Improvement In Power Added Efficiency Research Articles

A 28GHz Power Amplifier with Analog Predistortion Linearizer in 65nm CMOS

This paper proposes that a radio frequency power amplifier is suitable for a 5G millimeter wave. It adopts a three-stage single-ended structure at 28GHz. An analog predistortion linearization method is used to improve the linearity of the power amplifier (PA). As a result, there is a significant improvement in power-added efficiency (PAE) and linearity is achieved. The Ka-band PA is implemented in TSMC 65nm CMOS process. At 1.2V supply voltage, the PA proposed in this paper achieves a saturated output power of 15.9dBm and a PAE of 16%. After linearization, the output power at the 1dB compression point is increased by 2dBm, with efficient gain compensation performance.

A Compact E-Band Power Amplifier With Gain-Boosting and Efficiency Enhancement

A compact E-band power amplifier (PA) with gain-boosting and efficiency enhancement technique is proposed and implemented in a 65-nm CMOS process. The proposed gain-boosting unit consists of cross-coupled transistors to introduce negative impedance and improve the quality factor of matching networks. Thus, the power gain and power-added efficiency (PAE) can be substantially improved at the power back-off (PBO) region. Neutralization capacitors are also adopted to improve power gain, reverse isolation, and stability as well. The proposed PA achieves a measured PAE of 22.37%, a ${P_{\mathrm{sat}}}$ of 14.29 dBm, and an ${OP_{\mathrm{1~dB}}}$ of 12.03 dBm with a maximum power gain of 31 dB when the gain-boosting unit turns on. By adjusting the control voltages of the gain-boosting unit, the measured peak gain increases from 26 to 31 dB, and a maximum of 1.7-dBm output power and 5.2% PAE improvement at the input power corresponding to ${IP_{\mathrm{1~dB}}}$ under the gain-boosting unit turned off are achieved. Furthermore, modulation measurement shows that the proposed E-band PA supports 16-Gb/s 16-QAM and 9.6-Gb/s 64-QAM modulated signals with error vector magnitudes (EVMs) of −17.7 dB/−23.1 dB and average output powers of 8.75 dBm/10.41 dBm, respectively. The core area and dc power consumption of the PA are only 0.025 mm2 and 120 mW.

A Highly Efficient X-Band Inverse Class-F SiGe HBT Cascode Power Amplifier With Harmonic-Tuned Wilkinson Power Combiner

A highly efficient sub-Watt X-band inverse class-F SiGe heterojunction bipolar transistor (HBT) cascode power amplifier (PA) is presented. With a multi-harmonic resonance filter and a low loss lumped-element Wilkinson power combiner as an output matching network, the inverse class-F operation is realized successfully and high output power and power added efficiency (PAE) are obtained simultaneously. A cascode configuration with a low base impedance termination and reduced voltage–current waveform overlap extends ${V} _{\rm{CE}}$ swing of the upper SiGe HBT in the cascode beyond BVCBO, leading to improvement in output power and PAE. As proof of concept, the proposed PA was implemented in a 0.13- ${{\mu }}\text{m}$ SiGe BiCMOS technology platform. Measured results shows 53.4% peak PAE with 26.1 dBm output power at 10 GHz, when operated on a 3.0-V supply. No performance degradation is observed after 24-h continuous mode operation. To the author’s best knowledge, this brief has the highest PAE among any Si-based X-band PAs with comparable output power, which demonstrates that the proposed harmonic-tuned Wilkinson power combiner approach is an appropriate solution for efficient PA design at X-band.

A modified class-F power amplifier with miniaturized harmonic control circuit

In this paper, a modified class-F power-amplifier (PA) for GSM applications is designed, simulated and tested. In this design, novel symmetrical meandered lines compact microstrip resonant cell (SMLCMRC), is proposed as a new harmonics control circuit (HCC), which resulted in size compression, power added efficiency (PAE) enhancement, power gain improvement, and better linearization in the PA. In this work both of the conventional class-F amplifier and proposed amplifier with SMLCMRC is designed at 1.8 GHz. The measurements show that the proposed PA with SMLCMRC has 72.54% maximum PAE, 17.13 dB gain and the 1 dB compression point (P1dB) is about 35.1 dBm. These results show, 16.5% improvement in PAE, 1.33 dB increment in gain and 1.1 dB improvement in linearity operating range of proposed amplifier compared to the conventional PA.

