Songbai He

Design of Broadband High-Efficiency Power Amplifiers Based on a Series of Continuous Modes

In this letter, a series of continuous modes for designing broadband high-efficiency power amplifiers (PAs) are proposed, which extend the continuous mode concept. The impedance solutions space based on these modes offer a greater freedom for realizing broadband high-efficiency PAs. To verify this theory, a high-efficiency PA over a 54.5% bandwidth from 1.6 to 2.8 GHz is designed. The simulated results show that the fundamental impedances in this PA are found to be in good agreement with the calculated ones. Moreover, this PA delivers average output power of 14.2 W with an average drain efficiency of 75.7% in the target band.

A New Distributed Parameter Broadband Matching Method for Power Amplifier via Real Frequency Technique

A general matching method is presented in this paper for broadband power amplifier (PA) design. A novel cost function is proposed for the real frequency technique (RFT), which could straightforwardly describe PA optimal impedance along with frequency change. The new function is also developed to design a broadband transformer for the PA output matching network (MN). Based on Richard transformation, a commensurate transmission line is deployed so that the PA matching could be convenient expressed by a real positive function. More important is that the function could be directly implemented with a distributed MN through synthesis theory. Therefore, this method is practical for computer-aided design and has less calculation amount with new function for the RFT. To verify the method, a step-by-step design of a broadband PA is given. For large signals, power gain is 14.2-16.8 dB across 0.9-2.8 GHz, while output power is around 39.5 dBm. The maximum power-added efficiency is from 52.2% to 85.1%.

A Post-Matching Doherty Power Amplifier Employing Low-Order Impedance Inverters for Broadband Applications

This paper presents a modified Doherty configuration with extended bandwidth. The narrow band feature of the conventional Doherty amplifier is discussed in the view of the broadband matching. To extend the bandwidth, the post-matching architecture is employed in the proposed design. Meanwhile, broadband low-order impedance inverters are adopted to replace the quarter-wavelength transmission lines. Low-pass filter topologies are used to realize both the post matching network and the impedance inverters. A modified Doherty Power amplifier was designed and fabricated based on commercial GaN HEMT devices to validate the broadband characteristics of this configuration. The 6-dB backoff efficiencies of 47%-57% are obtained from 1.7 to 2.6 GHz (41.9% fractional bandwidth) and the measured maximum output power ranges from 44.9 to 46.3 dBm in the designed band. In particular, more than 40% efficiencies are measured at 10-dB backoff throughout the operation band.

High-Efficiency Single-Ended Class-

In this paper, a single-ended class-E/F2 amplifier with a finite dc feed (FDC) inductor is proposed. In comparison to the other types of class-E amplifiers, a second harmonic parallel resonator at the drain node and an FDC feed inductor are its distinguished characteristics. The optimum operations for theoretical 100% drain efficiency are analyzed and simulated to show the performance improvements of this configuration on power output capability, maximum frequency, and load resistance compared to some previously published results. Design equations and parameters are given in lookup tables using numerical results. An example amplifier is given as a quick design guide, and from the measured results it offers 2.36-W output power, 86.6% drain efficiency, and 19.7-dB gain at 61.44 MHz.

{\hbox{E/F}}_{2}

In this paper, the effects of limited drain current and transistors on resistance on the performance of an LDMOS inverse class-E power amplifier (PA) are analyzed using a simplified transistor model of piecewise linear dc I-V curves. The minimal magnitude of driving signal, the maximal voltage gain, and the maximal output power of an inverse class-E PA can be defined with the maximal drain kept. The theoretical and simulated results of amplifier performance, such as drain efficiency and output voltage, are compared to verify the analysis, and the nonlinear relation among the drain dc supply voltage, input/output voltage, and phase of an inverse class-E PA caused by limited drain current are presented. The effects on the amplifier performance are further verified by the measured results of a 945-MHz transmission-line inverse class-E amplifier in comparison with the corresponding theoretical and simulated results.

Power Amplifier With Finite DC Feed Inductor

This paper reports on a modified class-E amplifier with a tuned series-parallel resonance network. This configuration introduces two additional resonance frequencies. The design equations required to determine the optimum operations are analyzed in detail by introducing three additional boundary conditions. compared to the conventional class-E amplifier, the numerical results show that the improvements on load resistance, maximum transistor current, power output capability, and maximum frequency can be obtained by properly selecting the resonance frequencies of the tuned network. Comparisons between simulations and measurements of an experimental circuit of the new configuration are drawn to validate the feasibility. The drain efficiency of 81.77%, power-added efficiency of 79.58%, and output power of 32.71 dBm (1.866 W) at 250 MHz are measured.

The Effects of Limited Drain Current and On Resistance on the Performance of an LDMOS Inverse Class-E Power Amplifier

In this letter, a broadband linear and efficient power amplifier for base-stations in long-term evolution (LTE) applications is designed, fabricated, and experimentally verified, employing Crees CGH40010F GaN HEMT. A novel method of baseband, fundamental and harmonic impedances control is used to provide high linearity and efficiency across a broad bandwidth. When producing a two-tone carrier-to-intermodulation ratio (C/I) of 30 dBc, the circuit has demonstrated a two-tone power added efficiency (PAE) between 45%-60% across the frequency range from 1.6 to 2.6 GHz while delivering 36.0-38.5 dBm average output power. For a single-carrier 20 MHz LTE signal with a peak-to-average ratio (PAR) of 6.5 dB, a measured high PAE of 40%-55% can be achieved at an average output power of 35.3-37.5 dBm with an adjacent channel leakage ratio (ACLR) of about -30 dBc from 1.6 to 2.6 GHz.

Performance Study of a Class-E Power Amplifier With Tuned Series-Parallel Resonance Network

In this letter, the design of a broadband asymmetric Doherty power amplifier (ADPA) with an 800 MHz (41% fractional) bandwidth is presented. The post-matching structure and low-order impedance transformation networks (ITN) are employed to achieve the broadband performance. Meanwhile, different drain biases on the main and peaking devices are used to run the asymmetric operation. The proposed ADPA shows high-efficiency performance at 8-9 dB output power back-off (OBO) throughout the whole 800 MHz band. The ADPA has been designed and implemented using commercial GaN HEMTs to validate the OBO and broadband characteristics. Maximum output power ranges from 43.7 to 45.2 dBm, 50.4%-56.2% efficiencies at 8-9 dB OBO are measured from 1.55 to 2.35 GHz.

Design of Broadband Linear and Efficient Power Amplifier for Long-Term Evolution Applications

In this letter, the bandwidth of the series of continuous modes (SCMs) power amplifiers (PAs) is extended. The SCMs are composed of a series of continuous working modes between Class-B/J and Class-F continuums. The second harmonic load of the series of continuums is purely reactive. By introducing resistive part to the purely reactive second harmonic load of the series of continuous modes, the operation bandwidth of power amplifiers is expanded. A broadband PA working across 0.8-3.05 GHz (117% bandwidth) is simulated and fabricated. Experimental results show that the drain efficiencies in interesting band are 57.4%-79%. The fabricated PA can deliver output power of 10.1-20.7 W.

Design of a Post-Matching Asymmetric Doherty Power Amplifier for Broadband Applications

A methodology for designing concurrent dual-band high efficiency power amplifiers (PAs) is presented in this letter. Load-pull simulations based on active device model are performed in two different bands to find the optimal required impedance conditions. A novel matching network with up to third order harmonic control is proposed to realize the high-efficiency mode matching in the two designed bands. A 1.9/2.6 GHz GaN PA is then designed to verify this method. The realized dual-band PA delivers above 10 W output power with more than 74% drain efficiency in the both operation bands.