A highly linear receiver front-end employing modified derivative superposition method with tuned inductors for 5.25 GHz

Abstract

We design a highly linear CMOS RF receiver front-end operating in the 5GHz band using the modified derivative superposition (DS) method with one- or two-tuned inductors in the low noise amplifier (LNA) and mixer. This method can be used to adjust the magnitude and phase of the third-order currents at output, and thus ensure that they cancel each other out. We characterize the two front-ends by the third-order input intercept point (IIP3), voltage conversion gain, and a noise figure based on the TSMC 0.18μm RF CMOS process. Our simulation results suggest that the front-end with one-tuned inductor in the mixer supports linearization with the DS method, which only sacrifices 1.9dB of IIP3 while the other performance parameters are improved. Furthermore, the front-end with two-tuned inductors requires a precise optimum design point, because it has to adjust two inductances simultaneously for optimization. If the inductances have deviated from the optimum design point, the front-end with two-tuned inductors has worse IIP3 characteristic than the front-end with one-tuned inductor. With two-tuned inductors, the front-end has an IIP3 of 5.3dBm with a noise figure (NF) of 4.7dB and a voltage conversion gain of 23.1dB. The front-end with one-tuned inductor has an IIP3 of 3.4dBm with an NF of 4.4dB and a voltage conversion gain of 24.5dB. There is a power consumption of 9.2mA from a 1.5V supply.