Shirt Fun Ooi

High-efficiency power amplifier design including input harmonic termination

This letter presents the design of a high-efficiency Class-F power amplifier in pseudomorphic high electron mobility transistor technology using a novel load-pull/source-pull simulation-based approach. The second harmonic input termination is shown to have a critical influence on performance, which is justified by the shape of the simulated waveforms. Experimental validation is carried out on a 2-GHz practical circuit using a medium-power packaged device. Two cases are compared both theoretically and experimentally: for the best and worst case second harmonic input terminations, 76% and 42% saturated power-added efficiency are measured, respectively. In addition, the worst case termination degrades the saturated C/I3 by 7.5dB.

High efficiency class-F power amplifier design

In this paper, a high efficiency, low voltage, class-F power amplifier (PA) is described. The effect of different output harmonic terminations on the power-added efficiency (PAE) of the PA has also been analysed. A medium power PHEMT PA, operating at 900 MHz, is designed and measured. A peak PAE of 71.4% with 22 dBm output power (P/sub out/) and 14 dB power gain (G/sub p/) is achieved at a very low drain voltage (V/sub ds/) of 3 V. A PAE above 60% has been achieved over a bandwidth of 13%.

Efficient Coupling Impedance Formulas for the Right-angled Isosceles Triangular Patch for Use in Segmentation Analysis

An explicit and computationally efficient coupling impedance formula for the coupling between two perimeter ports on a perpendicular side of a right-angled isosceles triangular patch microstrip segment is derived. Based on coplanar circuit analysis an initial impedance formula is obtained in terms of a single and a double infinite series expression. Application of closed forms for the series reduces the single series to a closed form, and, the double series reduces to a single series. The new computationally efficient coupling formula is verified by comparison with simulation based on full wave analysis, and, practical measurement

Microwave class-F power amplifier design including input harmonic terminations

In this paper, we present the design of a high-efficiency class-F power amplifier in pHEMT technology using a novel load-pull/source-pull simulation-based approach. The 2nd harmonic input termination is shown to have a critical influence on PA performances, which is justified by the shape of the simulated waveforms. Experimental validation is carried out on a 2 GHz practical circuit using a medium-power packaged device. Two cases are compared both theoretically and experimentally: for the best and worst case 2nd harmonic input terminations, 76% and 42% saturated PAE are measured, respectively. The worst case termination degrades the saturated C/I3 by 7.5 dB.

Design of a circular polarized nearly square microstrip patch antenna with offset feed

This paper presents the design of a circular polarized nearly square patch antenna using an offset microstrip feed. By using an offset feed instead of the normal corner feed, it is shown that the area of the perturbation segment must increase in order to maintain circular polarization. Consequently, the effect of manufacturing errors on the axial ratio is reduced. Using a fixed offset feed position, the dimensions of the antenna are uniquely obtained. The antenna is matched using a simple matching network consisting of a short length of microstrip line. A matched antenna was designed to operate at 2.45 GHz, and an axial ratio of <0.5 dB with a return loss of >20 dB was obtained experimentally. The predicted, simulated and practical results are shown to be in good agreement.