## 4 Simulation Results
This is slightly more than the minimum cancellation of 27 dB that is guaranteed by the canceler resolution. However, it is noticed that the effective OOB IIP3 improvement is much less than the cancellation. This is due to the canceler nonlinearity, ultimately limiting the effective receiver IIP3. This is shown in Figure 16, where the cancellation is varied by adjusting the canceler control bits. When the cancellation is above 18 dB the effective IIP3 remains constant, limited by the canceler intrinsic nonlinearities. Additional critical system performance test that demonstrates the system full-duplex functionality is carried out by considering an in-band two-tone test with both tones applied at the canceler input, representing the TX signal. The tones are placed at 6 MHz and 10 MHz offset from the LO and the IM3 falls at 2 MHz. When the canceler is disabled, the IIP3 is equal to 5.3 dBm. When the canceler is turned on and set to the proper setting for SI cancellation, the IIP3 improves to 21 dBm, as is illustrated by the simulation results in Figure 17. One interesting observation is that the result shows that the output IM3 of the canceler becomes dominant at the RX input. In fact, in the SI cancellation full-duplex system, the effective receiver IIP3 is given by the canceler IIP3 plus 3 dB, due to the LNA input transformer gain (\(-3\) dB). The IIP3 of the canceler is thus, important and must be designed to be sufficiently high to guarantee both FDD and full-duplex operations. Another performance evaluation of the receiver with the canceler is the 1 dB compression point (P\({}_{\text{1 dB}}\)). With the canceler disabled, the receiver, due to the presence of SI saturates, thereby desensitizing the RX signal. The gain 1 dB compression plot due to an in-band SI is shown in Figure 18a. The simulation result is obtained with the SI placed at 10 MHz away from the LO (at 2 GHz) while the Rx signal is placed at 3 MHz offset. The in-band P\({}_{\text{1 dB}}\) referred to the receiver input is \(-25\) dBm. When the canceler is turned ON, with more than 30 dB of SI cancellation, P\({}_{\text{1 dB}}\) is pushed to 4 dBm. For the OOB P\({}_{\text{1 dB}}\) evaluation, the SI is placed 100 MHz away from the LO and the Rx signal is kept at 3 MHz. The receive signal is swept until saturation occurred at 1.7 dBm referred to the RX port while  
Figure 16: Effective OOB IIP3 vs. SI cancellation. Figure 17: IIP3 with two-tone cancellation at receiver (RX) input. the canceler is disabled. When the canceler is turned on, the P1 dB is pushed to 5 dBm, as plotted in Figure 18b. This work is benchmarked against prior works focussing on SI cancellation for FDD and full-duplex systems [12; 18; 20; 21] as shown in Table 1. The system achieves low noise figure and high effective IIP3 thanks to the improvement of the canceler cross-modulation distortion, while dissipating low power. TX leakage cancellation is performed in front of the LNA achieving more than 30 dB of cancellation over 80 MHz bandwidth. This solution addresses also the issues of receiver IIP2 and reciprocal mixing. Among prior works, only [18], which is tailored towards FDD applications, achieves similar IIP3 values and higher SI power handling capabilities. However, the TX leakage is effectively cancelled only after down-conversion and recombination between common-gate and common-source paths, making it prone to IIP2 and reciprocal mixing. Furthermore [18] has much higher power dissipation and higher NF. In [12] power dissipation is very low but the maximum SI is only \(-20\) dBm. However, to be fair, it must be noticed that all of the other works reported in the table report measured results, while in this work we are presenting only simulation results.