A single‐to‐differential low‐noise amplifier (LNA) is proposed for low‐power medical devices in the frequency band of 401–406 MHz. The proposed LNA avoids the use of surface acoustic wave (SAW) filter and additional balun in RF receiver front‐end. The LNA comprises inductive degeneration common source (IDCS) technique (stage I) and a cascaded common source circuit (stage II). The stage‐II is stacked on top of stage‐I. The proposed balun LNA incorporates single to differential (SD) conversion for minimum gain and phase error. A compensation bias circuit is proposed to minimise variations in parameters of LNA against process corners, supply voltage and temperature (PVT). An upsurge balun LNA is designed in UMC 0.18‐µm CMOS technology, the DC power consumption is 290 µW under a supply voltage of 1 V and the minimum noise figure is 3 dB. The die area of LNA including buffers and bias circuit is 850 µm × 978 µm. The worst‐case post layout simulation results show a gain and phase error of 0.8 dB and 10°. The percentage variation of gain and NF against PVT is reduced by 55 and 48%. Furthermore, the balun LNA has out of band rejection at the roll‐off rate better than 70 dB/dec.