A third order analogue pre-distorter MMIC for E-band PA linearisation

This paper presents the Direct Current (DC) power budget analysis and Radio Frequency (RF) frontend system design considerations of a medium Power Amplifier (PA) with average power output of 1watt. The PA system analysis is performed in a simulation environment for three linearization usage scenarios such as, Back-off, Digital Pre-Distortion (DPD) and Analog Pre-Distortion (APD) schemes. In the Back-off mode, the total RF frontend power consumption is 35.87 watt and with the usage of DPD topology the power consumption is 32.76 watt while with APD topology, the power consumption is 23.74 watt. The APD topology considers a Commercial off the Shelf (COTS) design topology with using moderately non-linear PA device operation. As compared to the back-off operation, the DPD scheme has got a 8.6% estimated relative power saving and the APD provides an estimated relative power saving of 33.8%.

This brief presents a design method of analog predistorter (APD) for Doherty power amplifiers (DPAs) based on minimum gain and phase deviation to improve the output adjacent channel leakage power (ACLR). To prove this method, the normalized deviation is fomulated based on the non-linear analysis of DPAs’ gain and phase, which is a new joint design indicator between DPAs and APDs. Then an APD design and linearisation performance prediction platform is constructed using this indicator as the core. An APD consisting of two T-networks in series is designed as an example of an existing DPA. It has low circuit complexity and low power consumption, which can effectively improve the AM-AM and AM-PM of the DPA after optimization. Under the excitation of a 40 MHz, 64-QAM modulated signal, the results show that the ACLR of the DPA output is improved by nearly 10 dB with the proposed APD, from -34.4/-34.3 dBc to -43.9/-45.6 dBc. In case of constant output ACLR, the application of the APD also increases the output power and efficiency. Moreover, the proposed APD still has good linearization performance under the excitation of 80 MHz, 64-QAM modulated signal.

In this paper an adjustable-resonance down-conversion Gilbert Micromixer is proposed and investigated. For the circuit realization a 130nm BiCMOS process technology is used. The Micromixer is designed for single-ended to single-ended operation. A differential to single-ended conversion at the output of the mixer is realized by using a tuneable reactive current mirror. The output power can be adjusted by adjusting the center-frequency of the reactive tunable load. In this way, the Micromixer features an almost linear tuning range for output power adjustment. Analog predistortion is used for linearity enhancement. The Micromixer is simulated, designed and measured. A S-parameter and an output power measurement shows the effect of resonance-tuning and output power adjustment. The mixer yields a broadband low-Q matching network and a simulated power conversion gain of −1dB for maximum power adjustment at 28GHz as well as a measured power consumption of 69.3mW.

At Olkaria II power plant located in Kenya, the brine from the separator is re-injected back into the ground. This study analyzes a flash geothermal-solar hybrid cycle using the working fluids n-butane, n-pentane, cyclopentane, hexamethyldisiloxane and toluene in order to utilize the brine. The studied working fluids have no potential to deplete the ozone or cause global warming. The working fluids were analyzed in terms of net power output and pump power required. This was done by heating Therminol VP-1 fluid to a maximum temperature of 400 °C using the parabolic trough solar collector and varying the working fluids mass flow rate, Therminol VP-1 flow rate and pressure, and the brine pressure and flow rate. They were varied to investigate their effect on the power output of the Organic Rankine Cycle. The working fluid with higher net power output was selected as a suitable working fluid for the hybrid cycle. The selected working fluid was used to determine the average hourly power output in each month of the hybrid system using the irradiance of Olkaria II power station. N-butane showed the best results in net power output hence it was selected as a suitable working fluid as compared to the other working fluids. When the hybrid system was analyzed using n-butane to obtain the hourly average power output in each month, the results revealed that the month of February has the highest hourly average power output where the Steam Turbine has an average hourly power output of 10.48 MW and Binary Turbine net power output of 18.56 MW. The minimum average hourly power output was obtained in the month of June where the Steam Turbine has an average hourly power output of 9.08 MW and Binary Turbine net power output of 16.88 MW.

