In the first part of this work, we present a wideband spectrum sensing receiver with high sensitivity, wide dynamic range, and low power overhead. Reconfigurability in multi-band radios requires environmental awareness, and spectrum sensing can be used for optimal channel selection and adaptive interference suppression. The 300MHz-700MHz spectrum sensing receiver uses subsampling downconversion and digital-analog hybrid correlation to achieve -104dBm sensitivity and 84dB dynamic range for a 6MHz channel while consuming only 28mW of power. In the second part of this work, we present a wideband time division duplex (TDD) front-end with an innovative transmit/receive (T/R) switching scheme. T/R switches conventionally are off-chip components, and existing integrated designs have been narrowband or high loss. We propose a wideband integrated T/R switching technique in which the PA is re-used as an LNA during receive mode, and we demonstrate this in a 20dBm polar transmitter that can be re-purposed into a 3.4GHz-5.4GHz LNA achieving -6.7dBm P1dB and 5.1dB NF. The two systems presented in this thesis contribute key innovations towards fundamental aspects of future reconfigurable radios - greater front-end integration, wideband transceiver design, and spectrum awareness.