The commercial significance of ubiquitous chips, especially of radio frequency identification devices: (RFID), and the advantages compared to other identification technologies, for e.g. the barcode, has been discussed in several papers.. In order to achieve higher operational distances and to improve the operational reliability of passive RFID Tags, the design of integrated circuits with. ultra-low power consumption and novel concept,; for high-efficiency energy scavenging are. an emerging task. This article deals with general limitations and novel systematically design approaches concerning rectification circuits for ultra-low power levels at UHF (ultra high frequencies) and microwave frequencies. By using the presented characteristic parameters it is possible to optimize multi-stage. rectifiers at the ultra-low power domain and to verify the applicability of a given solid-state and assembly technology.