Analog circuits component diagnosis is a challengingtask requiring expensive resources. This paper presents a lowcost method to identify deviations in multiple component valuesusing a precharacterisation of the impact of the deviations onthe digital signatures for a set of input excitations. The methodpredicts several circuit under diagnosis (CUD) deviations bymapping them to a scalar value that indicates the discrepancyof the defective and golden digital signatures. Input excitationconsists of a small set of sinusoidal signals with differentfrequencies. A digital signature is generated for every excitationset and compared to the golden response. The scalar discrepancyvalues are used to obtain the component deviations of the CUD.In order to generate the signatures, a CMOS monitor circuithas been designed and fabricated. The method is applied tothe identification of capacitance deviations in a Biquad filter.Simulated results show the possibilities of the proposal