Multi-tone ground truth estimation for ADC testing

During laboratory testing uncontrollable factors such as asynchronous clock, unknown path loss etc. can hamper the measurement process potentially leading to erroneous conclusions. In this paper we focus specifically on the problem of high speed ADC testing with one or more simultaneous sine wave input signals. Even a well constructed test environment can and will have difficulties in guaranteeing, with absolute certainly, the exact signal presented to the ADC's input, i.e. it can be difficult to know the ground truth input signal accurately.In this paper we present 3 new algorithm to assist in this task. The first two are extensions to previous works on ground truth estimation for a single tone and DC offset with and without complete knowledge of the tone's frequency respectively; we extend these works to cover multi-tone testing and introduce a very general and compact matrix formulation. The third algorithm extends this work again by considering the very common scenario where all the tones are frequency locked thereby reducing the size of the solution space and increasing accuracy of the ground truth estimation.