A methodology for obtaining semi-custom high-power amplifiers (HPAs) is described. The semi-custom concept pertains to the notion that a selectable output power is attainable by replacing only transistors. To compensate for the mismatch loss, a new output matching network that can be easily tuned by wiring is proposed. Design equations were derived to determine the circuit parameters and specify the bandwidth limitations. To verify this methodology, a semi-custom HPA with GaN HEMTs was fabricated in the S-band. A selectable output power from 240 to 150 W was successfully achieved while maintaining a PAE of over 50% in a 19% relative bandwidth.

A four-stage power amplifier (PA) with 10 GHz 1-dB bandwidth (56–66 GHz) is presented. The broadband performance is achieved owing to π-section interstage matching network. Three-stage-current-reuse topology is proposed to enhance efficiency. The amplifier has been fabricated in 65 nm digital CMOS. 18 dB power gain and 9.6 dBm saturated power (Psat) are achieved at 60 GHz. The PA consumes current of 50 mA at 1.2 V supply voltage, and has a peak power-added efficiency (PAE) of 13.6%. To the best of the authors' knowledge, this work shows the highest PAE among the reported CMOS PAs that covers the worldwide 9 GHz ISM millimeter-wave band with less-than-1.2 V supply voltage.

This paper presents an ultra-wideband amplifier embedded with band-pass filter design. The scattering parameters of a frequency-domain GaAs field effect transistor are converted into z-domain representations by employing the weighted linear least squares method. A least squares scheme is employed to obtain characteristic impedances of transmission line elements that form the amplifier having a flat gain in the passband and good fall-off selectivity in the stopband. Experimental results illustrate the validity of the proposed design method.

An InGaP/GaAs HBT MMIC amplifier with an active balun has been developed for ultra-wideband radio systems (UWB). The MMIC was designed to drive a self-complementary antenna with a balanced mode, where an input impedance is 60π ohms. The MMIC consists of a common mode negative feed back ultra-wideband amplifier circuit, an active balun circuit, and a high impedance drive circuit. The developed amplifier provides a 3-dB gain roll-off bandwidth from 2.4 GHz to 10.8 GHz with a 14.1-dB linear power gain, and a linear power output up to 3 dBm. The developed amplifier with the active balun provides a 3-dB gain roll-off bandwidth from 2.3 GHz to 8.6 GHz with a 21.3-dB power gain in a balanced mode, and a linear power output up to 0.6 dBm. The measured total group delay is less than 32 psec. Output signals at the balanced output terminals of the MMIC were kept inverted with a steep pulse shape for an impulse input signal of 57-psec pulse width.

We have developed the design procedure of multi-wavelength pumped Raman amplifiers, introducing superposition rule and account for pump-to-pump energy transfer. It is summarized with respect to the pumping wavelength and power allocation. The comparisons between simulated and experimental results are presented. Section 2 reviews the fundamentals of Raman amplifier. In this section, Raman gain spectra measured for different fibers are presented and the difference among the spectra is discussed. Section 3 describes the way to determine the pumping wavelength allocation by introducing superposition method. By means of this design method, some optimized design examples are presented, where the peak levels of Raman gain are fixed to 10 dB for the wavelength range from 1525 nm to 1615 nm (C- plus L-band) in all cases. From these results, it is confirmed that better gain flatness can be obtained by using the larger number of pumps. Section 4 explains how the pump-to-pump energy transfer changes the gain profile by experimental and simulated results. In this section, simulation modeling to perform precise numerical simulation is also presented. From the above discussion, the design procedure can be simplified: (1) one determines pump wavelengths with which a desired composite Raman gain can be obtained by adding in logarithmic scale individual Raman gain spectra shifted by the respective wavelength differences with adequate weight factors. And (2), one predicts how much power should be launched in order to realize the weight factors through precise numerical simulations. Section 5 verifies the superposition rule and the effect of pump-to-pump energy transfer by comparing a measured Raman gain with a superposed one. The agreement of two gain profiles shows that the multi-wavelength pumped Raman gain profile contains only the individual gain profiles created by the respective pump wavelengths. Section 6 concludes this paper.

We have developed the design procedure of multi-wavelength pumped Raman amplifiers, introducing superposition rule and account for pump-to-pump energy transfer. It is summarized with respect to the pumping wavelength and power allocation. The comparisons between simulated and experimental results are presented. Section 2 reviews the fundamentals of Raman amplifier. In this section, Raman gain spectra measured for different fibers are presented and the difference among the spectra is discussed. Section 3 describes the way to determine the pumping wavelength allocation by introducing superposition method. By means of this design method, some optimized design examples are presented, where the peak levels of Raman gain are fixed to 10 dB for the wavelength range from 1525 nm to 1615 nm (C- plus L-band) in all cases. From these results, it is confirmed that better gain flatness can be obtained by using the larger number of pumps. Section 4 explains how the pump-to-pump energy transfer changes the gain profile by experimental and simulated results. In this section, simulation modeling to perform precise numerical simulation is also presented. From the above discussion, the design procedure can be simplified: (1) one determines pump wavelengths with which a desired composite Raman gain can be obtained by adding in logarithmic scale individual Raman gain spectra shifted by the respective wavelength differences with adequate weight factors. And (2), one predicts how much power should be launched in order to realize the weight factors through precise numerical simulations. Section 5 verifies the superposition rule and the effect of pump-to-pump energy transfer by comparing a measured Raman gain with a superposed one. The agreement of two gain profiles shows that the multi-wavelength pumped Raman gain profile contains only the individual gain profiles created by the respective pump wavelengths. Section 6 concludes this paper.