A 39/48 GHz Switchless Reconfigurable Low Noise Amplifier Using Common Gate and Coupled-Line-Based Diplexer

This brief presents a switchless dual-band low-noise amplifier (LNA) that can be reconfigured to include n260 (37–40 GHz) and n262 (47.2–48.2 GHz) millimeter-wave (mm-Wave) dual bands. The proposed reconfigurable LNA is designed to separate and isolate two bands, using a common gate and coupled-line-based diplexer for the inter-stage of cascade amplifiers. A common gate amplifier has the advantage of simultaneously selecting the signal path and amplifying the signal power according to a band, using an impedance variation between the “on/off” conditions of gate bias. In addition, the coupled-line-based diplexer can be optimized to exhibit high isolation characteristics between frequencies using high and low-pass characteristics. The designed reconfigurable LNA is fabricated with the 0.15- $\boldsymbol{\mu }\mathbf {m}$ GaAs pHEMT process. With the high frequency (HF) mode, the reconfigurable LNA achieves a measured gain of 19.2 dB at the center frequency, noise figure, and ${\mathrm{ OP}}_{\mathrm{ 1dB}}$ of 48 GHz, 4.8 dB, and 6.88 dBm, respectively. In the low frequency (LF) mode, the reconfigurable LNA exhibits a measured gain of 24.8 dB at the center frequency, noise figure, and ${\mathrm{ OP}}_{\mathrm{ 1dB}}$ of 39 GHz, 3.9 dB, and 6.80 dBm, respectively. The chip occupies a core area of $3.04~{mm}^{2}$ , which consumes $61.4~\mathbf {mW}$ and $64.7~\mathbf {mW}$ in the HF and LF modes, respectively.