Noise behavior of microwave amplifiers operating under nonlinear conditions

Behavioral Modeling of Microwave Amplifiers Including Large-signal and Noise Interaction

“…A coupler is used to add the amplified noise and the pump signal delivered by a RF synthesizer. This solution is better than the one using a 3-dB combiner as depicted in [11,12] since the noise at the output of the coupler is slightly attenuated. A 20 dB attenuator is placed after the DUT in order to attenuate the signal at the input of the spectrum analyzer.…”

“…The variance of the noise a, which is equal to BN is negligible when its value is compared to as2. It has also been demonstrated in [11] that the components R 2(r), Rn3(r) and Rn4(r) which normally appear in the expression of (3) produce negligible values in the output noise PSD. The single-sided band (SSB) PSD of the output signal y(t) is then obtained by taking the Fourier transform of the autocorrelation function given by (3).…”

“…This kind of model has been also used to investigate the definition of the noise figure [9] or distortion and noise figure [10] in nonlinear devices. Recently, the noise behavior of several microwave amplifiers operating under large-signal conditions has been investigated with the help of a simple polynomial model and a dedicated experimental setup [11]. The comparison between theoretical and measured noise powers at the output of microwave devices has been performed at one frequency point and using a third-degree polynomial model.…”

“…Several improvements have been performed from our previous paper [11]. The degree of the polynomial has been increased and the experimental setup has been modified.…”

“…The autocorrelation function Ry(z) can be calculated, using the following formula: (2) where E[] denotes the expected value for a determinist process or the statistical average for a random process. The details concerning the derivation of (2) can be found in [11] and the following expression can be obtained:…”