This article presents the theory and implementation of a quadrature and differential RF front-end receiver. Combining balun, low-noise amplifier (LNA), mixer, and oscillator in a single stage, the proposed circuit, named the Blixator, is well suited for low-power applications. The baseband's transimpedance amplifier (TIA) also shares part of its dc current with the Blixator cell, resulting in sub-milliwatt power consumption. To avoid additional power and area by quadrature LO generation, the I/Q signals are generated at RF, employing the inductors already required for providing the dc current path of the LNA transistors. The expressions for gain, noise figure (NF), and phase noise of the voltage-controlled oscillator (VCO) are derived, and the behavior of the circuit is thoroughly investigated. The prototype of the Blixator receiver is implemented in a 0.18-μm CMOS technology. The experimental results show a NF of 10.5 dB, an IIP3 of -15.5 dBm, at the maximum gain, and an image rejection of 23 dB, which meets the requirements for the Bluetooth Low Energy (BLE) standard. The circuit consumes only 340-μW, from a 0.8-V supply, and its die area is 0.75 mm2.