# US 7,609,776 B2 · Quadrature frequency changer, tuner and modulator

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- Number: US 7,609,776 B2
- Document ID: US7609776B2
- Status: Granted
- Kind: B2
- Application number: 11/464,596
- Filed: 2006-08-15
- Published: 2007-02-22
- Granted: 2009-10-27
- Earliest claimed: 2005-08-16
- Assignees: Intel Corporation
- Inventors: Isaac Ali; Nicholas Paul Cowley
- Web page: https://patentgrep.com/patent/US7609776B2

## CPC

- H03D 3/009: {Compensating quadrature phase or amplitude imbalances}
- H03D: DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER (masers, lasers H01S; circuits capable of acting both as modulator and demodulator H03C; details applicable to both modulators and frequency-changers H03C; demodulating pulses H03K9/00; transforming types of pulse modulation H03K11/00; coding, decoding or code conversion, in general H03M; repeater stations H04B7/14; demodulators adapted for AC systems of digital information transmission H04L27/00; synchronous demodulators adapted for colour television H04N9/66)

## Abstract

A quadrature frequency changer comprising first and second mixers and a local oscillator and a tuner and modulator including the quadrature frequency changer are provided. The local oscillator provides first and second commutating signals which are nominally in phase-quadrature and includes an arrangement for changing the phase of the first commutating signal by 180° to provide a third commutating signal. The first mixer comprises first and second mixing stages for mixing an input signal with the first and second commutating signals and a summer for summing the mixer stage output signals. The second mixer comprises third and fourth mixing stages for mixing the same or a different input signal with the second and third commuting signals and a summer for summing the third and fourth mixer stage output signals.

## Claims

### Claim 1

A quadrature frequency changer comprising:
first and second mixers; and
a local oscillator, said local oscillator being arranged to provide first and second commutating signals which are nominally in phase-quadrature and including an arrangement for changing a phase of said first commutating signal by 180° to provide a third commutating signal, said first mixer comprising first and second mixing stages for mixing a first input signal with said first and second commutating signals, respectively, and a first linear combiner for forming a linear combination of output signals of said first and second mixing stages, said second mixer comprising third and fourth mixing stages for mixing a second input signal with said second and third commutating signals, respectively, and a second linear combiner for forming a linear combination of output signals of said third and fourth mixing stages.

### Claim 2 (depends on 1)

The frequency changer of claim 1, wherein said first to fourth mixing stages comprise the same circuitry.

### Claim 3 (depends on 1)

The frequency changer of claim 1, wherein each of said first to fourth mixing stages comprises a Gilbert cell.

### Claim 4 (depends on 1)

The frequency changer of claim 1, wherein each of said first and second combiners comprises a summer.

### Claim 5 (depends on 1)

The frequency changer of claim 1, wherein said local oscillator is a variable frequency local oscillator.

### Claim 6 (depends on 1)

The frequency changer of claim 1, wherein said first and second signals are connected together.

### Claim 7 (depends on 1)

The frequency changer of claim 1, wherein said phase changing arrangement is arranged to invert said phase of said first commutating signal to provide said third commutating signal.

### Claim 8 (depends on 7)

The frequency changer of claim 7, wherein said first commutating signal is a differential signal and said first and fourth mixing stages have differential inputs connected in anti-phase to receive said first commutating signal to form said phase changing arrangement.

### Claim 9

A tuner including a quadrature frequency changer comprising first and second mixers and a local oscillator, said local oscillator being arranged to provide first and second commutating signals which are nominally in phase-quadrature and including an arrangement for changing a phase of said first commutating signal by 180° to provide a third commutating signal, said first mixer comprising first and second mixing stages for mixing a first input signal with said first and second commutating signals, respectively, and a first linear combiner for forming a linear combination of output signals of said first and second mixing stages, said second mixer comprising third and fourth mixing stages for mixing a second input signal with said second and third commutating signals, respectively, and a second linear combiner for forming a linear combination of output signals of said third and fourth mixing stages.

### Claim 10

A modulator including a quadrature frequency changer comprising first and second mixers and a local oscillator, said local oscillator being arranged to provide first and second commutating signals which are nominally in phase-quadrature and including an arrangement for changing a phase of said first commutating signal by 180° to provide a third commutating signal, said first mixer comprising first and second mixing stages for mixing a first input signal with said first and second commutating signals, respectively, and a first linear combiner for forming a linear combination of output signals of said first and second mixing stages, said second mixer comprising third and fourth mixing stages for mixing a second input signal with said second and third commutating signals, respectively, and a second linear combiner for forming a linear combination of output signals of said third and fourth mixing stages.