This paper presents the trade-offs facing bandpass sampling receiver architectures for ultra-low power applications. To illustrate these trade-offs, three different bandpass sampling receiver architectures are specified for the Bluetooth low energy and 802.15.4 standards using a novel system design methodology which guarantees fast convergence to a non-over-designed solution. A wideband simulation tool validates and optimizes the block parameters. The three architectures are compared to find the critical blocks in power consumption related to each configuration, and therefore, the trade-offs between the blocks' specifications.