Noise canceling LNA with gain enhancement by using double feedback

• We present a balun LNA with high gain and low noise figure by using active loads.
• A double feedback technique for gain enhancement and noise figure reduction is used.
• Two RF front-end receivers using a 130 nm CMOS technology were implemented: (1) using an LNA with active loads; (2) using an LNA with active loads and local double feedback.

In this paper we present a balun low noise amplifier (LNA) in which the gain is boosted by using a double feedback structure. The circuit is based on a conventional balun LNA with noise and distortion cancelation. The LNA is based on the combination of a common-gate (CG) stage and common-source (CS) stage. We propose to replace the load resistors by active loads, which can be used to implement local feedback loops (in the CG and CS stages). This will boost the gain and reduce the noise figure (NF). Simulation results, with a 130 nm CMOS technology, show that the gain is 24 dB and the NF is less than 2.7 dB. The total power dissipation is only 5.4 mW (since no extra blocks are required), leading to a figure-of-merit (FOM) of 3.8 mW−1 using a nominal 1.2 V supply. Measurement results are presented for the proposed DFB LNA included in a receiver front-end for biomedical applications (ISM and WMTS).