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.

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%.

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.

The hybrid continuous modes are constituted by a continuum of power amplifier (PA) modes between class-J and continuous class-F. In this letter, a phase shift parameter is introduced in the voltage waveform formula of the hybrid continuous modes to generate complex fundamental and harmonic load impedances, leading to a further extension on the operation bandwidth. Based on the proposed theory, a gallium nitride PA is designed and fabricated over the frequency band of 1.2-3.6 GHz. The measured results show a 60%-72% drain efficiency at a saturated power of 40-42.2 dBm. In addition, when driven by a 20-MHz long-term evolution signal with a peak-to-average power ratio of 7.4 dB, the proposed PA obtains an adjacent channel leakage ratio of -35 dBc at an average output power of 35 dBm at 2.3 GHz.

A method enabling the codesign of a high-efficiency power amplifier (PA) and a ring-resonator microstrip bandpass filter is proposed in this paper. Even-odd-mode analysis and a series of continuous modes (SCMs) are combined to realize broadband or multiband impedance matching as well as the suppression of undesired signals. The proposed codesign method can achieve both broadband and multiband frequency responses, and the designed component is relatively easy to analyze and fabricate due to its microstrip structure. For verification, a broadband and triband PA-filter components are designed and fabricated separately. The first component operates across 0.8-3.2 GHz (120%) with 39.7-42.9-dBm maximum output power and 57%-74% drain efficiency (DE). The second component, which has three passbands, covers several commercial frequencies with a measured output power of 39.6-41.3 dBm and DE from 62% to 68%. When these two components are driven by a 20-MHz long-term evolution signal with a peak-to-average power ratio of 6.2 dB, adjacent channel leakage ratios from -26.4 to -33.8 dBc and from -29.4 to -33.1 dBc are measured, respectively.

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.