Background: In the field of biomechanical analysis of pedaling motion, researchers studied the relationship between cost energy and cycling technique for optimal use of the force applied to the pedals, to improve cycling velocity for minimal energy cost or to compute the joint powers according to the resistive load. For that, numerous measuring devices have been developed and investigated to evaluate resultant torque and/or power output. Recently, new pedal sensors I-Crankset (ICS) are sold to measure the forces applied to the pedals and to calculate the torque and/or power output produced during cycling. These pedals’ sensors were calibrated and certificated, but it was essential to check if these devices still measured accurately after their integration on an ergometer. Purpose: The aim of this study was to compare dynamically this new device for measuring crankset’s resultant torque, mechanical power and work outputs.  Methods: A subject (Male, 75 kg, 1.82 m, trained rider) took part to this study conducted ethically according to international standards. The rider adjusted the cycle ergometer according to its personal settings. Figure 1 described the test bench. It was composed of: a chainring (A) was used to connect the ergocycle to the bench through a chain and a flywheel (D) associated with a mechanical braking device (E) composed of a tray with additional masses. The evaluation protocol was implemented to achieve three pedaling conditions and so to cover the usual torque and power ranges (Table 1). For each condition, the subject produced a pedaling torque to overcome that resistive load during one trial of 90 seconds. Feedback of cadence was displayed on the Control SRM bicycle computer. The torque reference sensor (model 1641/1648, Lebow) named RTSL (C) was installed on the axis (B). The scientific version SRM sensor was mounted on the crankset of the ergocycle. The ICS sensors were fixed at each pedal. The relative pedal to crank and the crank to ergometer angles were measured using encoders.  Analyzed parameters: As all the signals are acquired at 200 Hz and synchronized, for each cycle and for each acquisition system, we had the same number of acquisitions samples. According to the sample rate and protocol used, more than 12 000 instantaneous measures will be available for the comparison of several devices. Three power outputs were computed through these equations: (1)  with , k is the reduction coefficient between SRM and bench chainrings, ratio of the two diameters. (2) SRM:,  is the average angular velocity of the crankset over the cycle. (3) ICS: ,  is instantaneous angular velocity of the crankset computed from encoders measures. The mechanical work outputs  were given by integration over the time of the power outputs. By design, the SRM only measures an average angular velocity, so we computed mechanical work firstly considering this constant angular velocity () and secondly considering instantaneous angular velocity provided by ICS encoders (). Statistical analysis: For each condition, the same analysis was performed on torque, power and work outputs obtained from the different sensors. These instantaneous parameters, once pedaling cycles normalized, were compared using a coefficient of multiple correlation inter-protocol (CMC ip ) to appreciate the similarity of the instantaneous measures waveforms given by various sensors in a single acquisition of the same parameter. For each condition (n=30 cycles) and for all conditions (n=90 cycles), the averaged torque and power output were computed over each cycle and then these values were compared pairwise of sensors (A Bland-Altman analysis). A global normalized averaged torque evolution over cycles was also computed for condition 1 and for each sensor using.  Results: Mechanical power output comparisons: Table 2 reports all the data for the comparison of the averaged power output measured by the three sensors, for the each condition and all conditions. Especially for condition 3, we note an increase for the power output of the mean bias and error range between SRM and RTSL against those computed for the torque [mean bias: -4.4 ±2.3% for the power vs -1.20 ±0.53% for the torque; error range: 29 W (9.2%) for the power and 0.79 Nm (1.9%) for the torque]. This is not the case for ICS. The figure 3 confirms these results with a 95% limits of agreement larger for the SRM than ICS [respectively -1.81; 7.37 W and -20.70; 9.48 W for ICS and SRM]. Mechanical work output comparisons: Table 3 shows the difference of cumulative output work over thirty cycles between ICS and RTSL then SRM and RTSL for each condition. The differences are also expressed as the percentage of the total cumulated work. To analyze the influence of the angular velocity, we integrated power output over time to compute the work output in using i) the torque and angular velocity measured by SRM (W SRM ) and ii) the SRM torque multiplied by ICS angular velocity (W SRM* ). These results are presented at the last lines of table 4. The relative error is under 2% whatever the conditions, excepted for condition 3 between SRM and RTSL (5.26%). This error can be reduced by using I‰ ICS provided by ICS to compute the W SRM* (1.44 %).  Discussion: Power output discussion. For the power output, we note high values of  between ICS and RTSL (Table 3). For the steady state condition (C1: 210 W), ICS power mean relative error (0.1 ±0.5%) is better than [1] when comparing Velotron cycle ergometer (-0.8% for constant 250 W trial) with a test bench. For condition 2 (150 – 250 W, 80 rpm), ICS results (1.8 ±0.5%, Table 2) are closed to power mean relative error reported by [4] when comparing Powertap (-1.5 ±0.6% for 50-1000 W at 100 rpm trial) with a test bench. As SRM is considered as a gold standard [5], we will try to position ICS against SRM. Before that, we check that SRM results are consistent with literature. The mean relative errors reported by [1] (0.18%) and [4] (0.1 ±1.1%) are lower than errors of the present study (respectively 0.8 ±1.2% for condition 1 and -0.8 ±2.1% for condition 2). These differences can be related to the possibility of the test bench used by [6] to maintain a constant pace along all the cycle unlike the protocol of this study (mean cadence: 8.3 ±0.2 rad/s for conditions 1 and 2). Indeed, it’s difficult for a rider to produce a constant crankset angular velocity like the motorised test bench used by [1] and [3]. [1] shows that a rapidly increasing angular velocity results in a more inaccurate power measurement (mean relative error: -3.3 %; CI = -8.1 to 1.5 %). This is closer to the results for condition 3 (-4.4 %; CI = -9 to 0.2 %). This condition accentuates the inability of the SRM to record, by design, instantaneous crankset angular velocity. For a similar pedaling cadence and power output, the relative mean error (1.2 %) between Powertap ergometer and SRM reported by [2] is comparable with the relative error between ICS and SRM computed for condition 1 (0.9%, Table 3). However, ICS seems to be more accurate than SRM when looking at the individual results obtained for SRM (-2.4%) and ICS (1.2%) against RTSL for all conditions. Consequently, as for the torque, ICS can be considered sufficiently accurate. Work output discussion: Table 3 show the requirement to precisely measure the instantaneous values of crankset angular velocity to calculate the work as part of an energy study of the pedaling motion. Thus, when pedaling with constant angular velocity, the power output computed by SRM () is enough accurate to calculate the work output (). For the conditions 1 and 2, the error respectively equal to 0.98% and 1.16% is acceptable. But when the angular velocity is variable, the error becomes equal to 5.26% for the SRM while it is still under 2% for ICS. This result confirms those obtained by [1] which indicates that a rapidly increasing angular velocity causes an inaccuracy in calculating the SRM power. This error is reduced to 1.44% when the torque measured by SRM () is multiplied by the instantaneous angular velocity measured by ICS (). So, ICS should be preferred for power and work outputs investigations.  Conclusions: The study showed that ICS sensor was an accurate powermeter comparable to a standard reference sensor and to SRM regardless the pedaling cadence (56 to 90 rpm) and the resistive load (18 to 42 Nm). However, ICS was more efficient than SRM for evaluating the work particularly when the pedaling angular velocity various significantly. This study showed that it was therefore essential to measure both instantaneous torque and angular velocity in order to conduct an energy analysis of the pedaling motion.

