High power time domain measurement system with active harmonic load-pull for high efficiency base station amplifier design

Abstract

A measurement system combining vector corrected waveform measurements with active harmonic load-pull extends, for the first time, real-time experimental waveform engineering up to the 30W power level. This novel harmonic load-pull approach is demonstrated on a 4W LDMOS device. A 20% increase in maximum output power to 4.7Watts without degrading gain and efficiency was realized.

A time-domain large-signal measurement setup

“…Again, both maxima are located close to each other; an optimum combination would be 2 ϭ 0°and 3 ϭ Ϫ120°, as shown in Figure 10. Further investigation of Figure 9 also shows that the dependence of 2 is higher than that of 3 . This is a result of Class B biasing, which generates-when not harmonically terminated-a half-sinusoidally-shaped waveform, thereby having ideally only even harmonics.…”

“…To overcome stability problems with active loops [2], an open-loop system with synchronized frequency generators was chosen. The use of generators also eliminates the need for frequency multipliers, filters, phase shifters, and attenuators in setups such as those in [3]. The only element which still needs to be realized according to measurement needs is the inevitable triplexer.…”

Using active IF load-pull to investigate electrical base-band induced memory effects in high-power LDMOS transistors

“…Active harmonic load-pull is a relatively simple concept and is effective in allowing the presentation of specific loads to specific frequency components generated by a device [4]. Presenting constant RF loads actively across wide modulation bandwidths is however extremely difficult in comparison, and fraught with complexity.…”

Medición de las formas de onda en la caracterización de dispositivos de microondas: impacto en el diseño de amplificadores de potencia

“…The frequency dependent optimum terminations can be determined by means of experimental characterization of the devices, in particular using load pull systems that measure the several figures of merit of the device (e.g., output power, efficiency, gain) while varying its load condition [3,4,5]. Enabling the observation of the voltage and current waveforms on the device allows designers to reach an even deeper understanding of the working mechanisms of the device, and permit a better relation between the power amplifier theory and the real device operation.…”