Power transistors have typically traded performance for instantaneous bandwidth. Most devices show a huge drop in output power, gain, and efficiency when switching from relatively narrowband applications to circuits with wide instantaneous bandwidth, such as with pulsed RF signals. The new series of PowerBand discrete power transistors from TriQuint Semiconductor have been designed to be the exception to this rule, with excellent performance whether used in narrowband or wideband applications. These robust transistors are well suited for systems using either continuous-wave (CW) or pulsed and modulated signals, including radar, electronic-warfare (EW), and wireless communications systems.
The new line of PowerBand discrete power transistors currently includes six power transistors. As evidence of the flexibility of the PowerBand approach, the new transistors are based on two different device processes: silicon lateral diffused metal oxide semiconductor (LDMOS) and gallium arsenide (GaAs) pseudomorphic high-electron-mobility-transistor (pHEMT) technologies. The transistor covers a total frequency range of 500 MHz to 3 GHz with as much as 50 W output power at 1-dB compression at 2 GHz.
According to TriQuint President and Chief Executive Officer (CEO) Ralph Quinsey, “PowerBand changes the wireless equation, creating an opportunity to save a tremendous amount of space, cost, and energy. Because PowerBand efficiently delivers high power across unprecedented bandwidth, an RF design may require only one transistor line-up instead of several. This fact directly impacts the bill of materials and size of end user products by substantially reducing space dedicated to RF.”
Bill McCalpin, PowerBand Co-Inventor and General Manager, TriQuint Colorado Design Center, adds that “the incredible performance of PowerBand is the first thing that evaluating engineers recognize as truly outstanding. A traditional high-power RF transistor is designed to operate across a narrow frequency range, such as 2.53 to 2.65 GHz. Within that range it delivers power relatively efficiently. But as bandwidth increases, performance falls. PowerBand is totally different in its ability to deliver high power and high efficiency performance across a much wider frequency range, from 500 MHz to 3 GHz.”
High efficiency results in less heat generated by high-power RF/microwave transmitters, and less complexity and cost in controlling and dissipating the heat that is generated. In mobile devices, higher efficiency results in longer operating time on a battery and less heat generated in portable systems. Although the PowerBand technology has been applied to silicon LDMOS and GaAs pHEMT processes for the first set of power transistors, it is also applicable to other high-power device technologies, such as processes based on silicon carbide (SiC) and gallium nitride (GaN) wafers.
