Broadband GaN HEMT power amplifier with shunt feedback and push-pull technique is presented. Shunt-feedback and push-pull realization provide the robust broad bandwidth covering VHF and low-frequency UHF bands. The benefit due to the feedback presented in the form of shunt-shunt network on power amplifier module provides the linear and broadband frequency amplification. The push-pull topology provides enhanced efficiency and high power generation along with the cancellation of the second-order distortions and thus helps to compensate for the efficiency degradation from the feedback. These techniques are realized with the help of in-house designed GaN HEMT transistor, which provides high power, good efficiency, and high reliability (bandgap). The prototype was realized in 0.25μm GaN HEMT, operates from 30 to 520 MHz, and dissipates 650mA of quiescent current from 28V supply. The power amplifier delivered a saturated output power of > 43 dBm and < 1 dB gain flatness with > 40% PAE at 20W output power. The linearity of the amplifier was characterized by the two-tone injection test. The measurement result shows that the 3rd-order intermodulation distortion tones are below -35 dBc at 35 dBm output power.

This paper presents a low-noise amplifier (LNA) with single to differential conversion (Balun) for multi-standard radio applications. The proposed LNA combines a common-gate (CG) stage for wideband input matching and a common-source (CS) stage to cancel the noise and distortion of the CG stage. Using the proposed technique, a low noise figure (NF) is achieved while providing a wideband of operation. Furthermore, a feedback connection from the CS stage to the gate of the CG is employed to boost the transconductance of the CG stage ($g{m}_{CG}$), and an additional complementary transistor is applied at the CS stage using current reuse to increase the overall transconductance of the CS stage ($g{m}_{CS}$) without increasing the power consumed by the stage. This LNA was designed using TSMC 65 nm technology, and post-layout simulation results show operation across 0.5–5 GHz, a maximum power gain of 20 dB, 4 dB minimum NF, and third-order intercept point (IIP3) of −10 dBm while consuming only 5 mW of power from a 1.2 V supply.

This paper presents the analysis and design of the harmonic rejection (HR) low-noise amplifier (LNA) with the fully passive source degeneration notch filter. The proposed HR LNA provides the rejection for the strong harmonics ( $3_{rd}$ ) of the local oscillator (LO) frequencies, where the HR mixer does not provide sufficient HR performance. The proposed $3_{rd}$ harmonic notch filter modulates the source degeneration factor and the impedance matching performance thereafter. This effect further helps the blocking of the harmonic signal. The proposed LNA provides 11 dB gain at the fundamental frequency (2.1 GHz) while rejecting the 3rd harmonic component by 37 dBc. Compared to the conventional LNA, the 3rd harmonic notch performance is improved by 23 dB. Additionally, the LNA achieves a minimum noise figure of 3.1 dB, third order input intercept point ( $II{P}_3$ ) of 0.5 dBm, input reflection (S ${}_{11}$ ) below −10 dB from 1.8 GHz–2.3 GHz operational frequency range, and consumed 19 mW of power from a 1.2 V supply.

1. For each frequency, f₁, to be curve fitted, reference materials are injected into the sensing capacitor and its |S₂₁| is measured through a VNA.

Objectives : The optimal ultrasonic irradiation conditions were derived through laboratory-scale experiments to evaluate growth inhibition effect of Microcystis aeruginosa (M. aeruginosa), which is the main specie of Cyanobacterial Harmful Algal Blooms (CyanoHABs) in Republic of Korea.Methods : The experiment was conducted by changing ultrasonic frequency, intensity, and initial cell concentration to observe the growth inhibition effect of M. aerginosa. The experiment was performed using shielded acrylic reactor [20 cm (W) × 20 cm (L) × 30 cm (H)]. Experiments were conducted using large volume (7.2 L) of water samples with high concentrations of M. aeruginosa, and the ultrasonic irradiation time was fixed at 3 hours.Results and Discussion : In all experiments, pictorial view of M. aeruginosa samples, chlorophyll-a (Chl-a) and cell number of M. aerginosa were observed. As a result of ultrasonic irradiation on M. aeruginosa, the decrease in both Chl-a concentration and cell number of M. aeruginosa was monitored after sonication compared to the decrease during sonication. In addition, the rebound growth was confirmed after certain period of growth inhibition of M. aeruginosa. The optimal ultrasonic irradiation conditions for the growth inhibition of M. aeruginosa were obtained at the lower frequency and the higher intensity. Whereas algal growth inhibition was observed with high concentration (4.5 × 106 cells mL-1) of M. aeruginosa, algal growth inhibition was not monitored with low concentration (1.1 × 106 cells mL-1) of M. aeruginosa.Conclusion : Through this study, the algal growth inhibition by ultrasonic was effective. Although the growth inhibition effect persisted for a certain period of time, subsequent regrowth was observed. Therefore, periodic ultrasonic irradiation is necessary for long-term growth inhibition of algal in field applications.