Book excerpt: Research in RFIC design has recently shifted towards direct conversion and subsampling architectures as an alternative to the conventional super-heterodyne architectures. Bandpass sampling architectures, also called subsampling architectures, exhibit several advantages over super-heterodyne architectures, notably, the complexity of subsampling architectures is significantly lower since no phase-locked loop is required. A direct consequence is that downconversion from RF to IF can be achieved with significant power savings as compared to the super-heterodyne architecture. Another significant benefit of such architectures is the capability for processing multiple signals in parallel. The ability to simultaneously handle multiple carriers makes subsampling architectures particularly well suited for GNSS applications, as downconversion of multiple frequency bands is required in GNSS environments. With the advent of the new civilian GPS signals, L2C and L5, and the onset of the new Galileo signal, a receiver that can process multiple signals without adding complexity, is highly desired. An integrated proof-of-concept subsampling GPS receiver front-end in 130 nm BiCMOS is presented in this dissertation. The receiver achieves a noise figure of less than 3.8 dB, the lowest ever recorded noise figure of a subsampling based receiver.