A Ku-Band Filtering LNA with Flat Gain and High Linearity

This paper introduces a low-noise amplifier (LNA) capable of covering the entire Ku band with filtering function and good linearity. This paper uses a feedback circuit based on coupling line structure to compensate for the gain roll-off of the transistor. The coupling line in the feedback structure is also used to realize the filter function of the low noise amplifier. A multigate transistor structure (MGTR) based on the derivative superposition (DS) principle to improve the intermodulation distortion of the low noise amplifier. The amplifier has an average gain of 24dB, a noise figure of 1.5dB and an IIP3 of 6dBm. To further enhance the filtering characteristics of the amplifier within the 14-15 GHz frequency range, this paper presents the design of a dielectric waveguide bandpass filter based on Ferro-A6M material, achieving band interpolation loss less than 0.8dB, low-end out-of-band 30MHz attenuation reaches 23.6dB, high-end out-of-band 100MHz attenuation reaches 47dB. The HFSS model of this filter was imported into ADS for system-level cascaded simulations, resulting in excellent rectangular coefficient and out-of-band suppression.