High-order Pulse-Amplitude Modulation (PAM) provides the possibility to enhance the overall data rate in a serial data communication system while keeping the symbol rate low. The tight trade-offs between Signal-to-Noise Ratio (SNR) and sensitivity to Inter-Symbol-Interference (ISI), however, put some limitations on the order of PAM, depending on channel response. This article presents a methodological approach, in which different design aspects affecting link budget, such as noise, jitter, and quantization noise, will be studied. A similar procedure, is suggested to be implemented to find the optimal PAM order for different channel responses. Alternatively, this article suggests using a flexible serial data transceiver that can adapt different parameters, including PAM order, depending on channel response and target data rate.