Gain Characteristics of Fiber Optical Parametric Amplifier

The theory model of fiber optical parametric amplifier (FOPA) was introduced, which is based on optical nonlinear effect. And then numerical simulation was done to analyze and discuss the gain spectral characteristics of one-pump and two-pump FOPA. The results show that for one-pump FOPA, when pump wavelength is near to fiber zero-dispersion wavelength(ZDW), the gain flatness is better, and with the increase of the pump power, fiber length and its nonlinear coefficient, the gain value will increase while the gain bandwidth will become narrow. For two-pump FOPA, when the pump central wavelength is near to fiber ZDW, the gain flatness is better. Moreover, by decreasing the space of two pumps wavelength, the gain flatness can be improved. Finally, some problems existing in FOPA were addressed.

A gain-flatness optimization solution for feedback technology of wideband low noise amplifiers

The S parameter expression of high-frequency models of the high electron mobility transistors (HEMTs) with basic feedback structure,especially the transmission gain S 21,is presented and analyzed.In addition,an improved feedback structure and its theory are proposed and demonstrated,in order to obtain a better gain-flatness through the mutual interaction between the series inductor and the parallel capacitor in the feedback loop.The optimization solution for the feedback amplifier can eliminate the negative impacts on transmission gain S 21 caused by things such as resonance peaks.Furthermore,our theory covers the shortage of conventional feedback amplifiers,to some extent.A wideband low-noise amplifier (LNA) with the improved feedback tech-nology is designed based on HEMT.The transmission gain is about 20 dB with the gain variation of 1.2 dB from 100 MHz to 6 GHz.The noise figure is lower than 2.8 dB in the whole band and the amplifier is unconditionally stable.

An 8–18 GHz power amplifier with novel gain fluctuation compensation technique in 65 nm CMOS

A wideband CMOS power amplifier with high gain and excellent gain flatness for X-Ku-band radar phased array is proposed in this paper. Excellent gain flatness is achieved with transformer based matching networks(TMNs), in which the gain fluctuation of an inter-stage matching network can be compensated by the proposed design methods. The circuit is fabricated in the TSMC 65 nm RF CMOS process. The proposed technique is verified by the measurement results, which show that the wideband PA achieves gain of 21-22.5 dB with only±0.75 dB gain fluctuation and 13-14.6 dBm flat output power between 7.5 and 15.5 GHz,and a little more ripple in the rest of the X-Ku band due to the inaccuracy of passive modelling at high frequency. The circuit delivers saturated and 1 dB-compressed output power of 14.6 and 11.3 dBm respectively at 13 GHz, for a maximal poweradded efficiency(PAE) of 23%.

A 0.18 μm CMOS 3-5 GHz broadband flat gain low noise amplifier

A 3-5 GHz broadband flat gain differential low noise amplifier（LNA） is designed for the impulse radio ultra-wideband（IR-UWB） system.The gain-flatten technique is adopted in this UWB LNA.Serial and shunt peaking techniques are used to achieve broadband input matching and large gain-bandwidth product（GBW）.Feedback networks are introduced to further extend the bandwidth and diminish the gain fluctuations.The prototype is fabricated in the SMIC 0.18μm RF CMOS process.Measurement results show a 3-dB gain bandwidth of 2.4-5.5 GHz with a maximum power gain of 13.2 dB.The excellent gain flatness is achieved with±0.45 dB gain fluctuations across 3-5 GHz and the minimum noise figure（NF） is 3.2 dB over 2.5-5 GHz.This circuit also shows an excellent input matching characteristic with the measured S11 below-13 dB over 2.9-5.4 GHz.The input-referred 1-dB compression point（IP1dB） is-11.7 dBm at 5 GHz.The differential circuit consumes 9.6 mA current from a supply of 1.8 V.

A flat gain GaN MMIC power amplifier for X band application

A flat gain two-stage MMIC power amplifier with a 2.8 GHz bandwidth is successfully developed for X band frequency application based on a fully integrated micro-strip Al GaN/GaN HEMT technology on a semiinsulating Si C substrate. Designed with a binary-cluster matching structure integrated with RC networks and LRC networks, the developed power MMIC gets a very flat small signal gain of 15 dB with a gain ripple of 0.35 dB over 9.1–11.9 GHz at the drain bias of 20 V. These RC networks are very easy to improve the stability of used GaN HEMTs with tolerance to the MMIC technology. Inside the frequency range of 9–11.2 GHz where the measurement system calibrated, the amplifier delivers a pulsed output power of 39 dBm and an associated power added efficiency of about 20% at 28 V without saturation, as the available RF power is limited.