Doherty power amplifier with dynamic load modulation for wireless communications

AbstractIn this article, Doherty power amplifier (DPA) with dynamic load modulation (DLM) is proposed for wireless communications with high peak‐to‐average ratio (PAR) signals. The proposed DPA with DLM operates as a conventional DPA from peak to 6‐dB back‐off powers, and DLM starts to operate at lower power than 6‐dB back‐off. The DPA with DLM was designed using 6‐W GaN high mobility transistors (HEMTs) at 1.85 GHz. The fabricated DPA with DLM shows a power‐added efficiency (PAE) of 44.7% at 10‐dB back‐off power of continuous‐wave input signal, which is 5% higher than that without DLM. Dynamic measurement was also carried out using 3.84 MHz W‐CDMA signal with 7.4 dB PAR. The measurement of the DPA with DLM exhibits an average PAE of 32.1% at output power of 27.1 dBm, and adjacent channel leakage ratio (ACLR) of −45.1 dBc, which corresponds to 6.1% improvement in PAE compared with the DPA without DLM.

Active Integrated Antenna Supporting Linear and Circular Polarizations

A patch antenna and class B power amplifier are integrated for size reduction and high power added efficiency (PAE) through harmonic suppression. Harmonic suppressing slits are etched on the patch such that both linear and circular polarizations are supported. The mechanism of the slits is explained, and both components are characterized and examined for performance validation. Measured results show that the harmonic suppression leads to up to 5% improvement in PAE and that the antenna’s radiation pattern is not disturbed by the added harmonic suppressing slits for all supported polarizations.

OFDM信号伝送時の送信電力付加効率と受信S/Nを改善する分離送信法の特性評価

OFDM信号伝送時の送信電力付加効率と受信S/Nを改善する分離送信法の特性評価

Backgate Modulation Technique for Higher Efficiency Envelope Tracking

A novel backgate modulation technique alleviating limitations associated with supply-regulated polar transmitters is proposed. The backgate of a partially depleted silicon-on-insulator metal-semiconductor field-effect transistor with a breakdown voltage of 15 V is used to modulate the gain and output power of an RF power amplifier (PA). The high-impedance backgate provides high-efficiency and wide-dynamic-range modulation of PA gain. Measured results at 1.8 GHz demonstrate 16% power-added efficiency improvement at 6-dB backed-off output power, compared with the same RF PA without backgate modulation.

A Dual-Input Digitally Driven Doherty Amplifier Architecture for Performance Enhancement of Doherty Transmitters

In this paper, the novel architecture of a dual-input and digitally driven Doherty amplifier is proposed with the aim of improving the performance of gallium-nitride (GaN) Doherty transmitters. In this work, the power efficiency is enhanced by using digital adaptive phase alignment to compensate for performance degradation due to bias and power-dependant phase misalignment between the carrier and peaking branches. For experimental validation, the proposed dual-input digital Doherty power amplifier (PA) was implemented using a 10-W GaN transistor. Measurement results demonstrate that the dual-input Doherty prototype exhibited a power-added efficiency (PAE) higher than 50% over an 8-dB output power back-off (OPBO) range. In comparison with the conventional fully analog Doherty PA, this represents a 10% improvement in PAE over the same OPBO range. Using a one-carrier Worldwide Interoperability for Microwave Access signal with a 7-dB peak-to-average power ratio, the dual-input Doherty PA, with digital adaptive phase alignment applied at the input of its peaking path, achieved a PAE of 57% at an average output power of 37.8 dBm, along with a - 22-dBc adjacent channel power ratio (ACPR). This corresponds to an improvement of 7% in PAE and 1 dB in average output power for the same ACPR level in comparison with a conventional fully analog Doherty PA.

