10W ultra-broadband power amplifier

Abstract

We report the design and performance of an ultra-broadband power amplifier. It achieves 10 Watts output power with 21dB ± 1.5dB gain from 20 MHz to 3000 MHz. At lower frequencies from 20 to 1000 MHz the output power is 15 Watts with 22% efficiency. To achieve this performance, we employ a new design concept to control the device impedance and the power combiner impedance to be naturally 50 Ohms, such that no impedance matching is needed. Also, we developed a broadband microwave balun as a push-pull power combiner, which doubles as an impedance transformer. We believe the combination of output power, bandwidth and efficiency is the best reported to date.Index Terms -Power amplifiers, power combiners, broadband amplifiers, broadband balun, HIFET amplifiers.

Design of 600-W Low-Loss Ultra-Wideband Ferriteless Balun

“…Marchand compensated transmission line concepts [5]- [12] are widely used to design wide bandwidth baluns on printed circuit boards. Other techniques including parallel and serial-connected coaxial lines [13]- [18], ferrite coupled-coil lines [19], [20] and coaxial lines loaded with bulky ferrite cores [21] have been used to extend the balun bandwidth. Phelan [13] and Robert [14] connected a single coaxial section with another short parallel solid rod and serial coaxial transmission line to obtain a good input matching over two widely-separated frequencies.…”

“…Their sizes become excessively large at low frequencies. To operate at low frequencies down to a few MHz's, a typical coaxial balun loads its λ/4 coaxial line with ferrite beads that enhance the inductance per unit length, consequently increasing the characteristic impedance of the coaxial transmission line [21]- [23]. Coupled-wire baluns are formed by winding a coaxial cable in N turns to enhance inductance by a factor N 2 , resulting in a very large balun structure [19], [20].…”

“…In these baluns, a ferrite core with high permeability is used with a conventional quarter-wavelength transmission line to convert a single-ended signal into a balanced one. The power handling capabilities of the ferrite baluns [21]- [23] are limited by the ferrite materials that suffer high losses and magnetic saturation [25]. The ferrite, dielectric and conductive losses produce internal heat that contributes to the circuit breakdown of the coaxial baluns [24], [26], [27].…”

23:1 Bandwidth ratio quasi‐lumped component balun on a multilayer organic substrate

“…Therefore, planar Marchand baluns typically have a bandwidth ratio of less than 10 to 1 [10][11][12][13][14][15][16][17][18]. The balun in [20] has a wide bandwidth from 1 MHz to 3 GHz, but it is designed using three ferrite cores that result in a large and bulky component. Coplanar waveguide (CPW) baluns [21,22] typically have a bandwidth ratio larger than 10 to 1.…”

A 5W ultra-broadband power amplifier using silicon LDMOSFETs

“…To alleviate the problems, addressed above a push-pull configuration and a negative feedback network have been adopted for the design [3], [4]. A broadband impedance transformer has been implemented for the input and output baluns based on a coaxial transmission line and a toroidal ferrite core.…”