A 28-GHz Low-Power Variable-Gain Low-Noise Amplifier Using Twice Current Reuse Technique

In this letter, a 28-GHz low-power variable-gain low-noise amplifier (VGLNA) is designed for fifth-generation millimeter-wave applications and implemented using the twice current reuse (CR) technique and a tunable load. This amplifier employing the twice CR technique exhibits low dc power while delivering enhanced gain. The gain control (GC) range of the amplifier is extended using a tunable load, which is composed of a pMOS device and an inductance, and the phase variation is improved by resonating the inductance with the parasitic capacitance of the intrastage CR amplifier. Because the tunable load selectively attenuates only ac signals, ${\mathrm{ IP}}_{1 \rm dB}$ can be proportionally increased by reducing the gain. At 28 GHz, the measured gain and GC range are 21.2 and 13.8 dB, respectively. In the entire GC range, the measured ${\mathrm{ IP}}_{1 \rm dB}$ ranges from −20 to −7 dBm, the noise figure (NF) ranges from 3.7 to 6.8 dB, and the RMS phase error is 1.05° at 28 GHz. At a supply voltage of 1.2 V, the dc power of the proposed VGLNA is only 5.0 mW. These results highlight that the proposed VGLNA has the lowest dc power, higher gain, and better figure of merit compared to other works.