This paper presents a wideband inductorless Balun-LNA targeting spin torque oscillator-based magnetic field sensing applications. The LNA consists of a CS stage combined with a cross-coupled CG stage, which offers wideband matching, noise/distortion cancellation and gain boosting, simultaneously. The Balun-LNA is implemented in a 65 nm CMOS technology, and it is fully ESD-protected and packaged. Measurement results show a bandwidth of 2 GHz–7 GHz, a voltage gain of 20 dB, an IIP3 of +2 dBm, and a maximum NF of 5 dB. The LNA consumes 3.84 mW from a 1.2 V power supply and occupies a total silicon area of 0.0044 mm2. The measurement results demonstrate that the proposed Balun-LNA is highly suitable for the STO-based field sensing applications.