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Nikandish, Gholamreza
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Nikandish, Gholamreza
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Nikandish, Gholamreza
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Now showing 1 - 6 of 6
- PublicationBroadband Fully Integrated GaN Power Amplifier With Minimum-Inductance BPF Matching and Two-Transistor AM-PM CompensationIn this paper, we present a design technique for broadband fully integrated GaN power amplifiers (PAs), with merged bandpass filter (BPF) and AM-PM compensation. The minimum-inductance BPF structure is used as the output matching network of the PA. A new theory of the minimum-inductance BPF is developed and it is shown that, compared to the standard BPF, it can be implemented using lower total inductance and provide higher out-of-band attenuation. Furthermore, using a two-transistor architecture, an AM-PM compensation technique is proposed where compressive and expansive nonlinearity profiles of the transistors' transconductance and gate-source capacitance are combined to achieve a linear total transconductance and input capacitance, over a wide power range. A fully integrated PA prototype, implemented in a 0.25- μm GaN-on-SiC process with 28-V supply, provides 35.1-38.9,dBm output power, 45-61% drain efficiency (DE), 40-55% power-added efficiency (PAE), and 11.3-13.4,dB power gain, across 2.0-4.0,GHz. For a 256-QAM signal with 7.2-dB PAPR and 100-MHz bandwidth at 2.4,GHz, it achieves 2.5% (-32.0,dB) rms error vector magnitude (EVMrms) and -37.5/-37.6,dBc adjacent channel leakage ratio (ACLR), while average output power and DE/PAE are respectively 30.1,dBm and 20.6/19.5%, without predistortion. EVMrms and ACLR can be improved to 0.5% (-46,dB) and -46.4/-46.8,dBc by using digital predistortion (DPD).
461Scopus© Citations 17 - PublicationUnbalanced Power Amplifier: An Architecture for Broadband Back-Off Efficiency EnhancementIn this article, we present a new broadband power amplifier (PA) architecture with a back-off efficiency enhancement that supports very wide modulation bandwidths. The unbalanced PA is composed of two cooperating sub-PAs using the Lange couplers as input power splitter and output power combiner. The PA operation is controlled by the transistors' width ratio and coupling coefficients of the Lange couplers. The output power back-off (OPBO) level is given by the transistors' width ratio and coupling coefficient of the output coupler, while the maximum efficiency is achieved at the back-off point. These features provide more design flexibility compared with the conventional Doherty PA, where the OPBO can be set only by the transistors' width ratio, and the maximum efficiency is achieved at the peak power. Using broadband harmonic matching networks, the main and auxiliary sub-PAs operate in the continuous mode to improve efficiency over a broad bandwidth. A fully integrated unbalanced PA, implemented in a 250-nm GaN-on-SiC process, achieves 32.2-34.3-dBm output power, 27%-37% efficiency at peak power, and 27%-40% at 5-6-dB back-off, across 4.5-6.5 GHz. The PA provides 3.7/4.5% (-28.6/-26.9 dB) rms error vector magnitude (EVMrms) and 30% average efficiency for a 256-QAM signal with 100-/200-MHz bandwidth, 7.2-dB PAPR, and 25.5-dBm average output power, without using any predistortion.
Scopus© Citations 15 671 - PublicationBroadband Fully Integrated GaN Power Amplifier With Embedded Minimum Inductor Bandpass Filter and AM-PM CompensationIn this paper, we present a design technique for broadband linearized fully integrated GaN power amplifiers (PAs). The minimum inductor bandpass filter structure is used as the output matching network to achieve low loss and high out-of-band attenuation. Two parallel transistors with unbalanced gate biases are used to mitigate nonlinearity of their transconductance and input capacitance, and consequently, compensate AM-PM distortion of the PA. A fully integrated GaN PA prototype provides 35.1–38.9 dBm output power and 40-55% power-added efficiency (PAE) in 2.0–4.0 GHz. For a 64-QAM signal with 8-dB peak-to-average power ratio (PAPR) and 100-MHz bandwidth at 2.4 GHz, average output power of 32.7 dBm and average PAE of 31% are measured with −30.2 dB error vector magnitude (EVM).
796Scopus© Citations 10 - PublicationThe (R)evolution of Distributed Amplifiers: From Vacuum Tubes to Modern CMOS and GaN ICsBroadband amplification of signals is desirable in many applications such as high-speed data communications, high-resolution imaging systems, optoelectronics, and instrumentation systems. Wide bandwidth is one of the prominent factors to be considered in designing such systems because it determines the system's ability to transfer high-data-rate information, transmit/receive short pulses, and process wide-band signals. Designing broadband amplifiers has always been challenging. The ever-increasing demand for higher data rates and low energy consumption in next-generation communication systems further complicates broadband amplifier design.
1149Scopus© Citations 43 - PublicationA Fully Integrated GaN Dual-Channel Power Amplifier With Crosstalk Suppression for 5G Massive MIMO TransmittersWe present a broadband dual-channel power amplifier (PA) with crosstalk suppression for multi-input multi-output (MIMO) communications. Operation of MIMO system with crosstalk is theoretically evaluated for two popular coding schemes including the space-time coding and linear precoding. Design challenges of a multi-channel PA on a single chip are investigated and circuit techniques, including second-harmonic trapping integrated into the output matching network and the use of back-via lines to isolate the channels, are proposed to mitigate the inter-channel crosstalk. A fully integrated dual-channel PA prototype, implemented using a 250-nm GaN-on-SiC process, provides 34.9–36.3 dBm output power, 44–49% power-added efficiency (PAE), 11.3–12.3 dB power gain, 31.0–34.2 dB second-harmonic rejection, and –28.1 dB to –25.7 dB inter-channel crosstalk across 4.5–6.5 GHz. For a 100-MHz 256-QAM signal with 7.2 dB peak-to-average power ratio (PAPR), the PA achieves 29.9 dBm average output power, 30% average PAE–, 38.2/–39.1 dBc adjacent channel leakage ratio (ACLR), and –28.2 dB (3.9%) rms error vector magnitude (EVM), without using digital predistortion (DPD). Effect of crosstalk on linearity of the dual-channel PA is also measured and it is shown that for a 256-QAM signal EVM can increase by 3–8 dB, depending on relative power levels of the two channels.
325Scopus© Citations 17 - PublicationA Fully Integrated Reconfigurable Multi-Mode Class-F2,3 GaN Power AmplifierIn this paper, we propose a reconfigurable multi-mode fully integrated power amplifier (PA) in GaN technology. The PA is composed of one main transistor, biased in class-AB, and three auxiliary transistors which can be switched between class-AB and deep class-C, to improve efficiency and linearity of the PA. Furthermore, a harmonic termination network is proposed to enable operation of the PA in class-F2,3. A proof-of-concept PA, fabricated using a 250-nm GaN-on-SiC process, provides 33.8 dBm output power and 42% peak drain efficiency (DE) at 4.8 GHz. Modulated-signal measurements using a 200-MHz 256-QAM 7.2-dB peak-to-average power ratio (PAPR) signal indicate that rms error vector magnitude (EVMrms) < 5% (–26 dB) can be achieved with 27.7–28.5 dBm average output power, 26–30% average DE, and –38.1 to –33.5 dBc adjacent channel leakage ratio (ACLR), in the four operation modes. It is shown that ACLR can be improved by 6 dB at lower output power levels through reconfiguring the mode of PA operation.
225Scopus© Citations 2