A compact low-noise quadrature receiver for 24 GHz ISM applications in 0.13 mm CMOS technology is presented. The chip offers a conversion gain of 18 dB and a noise figure of 5 dB. The differential circuit consumes only 24 mW from a single 1.5 V supply. The low-noise amplifier, two mixers and on-chip quadrature generation are integrated on a minimal chip area of 0.48 mm 2 including pads.Introduction: The unlicensed industrial, scientific and medical (ISM) frequency band at 24 GHz gains growing attention for realisation of low-cost sensors for industrial, automotive or consumer applications. The constant demand for the lowest bill of materials requires system on a chip (SOC) solutions integrating analogue, digital and RF blocks. The promising high-frequency performance, high-level integration capability, along with inexpensive mask costs, make the standard 0.13 mm CMOS technology the optimal alternative for realisation of mass-market microwave sensors.Several publications report integrated receivers in CMOS consisting of a single low-noise amplifier (LNA) and a mixer [1, 2], while others concentrate on integration of complex large area phased arrays for wireless communications [3]. This Letter presents a quadrature receiver front-end in 0.13 mm CMOS optimised for a low noise performance at a lowest chip area. The circuit includes an LNA, two mixers and on-chip in-phase and quadrature (IQ) phase generation from an external local oscillator (LO) signal. The implementation of an IQ receive path provides unambiguous phase data, required for frequency-stepped continuous wave or for pulsed radar. The presented receiver is suitable for integration in radar sensors for automotive or industrial radar applications at the ISM band at 24 GHz.