Wideband CMOS low noise amplifier including an active balun

An inductorless LNA with active balun is proposed for multi-standard radio applications between 100MHz and 6GHz [1]. It exploits a combination of a common-gate (CG) stage and an common-source (CS) stage with replica biasing to maximize balanced operation, while simultaneously canceling the noise and distortion of the CG-stage. In this way, a Noise Figure (NF) close to or below 3dB can be achieved, while good linearity is possible if the CS-stage is carefully optimized. Moreover, good output balancing can be achieved. The best performance is achieved between 300MHz to 3.5GHz with gain and phase errors below 0.3dB and ±2degrees, 15dB gain, S11<−14dB, IIP3 = 0dBm IIP2 higher than +20dBm at a total power consumption of 21mW. The circuit is fabricated in a baseline 65nm CMOS process, with an active area of only 0.01mm2. The circuit simultaneously achieves impedance matching, noise canceling, distortion canceling and a well balanced output.