Investigation of class-B/J continuous modes in broadband GaN power amplifiers

High efficiency two-stage GaN power amplifier with improved linearity

“…This allows the power amplifier in Class J/J* to maintain the same efficiency as Class B (78.5%), but allows for a larger design space. The following equations show the impedance termination of a Class J amplifier [9].…”

“…Through further analysis [10], it has been concluded that the design space for a Class B/J power amplifier would be larger than that of its counterpart, a Class B amplifier. In turn, the bandwidth of the amplifier is also improved if the harmonic impedances are chosen appropriately [9]. Another advantage to Class J/J* classes of operation is that they allow for the fundamental wave-form to be shaped appropriately such that maximum efficiency can be achieved.…”

Efficiency enhancement by employing the transistor nonlinear capacitors effects in a 6W hybrid X-band Class-J power amplifier

“…Employing the efficiency enhancement methods, which can effectively reduce the transistor power dissipation and thus, increase the reliability and median lifetime of the device, is essential for high power applications. Several topologies have been proposed for realization of high efficiency PAs . Reduced conduction angle PAs such as Class‐C PA, can provide high efficiency but they do not have sufficient output power and suffer from nonlinearity problems.…”

“…Several topologies have been proposed for realization of high efficiency PAs. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] Reduced conduction angle PAs 18 such as Class-C PA, can provide high efficiency but they do not have sufficient output power and suffer from nonlinearity problems.…”

“…The switching PAs such as Class-E and Class-D are well known for their ability to increase the efficiency; however, they cannot easily be realized at X-band frequencies. 19,20 In harmonic tuned PAs, [21][22][23][24][25][26][27][28][29][30][31] accurate shaping of the transistor drain voltage and drain current minimize the dissipated power in transistor. In Class-F PA designs, using a large number of harmonics, the drain voltage and drain current are shaped as a square and half-wave sinusoidal waveforms, respectively.…”