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I/Q Imbalance

Apply I/Q imbalances to complex signal

  • Library:
  • Communications Toolbox / RF Impairments

  • I/Q Imbalance block

Description

The I/Q Imbalance block applies in-phase and quadrature imbalances to a complex signal. This block applies an amplitude imbalance, a phase imbalance, and a DC offset to the in-phase and quadrature signal components. For more information, see I/Q Imbalance Implementation and Algorithms.

Ports

Input

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Complex signal, specified as a scalar or vector.

Data Types: double | single
Complex Number Support: Yes

Output

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Output signal, returned as a scalar or vector. This output is the same dimension and data type as the input signal.

Parameters

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I/Q amplitude imbalance in decibels of signal power, specified as a scalar. For more information, see Algorithms.

I/Q amplitude imbalance in degrees, specified as a scalar.

In-phase component DC offset, specified as a scalar.

Quadrature component DC offset, specified as a scalar.

Block Characteristics

Data Types

double | single

Multidimensional Signals

no

Variable-Size Signals

no

More About

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Algorithms

The I/Q amplitude imbalance, I/Q phase imbalance, and DC offset impairments are described sequentially in the section.

  1. For an I/Q amplitude imbalance, Ia, the impairment is applied to the input signal, xr+ jxi and y AmplitudeImbalance is an intermediate output.

    y AmplitudeImbalance y rAmplitudeImbalance + jyiAmplitudeImbalance

    y AmplitudeImbalance = (10(0.5Ia/20)xr)+j(10(0.5Ia/20)xi)

  2. For an I/Q phase imbalance, Ip, the impairment is applied to y AmplitudeImbalance and yPhaseImbalance is an intermediate output.

    yPhaseImbalance yrPhaseImbalance + jyiPhaseImbalance

    yPhaseImbalance =(e(j(0.5πIp180))yrAmplitudeImbalance)+(e(j(π2+0.5πIp180))yrAmplitudeImbalance)

  3. For DC offsets, IDC and QDC, the impairment is applied to y PhaseImbalance and y is the final output.

    y = (yrPhaseImbalance + IDC) + j(yiPhaseImbalance + QDC)

Variables for these calculations are defined in this list.

  • I a is the I/Q amplitude imbalance.

  • Ip is the I/Q phase imbalance.

  • IDC is the in-phase DC offset.

  • QDC is the quadrature DC offset.

  • x is the complex input signal and is given by xr + jxi.

    • xr and xi are the real and imaginary parts, respectively, of x.

  • y is the complex output signal and is given by yr + jyi.

    • yr and yi are the real and imaginary parts, respectively, of y.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Introduced before R2006a