GaN HEMT Based High Power and High Efficiency Doherty Amplifiers with Digital Pre-Distortion Correction for WiBro Applications

This paper presents high power and high efficiency Doherty amplifiers for 2.345 GHz wireless broadband (WiBro) applications that use a Nitronex 125-W (<TEX>$P_{3dB}$</TEX>) GaN high electron mobility transistor (HEMT). Two- and three-way Doherty amplifiers and a saturated Doherty amplifier using Class-F circuitry are implemented. The measured result for a center frequency of 2.345 GHz shows that the two-way Doherty amplifier attains a high <TEX>$P_{3dB}$</TEX> of 51.5 dBm, a gain of 12.5 dB, and a power-added efficiency (PAE) improvement of about 16 % compared to a single class AB amplifier at 6-dB back-off power region from <TEX>$P_{3dB}$</TEX>. For a WiBro OFDMA signal, the Doherty amplifier provides an adjacent channel leakage ratio (ACLR) at 4.77 MHz offset that is -33 dBc at an output power of 42 dBm, which is a 9.5 dB back-off power region from <TEX>$P_{3dB}$</TEX>. By employing a digital pre-distortion (DPD) technique, the ACLR of the Doherty amplifier is improved from -33 dBc to -48 dBc. The measured result for the same frequency shows that the three-way Doherty amplifier, which has a <TEX>$P_{3dB}$</TEX> of 53.16 dBm and a gain of 10.3 dB, and the saturated Doherty amplifier, which has a <TEX>$P_{3dB}$</TEX> of 51.1 dBm and a gain of 10.3 dB, provide a PAE improvement of 11 % at the 9-dB back-off power region and 7.5 % at the 6-dB back-off region, respectively, compared to the two-way Doherty amplifier.

An Efficiency-Improved Outphasing Power Amplifier Using RF Pulse Modulation

This letter presents a method for improving the efficiency of an outphasing amplifier by pulse modulating the input signals. By pulse modulating the two input signals to the outphasing amplifier, the outphasing angle can be kept small and hence attain higher efficiency. Whereas, compared to a pulse modulated polar transmitter, the need for high resolution pulsewidth modulation is reduced. To validate the proposed technique, a prototype transmitter system is constructed using commercially available components. Using a CDMA2000 1X signal at 836.5 MHz, the proposed technique achieved a 26% improvement in power-added efficiency compared to a conventional outphasing amplifier at 25.2 dBm output power level while passing the adjacent and alternate channel power ratios for the CDMA2000 standard.

A Charging Acceleration Technique for Highly Efficient Cascode Class-E CMOS Power Amplifiers

A cascode configuration in class-E CMOS power amplifiers (PAs) provides high reliability with respect to breakdown considerations. However, it causes a power loss due to the slow transition of a common-gate device from the triode region to the cut-off region. To minimize the power loss of cascode class-E CMOS PAs, we propose a charging acceleration technique, CAT. This method incorporates a capacitive element between the drain and the source of a common-gate device in a cascode configuration, accelerating the charging speed responsible for turning off a common-gate device instantly after a common-source device is turned off and thus minimizing power loss from the device. We compared the performance of the proposed cascode class-E PA to that of the conventional cascode class-E PA using a 0.18- CMOS process. With a 3.3-V power supply, the proposed fully-integrated CMOS PA achieves 30.7 dBm of maximum output power and 45.6% of power-added efficiency (PAE) with a dynamic range of 40 dB at 1.6 GHz. According to measurements, the proposed cascode class-E PA shows improvement in PAE over the conventional class-E PA of between 5% and 9% in a 1.5 to 2.0 GHz range.

