A new power amplifier topology with series biasing and power combining of transistors

Millimeter-Wave Series Power Combining Using Sub-Quarter-Wavelength Baluns

“…Power can also be combined [11]- [14] by using a combination of direct :1 series and :1 parallel connections ( Fig. 2(a)).…”

“…With the transformer combiners, the challenges are low inductor Q, significant parasitic series inductance and inter-winding capacitance, and port imbalances. Power can also be combined using direct transistor series-connection with local negative feedback [11]- [14]. Series connection enables low-loss power-combining in a small die; with this technique the challenges are maintaining a uniform voltage distribution and unity current gain, so that all transistors compress at the same RF drive level, as is necessary for high linearity and high efficiency.…”

Design and Analysis of Stacked Power Amplifier in Series-Input and Series-Output Configuration

“…The smallsignal collector currents of each cell will also be identical so the collector-emitter capacitance and early resistance can be considered as a series connection with a total impedance of driven by a common emitter current. The total input voltage will be the sum of the voltages across each transformer, and the output voltage is ( 5) From ( 6) and ( 8), the voltage gain is (6) The input impedance is (7) By applying a test voltage across the output and setting the input to short, the output impedance can be calculated. The transformers are assumed not stored with any energy, and the output impedance is simply (8) Defining the coupling factor of the transformer as (9) the voltage gain of ( 9) can be conveniently expressed as (10) From the analysis flow and the conclusions of ( 6)-( 10), the series-input and series-output transformer coupled stack can be interpreted as a stack of common emitter devices with the same characteristics operating in unison.…”

“…Other series configurations are less common, but also can be seen in the literature. A three-device totem pole configuration, which is like a triple-cascode configuration, demonstrated a 36-dBm output power at 4 GHz [7]. Another method connects all the devices' drains and sources in series, but the inputs and outputs are still connected to the devices in parallel, with proof-of-concept designs in -and -band [8].…”

Optimization of InP DHBT stacked-transistors for millimeter-wave power amplifiers

“…Collector-emitter breakdown is avoided by making the overall output voltage be equally divided among all the devices. This architecture has been successfully deployed at RF and microwave frequencies since its conception a couple of decades ago [3–9], showing promising performances in terms of output power, gain, and efficiency. More recently, many research efforts have been exerted to extend the stacked-transistor concept at higher frequencies and into the millimeter-wave range [10–15].…”