Weimin Shi

Design of Broadband Power Amplifiers Based on Resistive-Reactive Series of Continuous Modes

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.

A Series of Inverse Continuous Modes for Designing Broadband Power Amplifiers

In this letter, a series of inverse continuous modes for implementing highly efficient broadband power amplifiers (PAs) are proposed. These series of inverse continuous modes are extended from continuous Class-F-1 mode. A broadband PA, which operates across 2.4-3.9 GHz, is designed based on the series of inverse continuous modes (SICMs). The experimental results show that this power amplifier achieve drain efficiency of 62.2%-74.7% in the whole interesting band. The average output power of this designed PA is 11.9 W with average drain efficiency of 68.1%.

Extend the Class-B to Class-J Continuum Mode by Adding Arbitrary Harmonic Voltage Elements

An extended Class-B to Class-J continuum mode is presented and a power amplifier(PA) based on this theory is realized in this paper. The enhanced voltage waveform formulation, which gives multiple impedances solutions of the fundamental and harmonics for the target performance by adding the harmonic elements, has been described mathematically. Unlike conventional continuous Class-J mode, the optimal impedance solutions of the new mode can contain real and imaginary parts of arbitrary even harmonics. To verify this theory, a high-efficiency PA from 2.85-4.25 GHz is designed at the package plane. The measurement results illustrate that the fabricated PA outputs 11.7-15.8 W saturation power with drain efficiency(DE) of 58% to 78% and PAE of 54.5%-74% across the entire band. For a 5 MHz WCDMA signal with a peak-to-average ratio (PAR) of 8.6 dB, an adjacent channel leakage ratio (ACLR) of -31.5 to -38 dBc is measured at an average DE of 38%-48% when the output power (Pout) is 36 dBm from 2.85-4.25 GHz.

Broadband Continuous-Mode Doherty Power Amplifiers With Noninfinity Peaking Impedance

In this paper, a broadband continuous-mode Doherty power amplifier (CM-DPA) is realized taking advantage of the noninfinity output impedances of peaking stage. Specifically, the carrier PA of the designed DPA operates in a continuous class-J mode when the peaking PA is in the OFF-state, where the output impedance of the peaking PA has some influences on the carrier PA. When the peaking transistor is in the OFF-state, the load impedance variation of the carrier transistor versus noninfinity peaking impedance is presented in this contribution. The proposed method surmounts the back-off drain efficiency deterioration of DPAs at two side working bands through elaborately processing the noninfinity peaking impedance. This paper also presents a method to derive the required OFF-state output impedance of the peaking stage by the carrier PA in a symmetrical broadband DPA. A broadband CM-DPA working over 1.6–2.7 GHz (bandwidth of 51%) is designed and fabricated for interpreting our theories. The simulated load trajectory of the carrier transistor is in line with the design space of continuous class-J mode. Under continuous wave excitation, experimental results show the drain efficiencies of 46.5%–63.5% at 6-dB output back-off power levels and 56%–75.3% at peaking power levels. The maximum output power of this DPA is 43.8–45.2 dBm with a gain of 9.4–11.5 dB across the whole working band. Furthermore, a 20-MHz LTE modulated signal with a peak-to-average power ratio of 7.4 dB is also applied to the fabricated CM-DPA at 2.2 GHz. At an average output power of 37.5 dBm, measurement results show the adjacent channel power ratios of −30.2 and −50.1 dBc before and after digital predistortion, respectively.

A Semianalytical Matching Approach for Power Amplifier With Extended Chebyshev Function and Real Frequency Technique

In this paper, an extended Chebyshev function is proposed to adapt the matching condition of the power amplifier (PA) by introducing a new factor. A set of impedance functions can be directly calculated along with the variation of a new variable, and the first element extracted from the functions is distributed in a wide range. In addition, the impedance function whose first element is the closest to the output capacitance of the transistor can be easily read out and selected as the original matching network. The fundamental impedance of the selected function will be reached a good matching state, and the impedances out of band will be on the edge of Smith chart. To achieve better performances, the real frequency technique is applied to adjust the harmonic impedances preventing it from falling into the low-efficiency region. Two PAs with a relative bandwidth of 34% and 75% are implemented to validate the proposed approach.

