An X-Band 100 W Gan Hemt Power Amplifier Using a Hybrid Switching Method for Fast Pulse Switching

Abstract

Abstract-This paper presents a new hybrid switching technique for enhanced pulsemode solid-state power amplifiers (SSPAs). In the proposed technique, pulse timing for bias stabilization is effectively decoupled from pulse amplification. The decoupling allows fast pulse switching by reducing the pulse width and increasing the pulse repetition frequency (PRF). The new switching method is applied to an X-band SSPA using GaN HEMT. The advantage of the proposed method is demonstrated by its excellent pulse characteristic. The proposed technique achieves a fast PRF of 100 kHz and a narrow pulse width of 1 µsec. The measured rise/fall time(RFT) is 12.5/11.1 nsec, which is more than four times less than that of previous works. In addition, an excellent pulse droop of 0.43 dB is achieved with an output power of 51.3 dBm at 9.9 GHz. The fabricated SSPA shows a maximum output power of 135 W, a small signal gain of 47 dB, and power added efficiency (PAE) of 28.2% at 9.9 GHz. These results show that the proposed pulse switching technique provides a promising solution for SSPAs using a high-power GaN HEMT.

A Simple and Universal Measurement Method for the Efficiency of Pulsed RF Power Amplifiers

“…2 shows a common bias and RF waveform. To avoid the influence of the DC bias on output pulse shape, the RF pulse signal is amplified after the DC bias is stabilized [7], [13]. In addition to the bias stability period, the DC bias pulse contains a guard time, including risetime, falltime and ringing time.…”

“…The RF circuit is composed of power transistors, RF chokes, DC blockers, isolators, etc. [7]. I D is the internal drain current flowing from the DC circuit into the RF circuit.…”

“…In addition, the conductor between the PA and drain bias switching circuit is always a planar circuit, such as a microstrip line. Current clamps cannot be easily mounted in such circuits, as shown in [7] and [14].…”

“…4. Pulse modulation is performed using an external RF switch, and the PA subsequently amplifies the modulated signal [7]. The bias voltage of the PA remains the same.…”

“…The application space includes wireless communication systems, radar, RF heating, jamming, imaging, and miniature DC-DC converters [1]. Much literature shows that PAs can be classified into two types: continuous wave (CW) PAs [2]- [4] and pulsed PAs [5]- [7]. Compared with CW PAs, pulsed PAs offer higher efficiency and are important for reducing size, weight and thermal stress [5].…”