[en] A 6-9 GHz ultra-wideband CMOS power amplifier (PA) for the high frequency band of China's UWB standard is proposed. Compared with the conventional band-pass filter wideband input matching methodology, the number of inductors is saved by the resistive feedback complementary amplifying topology presented. The output impendence matching network utilized is very simple but efficient at the cost of only one inductor. The measured S₂₂ far exceeds that of similar work. The PA is designed and fabricated with TSMC 0.18 μm 1P6M RF CMOS technology. The implemented PA achieves a power gain of 10 dB with a ripple of 0.6 dB, and S₁₁ < -10 dB over 6-9 GHz, S₂₂ < -35 dB over 4-10 GHz. The measured output power at the 1 dB compression point is over 3.5 dBm from 6 to 9 GHz. The PA dissipates a total power of 21 mW from a 1.8 V power supply. The chip size is 1.1 x 0.8 mm². (semiconductor integrated circuits)

[en] In this manuscript, we demonstrate an all-fiberized master-oscillation-power-amplifier (MOPA) structured linearly-polarized narrowband random laser. The seed source is a narrowband random-polarized random fiber laser (RFL) in a half-opened cavity with a maximum output power of 0.981 W and a linewidth of 0.1 nm. Utilizing a polarization-dependent isolator as a polarizer, a linearly-polarized narrowband seed laser can be obtained. As for the main amplifier, a pump-limited 381.1 W amplified linearly-polarized narrowband random laser can be achieved with a linewidth of 0.13 nm (33.36 GHz) and a polarization degree of 92.33% (∼11 dB). The performance of the system is limited by the generation of mode instability (MI) effects, and hence, the worsening of temporal stability and the reduction of beam quality. Furthermore, significant tail broadening of the output spectrum can be measured. As the output and backward powers increase monotonously with the boosting of pump power, we conclude that further power scaling of this system with good linewidth, polarization, beam quality and temporal stability performance can be achieved with effective mitigation of the MI effect. This work can expand our comprehension on the spectral evolution property of RFL in the power scaling process and provide a possible solution for the obtaining of powerful linearly-polarized narrowband fiber source. (letter)

[en] This paper presents a 2.4 GHz power amplifier (PA) designed and implemented in 0.35 μm SiGe BiCMOS technology. Instead of chip grounding through PCB vias, a metal plate with a mesa connecting ground is designed to decrease the parasitics in the PCB, improving the stability and the gain of the circuit. In addition, a low-pass network for output matching is designed to improve the linearity and power capability. At 2.4 GHz, a P^1dB of 15.7 dBm has been measured, and the small signal gain is 27.6 dB with S¹¹ < -7 dB and S²² < -15 dB. (semiconductor integrated circuits)

[en] A new 200 Mhz power amplifier system has been used operationally on the Bevatron Local Injector 20 MEV LINAC with two different power tetrodes: an EIMAC 4CWW100,000E and a Thomson-Houston TH-535. The same basic anode and grid structures were used with both tubes. The system has provided increased power output over the 4616 tetrode previously used. Maximum operational gradients were achieved with both tubes. System testing, tube interchangeability, and high power operating data will be presented

[en] A transformer-based CMOS power amplifier (PA) is linearized using an analog predistortion technique for a 2.5-GHz m-WiMAX transmitter. The third harmonic of the power stage and driver stage can be cancelled out in a specific power region. The two-stage PA fabricated in a standard 0.18-μm CMOS process delivers 27.5 dBm with 27% PAE at the 1-dB compression point (P_1dB) and offers 21 dB gain. The PA achieves 5.5 % EVM and meets the spectrum mask at 20.5 dBm average power. Another conventional PA with a zero-cross-point of g_m3 bias is also fabricated and compared to prove its good linearity and efficiency. (semiconductor devices)

[en] A three-stage power amplifier is developed for an IR terawatt femtosecond laser system generating 80-fs, 1240-nm pulses with energy of up to 90 mJ, a pulse repetition rate 10 Hz, and the intensity contrast above 10⁶. The efficiencies of different schemes of multipass amplifiers are compared. It is shown that an optical scheme with plane mirrors is optimal for achieving the terawatt power level. (lasers and amplifiers)

[en] The amplitude and phase variability among combiner inputs result in combining loss and degradation in amplifier’s combining efficiency. An analysis on combining efficiency is presented to understand the effect of variability in the combiner inputs and combiner transmission parameters. For symmetrical combiners, combining efficiency depends on the variance of its input voltages and intrinsic loss in combiner itself, whereas combining efficiency depends on mean of its inputs as well. Lower bound on combining efficiency has also been derived. The lower bound presented here offers an improvement over the lower bound reported in earlier works. Knowing the maximum spread in amplifier gain (magnitude and phase) in a production process, it is possible to predict the worst case combining efficiency. The derivations have been validated with the help of system simulation using measured results of power combiner.

[en] This paper presents the design, simulation in CST Microwave Studio, some fabrication issues/aspects during development process and the measured results of a RF high power four way combiner operating at 37.8 MHz. The combiner will be used for development of 3 kW solid state RF high power amplifier, which is planned to be used as replacement of driver amplifier for RFQ transmitter in RIB project at VECC. The combiner is based on Wilkinson's combining technique in a coaxial line (O.D. 3.125 inches) structure, in which the hollow inner conductor has been split into four splines to form the required impedance transmission lines, which are connected by disc at output end. Tapered coaxial line based matching sections are designed and incorporated at the output end for impedance matching to the standard 7/8 inches coaxial 50 ohm output port. The entire structure was simulated in CST MW studio with copper material and the simulation results shows very good input and output port matching of less than -20 dB, low excess insertion loss of less than 0.2 dB above ideal insertion loss of -6 dB, port isolation greater than 20 dB, small transmission and phase variations from input to output port of less than 0.15 dB and less than 2 degree respectively. Some mechanical aspects of importance to RF performance, during fabrication of RF combiner are also presented. The measurement results using VNA are presented here and they are in good agreement with simulated results. The RF combiner has been tested to few hundred watts of output power and further tests for operation to full power are being carried on. (author)

[en] We demonstrate substantial power gain with a superconducting transition detector. Theoretically we describe the properties of the detector as a power amplifier. In our first experiments power gain of ∼25 was reached, in good agreement with the theory. The gain facilitates noise matching of the readout circuit to the detectors in the case of cryogenic time-division multiplexing.

[en] Based on the Gummel-Poon model of BJT, the change of the DC bias as a function of the AC input signal in RF linear power amplifiers is theoretically derived, so that the linearity of different DC bias circuits can be interpreted and compared. According to the analysis results, a quantitative adaptive DC bias circuit is proposed, which can improve the linearity and efficiency. From the simulation and test results, we draw conclusions on how to improve the design of linear power amplifier.