The Influence of the Output Impedances of Peaking Power Amplifier on Broadband Doherty Amplifiers

The effect of the output impedance of peaking power amplifier (PA) on Doherty PAs (DPAs) is analyzed in this paper. In the design procedure of DPAs, the ideal case is that the output impedance of auxiliary PA is infinite at output power back-off (OPBO) level. However, it is almost impossible to realize this perfect condition in broadband DPAs. Therefore, when the output impedance of peaking path deviates from infinity, some potential effects on DPAs must be produced. In this paper, these effects are explained at the internal plane of transistors. The conclusion is that, at different normalized frequencies, there are different optimal impedance regions for the output impedance of peaking stage. This means that the noninfinite output impedances of peaking stage can enhance the performances of broadband DPAs so long as they are elaborately processed. A 1.65–2.7-GHz (48% bandwidth) broadband DPA is designed considering the effects of peaking PA. The experimental results show that this DPA obtains a drain efficiency of 41%–59.6% at 6-dB OPBO levels and a drain efficiency of 55.8%–72.2% at saturation power levels. The maximum output power across the entire operating band is 43.1–45.2 dBm with a gain of 9.0–10.2 dB. Furthermore, the designed DPA achieves an adjacent channel leakage ratio of −45.8 dBc with an output power of 36.1 dBm at 2.0 GHz after digital predistortion when it is excited by 5-MHz WCDMA signal with a peaking-to-average power ratio of 8.6 dB.

A method for designing generalized continuous power amplifier

In this paper, a method for designing generalized continuous harmonic-tuned power amplifier (PA) is introduced. A more generalized continuum mode is presented by combining the resistive-reactive continuous Class-F mode and resistive-reactive continuous inverse Class-F mode. The strict harmonic impedances termination conditions are relaxed. Also, as the effect of the nonlinear capacitance, the design focus more on the fundamental impedances matching. And a broadband PA is designed based on this method. The output power is more than 12W with the gain over 11dB form 2.4 to 3.75 GHz. And the drain efficiency (DE) is from 66% to 71% across the design band.

Deign of broadband highly efficienct Doherty power amplifiers by using series of continuous modes

In this paper, the series of continuous working modes of power amplifier(PA) are introduced into Doherty PAs. The series of continuous modes contain the continuous working modes between Class-B/J and Class-F continuums. By judiciously optimizing the phase of carrier output matching network, the series of continuous working modes can be got by carrier PA at peaking output. A highly efficient broadband Doherty PA based on series of continuous modes is implemented with operation band over 1.65-2.4GHz. At 6dB power back-off and maximum output power, the drain efficiencies of this Doherty PA are 46%-57% and 60.12%-76.24%, respectively. The gain and output power characteristics of the DPA at saturation are 11.5-12.1dB and 43.55-45.1dBm, respectively.

Novel Unequal Dividing Power Divider With 50

In this letter a novel power divider (PD) structure with uniformed characteristic impedance lines and a fixed isolation resistor equal to source and load impedances has been proposed. Unlike traditional power dividers, the electrical lengths of the uniformed 50 Ω branches are the only parameters that need to be adjusted to achieve any required power division ratios, which makes it a flexible and adaptable layout for most desires. Arbitrary power division ratio, especially large dividing ratio that is difficult to achieve by conventional Wilkinson PD, can be obtained easily by applying the proposed structure. For verification, the measured results of a 2 : 1, a 4 : 1 and a 9 : 1 PDs operating at 3 GHz are shown in this letter.

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In this paper, we analyze the shortcomings of traditional Doherty power amplifier (DPA) structure and propose an improved load modulation structure; Improving back-off efficiency of Doherty amplifier by using pre-matching technology. Also, the linearity is improved by using the in-band error cancellation technique of the Doherty amplifier. We implemented a Doherty amplifier with Crees 10 W GaN HEMT transistor as carrier amplifier and peaking amplifier, respectively. At 3.5 GHz, saturated output power of the DPA is more than 43 dBm, saturated drain efficiency is greater than 75%; Under two-tone signal spacing by 5 MHz interval testing, drain efficiency of 6 dB back-off is greater than 50%, and IM3 is less than 30 dBc.