A novel ultra-low power (ULP) low noise amplifier using differential inductor feedback

A novel ultra-low power (ULP) low noise amplifier (LNA) is proposed for low-power radio-frequency (RF) wireless radios. Using the differential inductor feedback structure along with the neutralizing capacitor, this configuration doubles the effective g. of the input transistor, while cancelling out the feed forward and LO leakage through the gate-drain capacitor. In this design, the input device is biased to operate in moderate inversion region to achieve microwatt power dissipation. Experimental results indicate a power dissipation of 100 mu W, a noise-figure (NF) of 3.9dB, and a forward gain of 16.8dB. The LNA also exhibits an IIP3 of -11.2dBm and the input referred -1dB compression point of -21dBm. The circuit was fabricated in Jazz Semiconductor's CMOS 0.18 mu m process and was powered up using a supply voltage of 1V. For comparison purpose, a ULP common-gate LNA was also designed and fabricated using the same process. Experimental results show that the proposed LNA exhibits higher gain, lower NF, and better linearity.