducing interference; Modifications for reducing effects due to line faults {; Receiver end arrangements for detecting or overcoming line faults}
- H04B 3/32: Reducing cross-talk, e.g. by compensating
- H04B 15/04: the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver or in a tape-recorder
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04B: TRANSMISSION

## Abstract

A technique for cancelling or reducing crosstalk signals between controlled oscillators in an integrated circuit is provided. The technique involves an arrangement adapted to reduce a crosstalk signal generated by a first controlled oscillator to a second oscillator both comprised in the integrated circuit, wherein both controlled oscillators are configured to output a respective clock signal. The arrangement comprises a detector adapted to detect the crosstalk signal generated by the first controlled oscillator to the second controlled oscillator, a crosstalk cancellation circuit adapted to generate a cancellation signal having an amplitude substantially the same as that of the crosstalk signal and a phase substantially opposite to that of the crosstalk signal, and a cancellation signal injector adapted to introduce the cancellation signal into the second controlled oscillator.

## Claims

### Claim 1

A radio communication device comprising a crosstalk detector for use in an arrangement for reducing crosstalk between a first controlled oscillator (CO1) and a second controlled oscillator (CO2), wherein the crosstalk detector is configured to detect a crosstalk signal generated by the first controlled oscillator to the second controlled oscillator, the crosstalk detector comprising:
means for producing a mixed signal (m1(t)) by mixing a clock signal (S1(t)) generated by the second controlled oscillator with a signal having a fixed relationship with the clock signal;
means for filtering the mixed signal (m1(t)) to produce a filtered signal;
an amplifier configured to receive the mixed signal (m1(t)) and to produce an amplified signal (a1(t));
means for converting the amplified signal (a1(t)) into a signal (m2(t)) which is an indication for the crosstalk signal.

### Claim 2 (depends on 1)

The radio communication device of claim 1, wherein
the means for producing the mixed signal comprises a limiter and a mixer; and
the means for filtering comprises a band-pass filter.

### Claim 3 (depends on 1)

The radio communication device of claim 1, wherein
the means for converting the amplified signal (a1(t)) into the signal (m2(t)) comprises a rectifier that receives as input the amplified signal and outputs the signal (m2(t)).

### Claim 4 (depends on 3)

The radio communication device of claim 3, further comprising filtering means for filtering the signal (m2(t)).

### Claim 5 (depends on 3)

The radio communication device of claim 3, wherein the filtering means comprises a low-pass filter and an amplifier.

### Claim 6 (depends on 1)

The radio communication device of claim 1, wherein the means for converting the amplified signal (a1(t)) into the signal (m2(t)) comprises:
a first quadrature mixer;
a second quadrature mixer; and
an adder for adding the outputs of the first and second quadrature mixers.

### Claim 7 (depends on 1)

The radio communication device of claim 1, wherein the means for converting the amplified signal (a1(t)) into the signal (m2(t)) comprises:
a first quadrature mixer;
a second quadrature mixer; and
a multiplexor for multiplexing the outputs of the first and second quadrature mixers.

### Claim 8

A radio communication device, comprising:
an integrated circuit having a first controlled oscillator and a second controlled oscillator; and
an arrangement for reducing a crosstalk signal generated by the first controlled oscillator to the second controlled oscillator, the arrangement comprising:
a first crosstalk detector adapted to detect the crosstalk signal generated by the first controlled oscillator (CO) to the second controlled oscillator (CO);
a first crosstalk cancellation circuit adapted to generate a cancellation signal having an amplitude substantially the same as that of the crosstalk signal and a phase substantially opposite to that of the crosstalk signal; and
a first cancellation signal injector adapted to introduce the cancellation signal into the second CO, wherein
the first crosstalk detector comprises:
a mixer stage adapted to produce a mixed signal (m1(t)) by mixing a clock signal (S1(t)) generated by the second CO with a signal having a fixed relationship with the clock signal (S1(t)) generated by the second CO;
a filter adapted to filter the mixed signal (m1(t)) to produce a filtered signal;
a signal converter adapted to down-convert the filtered signal into a signal (m2(t)) which is an indication for the crosstalk signal.