A flexible GaN MMIC enabling digital power amplifiers for the future wireless infrastructure

Heinrich

2019

Self Cite

This paper presents a fully digital transmitter chain from baseband to antenna, including a modulator, two truly digital (i.e. fully switched) microwave power amplifiers and a transmit/receive switch. Both, amplifier and switch monolithic microwave integrated circuits were implemented in a GaN HEMT process. The novel amplifier design provides greatly reduced complexity, needing only three voltage sources. Measurements were conducted using 5, 20, and 100 MHz wide baseband signals. Carrier frequencies cover the 900 and 2000 MHz bands. For the 5 MHz BB signal an ACLR of over 52 dB is reached, fulfilling the 3GPP specs for base station use while still maintaining a final-stage drain efficiency of 46% at 6.5 dB peak to average power ratio. Full-scale output power at 30 V supply voltage was measured to exceed 3 W at 80% drain efficiency. Further features of this digital amplifier approach include small form factor and frequency agility, making it an ideal candidate for software defined radio.

Section: Introductionmentioning

confidence: 92%

Highly compact GaN-based all-digital transmitter chain including SPDT T/Rx switch for massive MIMO applications

Huhn

Heinrich

2019

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“…The blocks at the input represent the driver stages. This topology is commonly used for voltage-mode class-D/S PAs [2,4]. The output network is composed of a reconstruction filter with L filt(A,B) and C filt and the load resistance R load .…”

Section: Digital Outphasing Pa Designmentioning

confidence: 99%

“…The ReCo at the FS transistors (V1/2 (A/B) in Fig. 2) is important for a low-loss design [8], since in the hard-switched case [4] remarkable capacitive switching losses occur. Effective output capacitances of used FS transistors are in total 1.4 pF.…”

Section: Optimizing Efficiency and Resonant Commutationmentioning

confidence: 99%

“…As a consequence, in the last years, increasing research efforts have been devoted to non-analog power amplifier (PA) realizations (e.g. [2][3][4]), paving the way to an all-digital transmitter chain shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

“…Future wireless communication standards will be based on very broadband signals with high peak-to-average power ratios (PAPR) in the 10-12 dB range. This is responsible for one of the most crucial problems of the digital PAs up to now, the significant degradation of efficiency at high power back-off (PBO) values [2,4]. The values achieved so far [5] are not fully competitive to analog concepts like Doherty [6] or envelope tracking [7].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

GaN digital microwave outphasing PA

Hoffmann

Flisgen

et al. 2020

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This paper presents a novel GaN-based digital outphasing power amplifier (PA) for the 800 MHz range. The PA reaches a maximum output power of 5.8 W at 30 V final-stage (FS) drain supply voltage. A novel output combiner circuit is used and efficiency is improved by resonant commutation of the FSs and optimized driver circuits for the two GaN push-pull FSs. 3D electromagnetic simulation of output network has been conducted to extract an equivalent circuit model and to access full information in terms of functionality and broadband impedance characteristics for optimized outphasing operation in the final design. Measured total efficiencies (ηtot) of 59 and 25% at 0 and 10 dB power back-off are achieved, respectively, fitting the simulation quite well. The proposed digital outphasing module is a promising candidate for fully digitized base-station architectures in future wireless communications.

An efficient W-band InP DHBT digital power amplifier

Hossain

Stoppel

et al. 2017

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This paper presents for the first time high-efficiency W-band power amplifiers (PAs), the design of which follows the digital PA (DPA) design concept. Two DPAs with different output networks have been realized: a single-band version (S-DPA) for 95 GHz and a dual-band design (D-DPA) for signal frequencies fSof 68 GHz (first band) and 76 GHz (second band), respectively. The PAs are realized as monolithic microwave-integrated circuits (MMICs) in a 0.8 μm InP DHBT transferred-substrate process. They utilize a double-emitter-finger DHBT unit cell with an emitter area of 2 × 0.8 × 6 μm3each. In contrast to the usual W-band PAs, the proposed single-stage amplifier MMICs do not apply any special reactive matching for the transistor, which leads to very compact chip sizes of 0.27 mm2(S-DPA) and 0.39 mm2(D-DPA). The S-DPA includes one band-pass filter (BPF) at the output with 0.6 dB insertion loss (IL) and 24 dB input return loss (RL) at the signal frequency of 95 GHz. The dual-band BPF shows 0.7 dB IL in both bands with a RL of more than 21 dB each. Applying an overdriven sinusoidal input signal to emulate digital operation the DPAs achieve a maximum output power of 14.4 dBm and power-added efficiency of 31% when using the single-band configuration. Collector efficiencies of more than 80% and the flexible multi-band operation demonstrated prove the great potential of the digital PA concept for future high-speed communications.