Raymond S. Pengelly

Parameter extraction for large signal noise models and simulation of noise in large signal circuits like mixers and oscillators

This paper shows how to obtain an equivalent circuit model for bipolar transistors and FEITs to generate a bias-dependent model. The bias-dependent model is required as a seed to obtain starting values for a large signal model. Particularly in the case of calculating noise under large signal conditions, the bias-dependent noise parameters for both bipolar transistors and FETs have to be obtained. For verification purposes, these methods have been implemented in the nonlinear circuit simulator, Microwave Harmonica. We have employed double balanced diode mixers, both active and passive (switching) FET mixers as well as a variety of oscillators to show that the nonlinear noise analysis capabilities are verified in these applications.

Doherty's Legacy: A History of the Doherty Power Amplifier from 1936 to the Present Day

Eighty years ago, William Doherty invented a PA architecture that has played-and will continue to play-an important role in the development of energy-efficient radio transmitters for a variety of wireless communication applications. Although the original concept is still equally valid, the development of new semiconductor processes and digital signal processing techniques has served as a basis for an evolution of the DPA topology into the 21st century. The need for energy-efficient power amplification will be further emphasized in future wireless systems (5G and beyond) through the projected exploration of dense-antenna arrays and millimeter-wave frequencies. Recent developments of the Doherty concept make it one of the most attractive candidates for realizing energy-efficient wireless systems into the future.

Design of GaN HEMT Transistor Based Amplifiers for 5 - 6 GHz WiMAX Applications

2.5 and 5 Watt average power (15 and 30 Watt peak power) GaN HEMT amplifiers for WiMAX signal protocols have been designed and fabricated for use in the 5.5 to 5.8 GHz band. The 2.5 Watt PA produces 11 dB of gain and the 5 Watt PA produces 10 dB of gain with EVMs less than 2.5% at the respective average power with drain efficiencies greater than 26% at average power. A design methodology for optimizing linear performance is described for these two transistors and resultant amplifiers.

Inverse Class-F Design Using Dynamic Loadline GaN HEMT Models to Help Designers Optimize PA Efficiency [Application Notes]

Simulation of power amplifiers (PAs) for modern wireless base station and small cell systems is an essential part of the design process. At a cell site, the PA consumes the bulk of the dc power, generates the most heat, and thus represents the greatest operational cost. Maximum PA efficiency is a necessity to manage these costs, which is a sizeable challenge in a PA that also must be highly linear to support the complex multilevel modulation types and wide bandwidths used for current and developing wireless transmission standards. Accurate simulation allows the PA designer to meet these challenges by exploring the available design options and then optimizing the circuit that is selected for the application.

The Doherty power amplifier

The Doherty power amplifier (DPA) architecture, in various formats using different technologies, has been a very popular means of providing high conversion efficiencies from raw electrical power to sophisticated modulated RF and microwave signals ever since the requirements for very high power amplitude modulated (AM) radio transmitters in the mid-1930s. This paper covers not only the “original stories” of high power tube-based Doherty power amplifiers for those early AM transmitters, but also provides many examples of implementations employing a range of modern semiconductor transistor and circuit technologies covering a wide range of power levels, modulation schemes and carrier frequencies.

Early GaAs FET monolithic microwave integrated circuit developments for radar applications at Plessey, UK

The early development of GaAs FET monolithic microwave integrated circuits (MMICs) for phased array radar applications at Plessey in the UK over the period of 1975 through 1989 is described. Following the introduction of a basic GaAs MMIC fabrication process in the early 1970’s at Plessey Central Research Laboratories (Caswell) and the characterization of distributed and lumped element components at Plessey Applied Research Laboratories (Roke Manor) a complete range of MMICs were designed and fabricated to be used in fully integrated transmit/receive modules in S-band.

A waveform engineered power amplifier design for envelope tracking

A novel load network design for limited harmonic manipulations to implement a transmission line waveform engineered radio frequency power amplifier for LTE applications is presented in this paper, with the target to achieve quasi-linear efficiency during power back-offs with harmonic iteration. The topology selection was based on accurate large signal modeling and simulation to obtain optimum microstrip line design controlling the 2nd and 3rd order harmonics at the transistor output terminal. The design was implemented using the Cree CGH40010F GaN HEMT at 2.14GHz. It provides a continuous wave (CW) drain efficiency of 73.7% at a saturated output power of 40.7dBm at a fixed 30V supply, but it was optimized for linearization with LTE 64QAM 20MHz modulated signal with a power-added efficiency (PAE) of 42.7% at an average output power of 34.9dBm with linearity meeting 3GPP specifications, as well as envelope tracking with almost 70% power added efficiency from the same PA.