The demand for lower cost and form factor and increased re-configurability in wireless systems has driven the investigation of blocker-tolerant software-defined radios [1-4]. While promising, a reduction in system form-factor will result in lower isolation among antennas due to the co-existence of multiple ratios or lower isolation within duplexers for FDD systems due to their reduced size and/or increased re-configurability. Out-of-band (OOB) powerful modulated TX-leakage due to limited antenna/duplexer isolation imposes challenges that are more severe than those posed by continuous-wave (CW) blockers by several orders of magnitude, including cross-modulation, second-order intermodulation and TX noise in the RX band (Fig. 20.6.1). Analysis shows that in the face of 0dBm peak TX leakage and a -30dBm CW in-band jammer, to achieve -90dBm sensitivity with 7dB SNR over 2MHz signal BW, a transceiver must exhibit +30dBm receiver OOB IIP3 and -160dBc/Hz TX noise in RX band.