Multi-frequency and multi-constellation global navigation satellite system (GNSS) signals bring opportunities and challenges for GNSS data processing. Inter-frequency biases, including differential code biases (DCBs) and differential phase biases (DPBs), should be properly treated in GNSS data processing. DCBs and DPBs are stable over long periods, but their short-term variation characteristics are not clear. This study investigates the short-term temporal variations of DPBs derived from code and phase observations for GPS, BDS-2, BDS-3, and Galileo. The results show that receiver-related DPBs are closely associated with receiver type, signal frequency, and satellite system, and that the short-term variations of multi-constellation and multi-frequency DPBs should be considered when high-precision positioning and ambiguity resolution are performed.