When on-wafer high frequency characterization of MOSFETs is performed, influences of the substrate coupling arising from metal bonding pads have to be considered in order to de-embed the characteristics of intrinsic transistors at high frequencies. In this work we examine different metal pad configurations used for the de-embedding procedure, i.e. pad compensation. Lumped circuit models are used to account for the effects of the metal pads and the substrate beneath. Good agreement is found between the Y-parameters of the proposed models and the measured data up to 18 GHz. With the guidance of the models we discuss designs of metal pad configurations, substrate resistivity, substrate isolation and layout of MOSFETs in order to improve the accuracy of the pad compensation.