Changes

Before designing the matching networks, first you have to perform a stability analysis of the RF BFG193 transistor at the operating frequency of 1GHz. The table below gives the S-parameter values of this BJT at 1GHz:

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To perform a K-Δ stability test of the BJT, we need to calculate the following quantities:

<math> \left| \Delta \right| = \left| s_{11}s_{22} - s_{12}s_{21} \right| = \left| 0.1346 - j0.2539 \right| = 0.2873 </math>

<math> K = \frac {1 - |s_{11}|^2 - |s_{22}|^2 + |\Delta |^2 } { 2|s_{12}s_{21}| } = 1.0144 </math>

It can be seen that Rollet's condition, K > 1 and |&Delta;| <1, is satisfied at 1GHz. So the BFG193 BJT is unconditionally stable at 1GHz with a DC operating condition of V_CE = 10V and I_C = 10mA.

Although the BJT is not unilateral (s₁₂ &ne; 0), you will adopt a unilateral design strategy and will verify your design outcome later. For this purpose, you will set

<math> \Gamma_S = s_{11}^\ast = -0.4348 -j 0.1044 = 0.4472 \angle -166.5^o </math>

<math> \Gamma_L = s_{22}^\ast = 0.1408 + j0.2169 = 0.2586 \angle 57.0^o </math>

where &Gamma;_S and &Gamma;_L are the source and load reflection coefficients looking to the left and right of the transistor.

== Designing Input and Output Matching Networks ==