Efficiency enhancement of the Doherty amplifier for 3.5 GHz WiMAX application using class‐F circuitry

AbstractThis article presents a high‐power and high‐efficiency saturated Doherty amplifier using a GaN high electron mobility transistor for 3.5 GHz Worldwide Interoperability for Microwave Access application.The saturated Doherty amplifier is a Doherty amplifier based on class‐F amplifiers, resulting in higher efficiency than a conventional Doherty amplifier. The distributed‐type harmonic control circuit is located between a power transistor and an output matching circuit. From the measured results for a continuous wave of 3.5 GHz, the saturated Doherty amplifier attains a high P3dB of 45 dBm and a power gain of about 8.8 dB. Also, the proposed Doherty amplifier provides a high power‐added‐efficiency (PAE) of 37.7% and a drain efficiency of 42.7% at 6‐dB back‐off output power region from P3dB, which are 8.7% and 5.7% higher than those of the conventional Doherty amplifier. Compared to the single class‐AB amplifier, we obtain 17.7% and 19.7% improvement of PAE and drain efficiency, respectively. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 570–573, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24977

A highly efficient Doherty feedforward linear power amplifier for W-CDMA base-station applications

This paper presents a RF high-power Doherty amplifier for improving the efficiency of a 30-W feedforward linear amplifier used in wide-band code-division multiple-access (W-CDMA) base-station applications. A high-power Doherty amplifier using a single push-pull LDMOS field-effect transistor is proposed as the main amplifier of a feedforward linear amplifier. The peaking amplifier's compensation line and gate bias effects are analyzed at the 6-dB backoff point. From the experimental results of a forward-link one-carrier W-CDMA, a 2.2% power-added efficiency improvement at an adjacent channel leakage power ratio linearity of -60 dBc is achieved in comparison to a conventional feedforward class-AB amplifier.

PAE improvement and compensation of small‐signal gain drift due to temperature on power amplifiers through active biasing

AbstractPower millimetre‐wave band transmitters are commonly formed by a chain of MESFET or HEMT GaAs MMIC power amplifiers. Under large‐signal conditions the reverse gate output current, which appears at the gate port of those devices due to drain‐gate breakdown mechanisms, causes a drop in the power amplifier's power added efficiency (PAE) figure, thus affecting the entire transmitter reliability. Additionally, it is desirable to obtain a stable performance from the transmitters for different ambient temperatures. In particular, millimetre‐wave wireless systems, such as the local multipoint distribution system (LMDS), require constant small signal gain for a wide range of temperatures. In this paper, an active bias network is used to compensate for both effects. The performance of the active bias network is shown to be superior, in terms of the power amplifier's PAE and the compensation of the power amplifier's small signal gain drifts due to temperature, to a conventional resistive divider when used for biasing the power amplifier. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 389–392, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11069

Broad-band power amplifier using dielectric photonic bandgap structure

Two class AB GaAs field-effect transistor (FET) power amplifiers have been designed and fabricated in the 4.4-4.8 GHz range. In the first case, a dielectric PBG line was incorporated in the design to tune the second harmonic. In the second case, a 50-/spl Omega/ line is used with no harmonic tuning. The PBG structure allows broad-band harmonic tuning and is inexpensive to fabricate. A 5% improvement in power-added efficiency was achieved at the design frequency of 4.5 GHz, in both simulation and measurement.

Comments on "X-band 0.5, 1, and 2 Watt power amplifiers with marked improvement in power-added efficiency

For the original article see ibid., vol.38, no.6, p.707-11 (1990). Power-added efficiency results from MMIC amplifiers which were designed, fabricated, and tested based on efforts reported in the above-named work have caused a reassessment of measurements made for that work. The new MMIC amplifiers exhibited a maximum power-added efficiency of 32% in X-band at 1-W output power. These results are significantly lower than the 53% average power-added efficiency for the 1-W hybrid amplifiers previously reported. In a recent experiment on one of the original hybrid amplifiers, the previous efficiency results could not be replicated or confirmed. It is prudent to assume that the earlier amplifier efficiency measurements were in error. >

X-band 0.5, 1, and 2 watt power amplifiers with marked improvement in power-added efficiency

Very efficient X-band MESFET power amplifiers, showing greater power-added efficiency over a wider bandwidth than any X-band amplifiers of comparable output reported to date, are discussed. The amplifiers were designed with attention given to optimum bias, proper harmonic termination, and efficient power combining. These device and design issues are discussed, and a straightforward design method which achieved the increased levels of efficiency is described. >