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Nt1210 Lab Report

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The \gls{IP3} is defined as the point at which the output power curves of the fundamental frequency and of the third-order intermodulation product would intercept if they were linear, i.e, when the amplitude of the fundamental frequency would be equal to the amplitude of the third-order inter-modulation product. A practical rule that is employed in most radio frequency amplifiers is that the 1 dB compression point falls approximately 10 dB below the intercept point. The specification of IP3 is usually input-referred (IIP3), but can also be output-referred (OIP3) \cite{bastos}. In the small signals equivalent circuit, all of the \gls{DC} power supplies and bias voltages (V\textsubscript{Bias}) are short-circuited, like V\textsubscript{DD} …show more content…

Using the analysis of small signals, V\textsubscript{GS} = V\textsubscript{in} and therefore the circuit of the voltage gain A\textsubscript{V} is given by the expression: The input impedance of this circuit is given by $r_{in}= V_{in}/I_{in}= \infty$, since the gate of a transistor NMOS is an open-circuit. The output impedance is given by $r_{out}= V_{out}/I_{out}= r_{ds}\parallel r_{out}$, which is quite high, since it can range from some tens of k\ohm, to a few hundred k\ohm, depending on the current I\textsubscript{D} in the operation point. The output impedance can be calculated by applying a voltage source of value V\textsubscript{out}, and providing a current I\textsubscript{out} to the circuit and short-circuiting the input source, V\textsubscript{in} \cite{j.pao}. One of the most common ways to parametrize a circuit is by using the equivalent model of the transistor to the small signal analysis (used for low frequencies), or the S-parameters analysis, especially for RF circuits. However, these tests are only accurate enough for sizing linear devices, which is not the case of power amplifiers. Thus, it is necessary to resort to the analysis of large signals. For large signals, both the output and input impedances have to consider the values of frequency, DC voltage, output power, temperature, input power and

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