This brief presents a fully integrated CMOS receiver that is capable of dual-mode frequency-modulated continuous-wave (FMCW) and ultrawideband (UWB) radar operations using the 0.13-mu m CMOS technology. The circuit consists of a low-noise amplifier, active mixers, an in-phase and quadrature generator, and buffers. In the proposed receiver, not only the gain but also the bandwidth of the overall receiver can be tailored by the switching of the center frequencies of stages and without lowering the quality factor of each stage. As a result, the receiver achieves a conversion gain of 36.7 dB, a 1-dB power gain compression point (P1dB) of -29.7 dBm, and a double sideband (DSB) noise figure (NF) of 6.1 dB in the narrowband FMCW mode. The receiver also achieves a conversion gain of 27.4 dB with a 3-dB bandwidth of 6.1 GHz, a P1dB of -21.6 dBm, and a DSB NF of 7.4 dB in the UWB pulse mode. Its performance is comparable with that of previously published chips that only operate in a single mode.