How is intermodulation distortion measured?
Fundamentally, IMD describes the ratio (in dB) between the power of fundamental tones and third-order distortion products. IMD measurement starts with injecting a two-tone signal into a device under test (DUT). As an example, we’ll consider the behavior of an RF power amplifier.
What is meant by intermodulation distortion?
Intermodulation Distortion (IMD): When two signals mix in non-linear circuits or devices, new frequency components are created that are not in the original signal. The resulting signal error is called intermodulation distortion, or IMD. Synonyms.
What is third-order intermodulation distortion?
Two-tone third-order intermodulation distortion (IMD3) is the measure of the third-order distortion products produced by a nonlinear device when two tones that are close in frequency are received at its input.
What is a 2 tone signal?
Two-tone testing is a means of testing electronic components and systems, particularly radio systems, for intermodulation distortion. It consists of simultaneously injecting two sinusoidal signals of different frequencies (tones) into the component or system.
What is intermodulation noise?
Filters. Noise that is the result of modulation, demodulation, and any nonlinear characteristics of the transmission medium or transmission system components. See also modulation and noise.
How do you reduce intermodulation noise?
Prevent Intermodulation Noise
- Reduce the number of non-linear devices such as diodes, amplifiers in transmitters, and receivers.
- Operate the amplifiers in the linear range.
- Avoid poorly designed and low-quality components in the circuit, as the design and quality of circuit components can affect intermodulation noise.
What do you mean by two-tone modulation?
[′tü ¦tōn ‚mäj·ə′lā·shən] (communications) In teletypewriter operation, a method of modulation in which two different carrier frequencies are employed for the two signaling conditions; the transition from one frequency to the other is abrupt, with resultant phase discontinuities.
How to calculate the frequency of two tone intermodulation?
The frequencies of the two-tone intermodulation products can be computed by the equation: Where M & N are integers (can be positive or negative). The order of the distortion product is given by the sum of M + N. The second order intermodulation products of two signals at f
What is intermodulation distortion ( IMD ) and how is it defined?
2 What is Intermodulation Distortion (IMD) Harmonic distortion can be defined as a single-tone distortion product caused by device non-linearity. When a non-linear device is stimulated by a signal at frequency f1, spurious output signals can be generated at the harmonic frequencies 2f1, 3f1, 4f1,..Nf1.
How are distortions measured in intermodulation signal generator?
To measure intermodulation distortion, a signal generator is employed to generate the test signal with sufficiently low distortions. The generated signal is used as the stimulus to the Device Under Test (DUT). Meanwhile, the response from the DUT is sampled and then analyzed using Fast Fourier Transform (FFT).
Which is the most critical intermodulation distortion product?
The most critical intermodulation distortion product is the Third Order Intermodulation (TOI) product. It is generated when two signals are applied to a nonlinear device. The TOI products are usually within or close to the use-band, i.e. it can hit a neighboring channel in a communication system.