Parasitic aware impedance matching techniques for RF amplifiers

This paper analyzes the impact of non-idealities of the lumped passive elements (inductor and capacitor) in the matching networks of RF amplifiers. This work infers that the representation of performance matrices of a matching network like sensitivity and harmonic rejection; in terms of input reflection coefficient (S11) is more convenient than the transfer functions. Expression of S11 of widely used L-, π- and T-networks have been derived as a function of inductor quality factor (QL), capacitor quality factor (QC) and transformation ratio. This formulation shows that the matching performance degrades severely due to component non-idealities. To circumvent this degradation, a modified set of design equations have been proposed for the L-network and the same has been extended for π- and T-network. Simulation results show that network synthesized on the basis of proposed set of equations nullify the effect of non-idealities by 70–80% in L-network and 10–20% in π-network but minor improvement in T-network.