Improved Three-Stage Doherty Amplifier Design With Impedance Compensation in Load Combiner for Broadband Applications

IEEE Trans. Circuits Syst. I

et al. 2020

A novel Doherty power amplifier (DPA) architecture with extended bandwidth is presented in this paper. A modified load modulation network is introduced to provide impedance condition required by the Doherty operation in a wide frequency range. Analytical parameter solutions of the proposed load modulation network and the related load modulation process are presented. A DPA with 2.80-3.55 GHz bandwidth utilizing commercial GaN transistors is implemented. The fabricated DPA attains a measured 9.3-11.1 gain and 43.0-45.0 dBm saturated power. 50.0-60.6% and 66-78% drain efficiency is obtained at 6 dB output power back-off and saturation throughout the designed band, respectively. Moreover, the back-off drain efficiencies are higher than 55% within 700 MHz bandwidth. When driven by a 6-carrier 120 MHz OFDM signal with 7.0 dB peak to average power ratio, the proposed DPA achieves adjacent channel leakage ratio of better than-50 dBc after digital pre-distortion (DPD) at 3.20 GHz with average efficiency of 53.3%.

Section: Introductionmentioning

confidence: 99%

Bandwidth Enhancement of Doherty Power Amplifier Using Modified Load Modulation Network

IEEE Trans. Circuits Syst. I

et al. 2020

“…Among them, DPA has become one of the most widely used PA architectures in wireless cellular base stations because of its low complexity and high reliability. To support multi-band/multi-mode operation and to accommodate wide signal bandwidth requirement, several bandwidth extension techniques for DPAs have been introduced, such as continuous mode technique [1]- [3], impedance compensation [4], [5], complex combining loads [6] and postmatching structure [7]- [9]. Most wideband DPAs reported to date focus on the symmetric structure [1]- [4], [6]- [12], limiting the efficiency performance at deep back-off region.…”

Section: Introductionmentioning

confidence: 99%

“…Compared with other PA architectures that can achieve a large high-efficiency range, such as asymmetrical or multistage Doherty PAs [5], [25], the design of the proposed SLMBA is easier due to the constant load condition at…”

Section: Introductionmentioning

confidence: 99%

Analysis and Design of Highly Efficient Wideband RF-Input Sequential Load Modulated Balanced Power Amplifier

IEEE Trans. Microwave Theory Techn.

et al. 2020

The analysis and design of an RF-input sequential load modulated balanced power amplifier (SLMBA) are presented in this paper. Unlike the existing LMBAs, in this new configuration, an over-driven class-B amplifier is used as the carrier amplifier while the balanced PA pair is biased in class-C mode to serve as the peaking amplifier. It is illustrated that the sequential operation greatly extends the high efficiency power range and enables the proposed SLMBA to achieve high backoff efficiency across a wide bandwidth. An RF-input SLMBA at 3.05-3.55 GHz band using commercial GaN transistors is designed and implemented to validate the proposed architecture. The fabricated SLMBA attains a measured 9.5-10.3 dB gain and 42.3-43.7 dBm saturated power. Drain efficiency of 50.9-64.9/46.8-60.7/43.2-51.4% is achieved at 6/8/10 dB output power back-off within the designed bandwidth. By changing the bias condition of the carrier device, higher than 49.1% drain efficiency can be obtained within 12.8 dB output power range at 3.3 GHz. When driven by a 40 MHz OFDM signal with 8 dB peak to average power ratio (PAPR), the proposed SLMBA achieves adjacent channel leakage ratio (ACLR) better than-25 dBc with an average efficiency of 63.2% without digital predistortion (DPD). When excited by a 10-carrier 200 MHz OFDM signal with 10 dB PAPR, the average efficiency can reach 48.2% and-43.9 dBc ACLR can be obtained after DPD.

“…In recent years, many efforts have been made to expand the frequency band coverage of DPAs. By introducing techniques such as continuous mode impedance [13]- [15], post-matching architecture [16]- [19], integrated compensating reactance [20], [21] and complex combing loads [22]- [24], bandwidth of DPAs has been greatly extended. However, when the required operation bands are separated by more than one octave, it is still difficult to cover them with Doherty operation [25], [26].…”

Section: Introductionmentioning

confidence: 99%

Multiband Dual-Mode Doherty Power Amplifier Employing Phase Periodic Matching Network and Reciprocal Gate Bias for 5G Applications

IEEE Trans. Microwave Theory Techn.

Dai

et al. 2020

This paper presents a novel method to design the multi-band Doherty power amplifier (DPA). It is illustrated that phase periodic matching networks (PPMNs) can be used as multi-band impedance inverters, offset elements and phase compensators to realize multi-band DPAs. Moreover, the number of Doherty operation bands can be further increased by employing the reciprocal gate biases. A 6-band dual-mode DPA with 1.8-2.2/3.9-4.3 GHz operation bands in Mode I and 1.52-1.72/2.38-2.53/3.67-3.82/4.53-4.68 GHz operation bands in Mode II using commercial GaN transistors is designed and implemented to validate the proposed method. The fabricated DPA achieves 8.7-13.5 dB gain and 39.6-41.5 dBm peak output power at all the designed bands. Drain efficiency of 49.2%-54.5% and 42.2%-56.7% is measured at 6 dB output back-off in Mode I and Mode II, respectively. When stimulated by a 5-carrier 100 MHz OFDM signal with 7.7 dB peak to average power ratio (PAPR), adjacent channel power ratio (ACPR) of better than-48.9 dBc can be obtained by the proposed DPA after digital predistortion with 35.5%-50.1% average drain efficiency at 1.65/1.95/2.45/3.75/4.1/4.6 GHz, respectively.