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A high-efficiency push-pull power amplifier has been designed and measured across a bandwidth of 250MHz to 3.1GHz. The output power was 46dBm with a drain efficiency of above 45% between 700MHz and 2GHz, with a minimum output power of 43dBm across the entire band. In addition, a minimum of 60% drain efficiency and 11dB transducer gain was measured between 350MHz and 1GHz. The design was realized using...
A novel, highly efficient and broadband RF power amplifier (PA) operating in “continuous class-F” mode has been realized for first time. The introduction and experimental verification of this new PA mode demonstrates that it is possible to maintain expected output performance, both in terms of efficiency and power, over a very wide bandwidth. Using recently established continuous class-F theory, an...
A new methodology is presented for designing baluns exhibiting multi-decade bandwidths at microwave frequencies. Simulations show that resistors terminating the outer transmission line suppress the half-wavelength resonance and greatly extend the bandwidth. Using linear measurements at microwave frequencies, ferrite beads have been shown to behave as resistors with a small reactance, suitable for...
This paper demonstrates how the linearity performance of a 10W GaN HEMT can be dramatically improved by actively engineering the baseband impedance environment around the device. An important refinement to existing active load-pull measurement capability is proposed that allows the precise and independent control of all significant baseband and RF components that result from the amplification of a...
This paper presents a hybrid (passive & active) power amplifier concept for a wideband high drain efficiency power amplifier design. The proposed design integrates for the first time a dual-band PA with an active second harmonic injection to achieve high efficiency across a continuous wideband frequency range of two octaves. The design utilizes a resistively loaded class B at the lower frequencies...
This paper introduces a novel approach for the realization of wide band (>octave) high-efficiency (>95%) high Power Amplifiers (PAs). The proposed concept utilizes active harmonic injection to achieve the appropriate waveform shaping of the voltage/current waveforms necessary to deliver simultaneously both high power and high efficiency operation. The new PA structure thus consists of two parallel...
This paper presents a rigorous way to quantify the role played by higher baseband impedances in determining baseband electrical memory effects observed in power transistors under two-carrier excitation. These effects typically appear not only as asymmetrical distortion terms in the frequency domain, but also more reliably as a recognizeable hysteresis or looping in the dynamic transfer characteristics...
Results from a fully implemented class-J RFPA (RF power amplifier) are presented for the first time, which demonstrate this mode's high efficiency potential across a substantial bandwidth. Using a commercially available 10W GaN (gallium nitride) HEMT device, and the high power waveform measurement and active load-pull capability at Cardiff University, class-J operation has demonstrated drain efficiencies...
Memory effects are generally attributable to thermal, electrical, packaging and/ or surface effects. This behaviour in turn impacts overall linearity and importantly the suitability of a power amplifier (PA) to linearisation through pre-distortion. It is assumed that electrical memory introduced by the low-frequency baseband impedance environments associated with the power amplifier bias insertion...
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