A Ka-band low-noise amplifier using semicircle stacked-GCPW transmission line

A high-gain Ka-band 0.18-μm CMOS low-noise amplifier with semicircle stacked grounded coplanar waveguide (SCS-GCPW) structure transmission line is proposed. SCS-GCPW transmission line is adopted to reduce the signal loss by shaping the electric fields under the signal line especially at microwave and millimeter wave applications. The SCS-GCPW demonstrated a similar electric field distribution of coaxial cable and achieved a substrate dielectric attenuation constant of 0.075 Np/m. It is superior to 0.081 Np/m and 0.144 Np/m of traditional microstrip transmission line and CPW transmission line, respectively. By adopting the low loss SCS-GCPW transmission line, the Ka-band LNA demonstrated a 24.5 dB gain together with a noise figure (NF) of 7.5 dB at 33 GHz operation. The measured output power 1 dB compression point (P _{1 dB}) was -2 dBm. The dc power consumption was 40 mW and chip size was 0.6 × 1 mm² for this Ka-band LNA.