High Efficiency C-band Research Articles

A high efficiency C-band internally-matched harmonic tuning GaN power amplifier

In this paper, a high efficiency C-band gallium nitride (GaN) internally-matched power amplifier (PA) is presented. This amplifier consists of 2-chips of self-developed GaN high-electron mobility transistors (HEMTs) with 16mm total gate width on SiC substrate. New harmonic manipulation circuits are induced both in the input and output matching networks for high efficiency matching at fundamental and 2nd-harmonic frequency, respectively. The developed amplifier has achieved 72.1% power added efficiency (PAE) with 107.4W output power at 5GHz. To the best of our knowledge, this amplifier exhibits the highest PAE in C-band GaN HEMT amplifiers with over 100W output power. Additionally, 1000 hours’ aging test reveals high reliability for practical applications.

A C-Band Internally-Matched High Efficiency GaN Power Amplifier

We present a design and realization of a high efficiency C-Band (5.2 GHz–5.8 GHz) internally-matched gallium nitride (GaN) power amplifier (PA). To reduce power dissipation and to achieve high efficiency, both input and output matching networks, along with 2nd-harmonic modulation circuits, are designed accurately according to the source and load optimum impedances extracted by source-pull and load-pull measurements. The PA realizes an excellent rf performance under a pulsed condition, demonstrating a maximum output power of 52.2dBm (164 W) with at least 13.5dB gain in the frequency range from 5.2 GHz to 5.8 GHz (10% relative bandwidth). At the same time, a power-added efficiency (PAE) of 69.4% is observed at 5.6 GHz and over 65.0% throughout the whole bandwidth. The PAE is the state-of-art performance for C-band GaN high-electron-mobility transistor PA with such high output power, to the best of our knowledge.

71% PAE C‐band GaN power amplifier using harmonic tuning technology

A high-efficiency C-band internally matched power amplifier, developed with 12 mm AlGaN/GaN high-electron mobility transistors is described. The second-harmonic frequency (2f 0) tuning network is applied to confine the impedance at 2f 0 in safe efficiency regions. The packaged power amplifier achieves 71% power-added efficiency (PAE) and 102 W output power, associated with 17 dB power gain. The PAE is believed to be the highest of the C-band GaN power amplifiers reported to date.

Study of superradiance based on a low-voltage backward wave oscillator

According to the small size requirement for wide-band high-power microwave radiation, a superradiance backward wave oscillator (BWO) is proposed to generate such high-power microwave radiation with a low voltage (∼20 kV) pulse power supply and low guiding magnet field (∼0.1 T). In order to get a high-efficiency C-band superradiance BWO with a low beam voltage and a low guiding magnet field, the mechanism of superradiance in a BWO is explored in particle-in-cell simulation. With the oversized structure, the simulation shows that a microwave power of 405 kW with a frequency of 5.6 GHz and a spectrum width of 500 MHz can be obtained with a voltage of 23 kV and magnetic field of 0.1 T.

Low convergent confined-flow Pierce gun for a space TWT

An approach for designing an electron gun for a high efficiency, high linearity space traveling wave tube (TWT), has been presented. A low convergent (<10 : 1) Pierce electron gun of beam perveance 0.43 μP has been designed for a high gain, high linearity and high efficiency C-band 60 W Space TWT using in-house developed two-dimensional FDM based gun and collector simulation code PIERCE. In this gun, the first anode (isolated from the ground anode) has been kept nearly 100 V above the ground anode to act as an ion barrier for increasing cathode life and to regulate beam current over the lifetime of the tube. An M-type dispenser cathode of diameter 3.20 mm has been used for cathode loading of less than 1.0 A/cm2 and heater wattage around 3.0 W. The magnetic focusing with integral-pole-piece barrel assembly and periodic-permanent magnets (PPM) have been designed using in house developed two-dimensional FDM based code SUNMAG. The practical problem of linking requisite cathode flux to the cathode for confined flow of the electron beam with low convergence factor has been sorted out by gradually increasing the PPM magnetic field. The magnetic field has been increased in steps from the gun and over the first five magnets varying from Brillouin field (B B) value to twice B B for achieving the electron beam with scalloping less than 10%. Agreements between the simulated results and the experimental results for the beam current and magnetic field profile have been achieved within 8%. The dynamic beam transmission (under rf operation of the tube) has been achieved better than 98% in the tube.