This paper represents the effects of drain bias on the linearity and efficiency of an analog pre-distortion power amplifier(PA) for wideband code division multiple access(WCDMA) repeater applications. For verification, an analog predistorter(APD) with three-branch nonlinear paths for memory-effect compensation is implemented and a class-AB PA is fabricated using a 30-W Si LOMaS. From the measured results, at an average output power of 33 dBm(lO-dB back-off power), the PA with APD shows the adjacent channel leakage ratio(ACLR, <TEX>${\pm}$</TEX>5 MHz offset) of below -45.1 dBc, with a drain efficiency of 24 % at the drain bias voltage(<TEX>$V_{DD}$</TEX>) of 18 V. This compared an ACLR of -36.7 dEc and drain efficiency of 14.1 % at the <TEX>$V_{DD}$</TEX> of 28 V for a PA without APD.

PURPOSE: The effects of carbohydrate intake on temporal changes in power output during cycling were examined. METHODS: Eight male cyclists (VO2max: 62 ± 6 mL[BULLET OPERATOR]kg-1[BULLET OPERATOR]min-1) completed two trials consisting of 120 min of constant load cycling at 55% Wmax, followed by a simulated 30 km time trial (TT). Subjects consumed 150 ml of a glucose-fructose solution (CHO) or a non-caloric placebo (PL) every 15 minutes during the constant-load portion of the trial, and at 7.5 km intervals during the TT. Average power output during the TT was compared between treatments, and changes in power output within trials were examined across four segments of the TT (S1 = 0-7.5 km, S2 = 7.5-15 km, S3 = 15-22.5 km, and S4 = 22.5-30 km). Power output was also averaged for three minutes immediately before and after each feeding, to determine if changes in pacing between treatments were influenced by the proximity to CHO feedings. Magnitude-based qualitative inferences were used to evaluate differences between treatments and/or time-points. RESULTS: Average TT power output during the CHO trial (242 ± 30 W) was ‘likely’ greater than PL (217 ± 40 W). In the PL trial, cycling power ‘almost certainly’ decreased between S1 (235 ± 41 W) and S2 (223 ± 38 W), and ‘likely’ decreased further during S3 (201 ± 41 W). Subsequently, cycling power ‘very likely’ increased between S3 and S4 (219 ± 43 W), but remained lower than S1 levels. By contrast, power output during the CHO trial showed no clear changes from S1 (246 ± 41 W) to S2 (242 ± 28 W). Thereafter, power output ‘possibly’ decreased during S3 (232 ± 27 W), followed by a ‘likely’ increase in power during S4 (249 ± 32 W), resulting in power levels during S4 that were similar to S1. Power output during the period immediately following each PL ingestion (210 ± 40 W) was not clearly different from the period prior to PL ingestion (213 ± 39 W); whereas power output immediately following CHO ingestion (244 ± 27 W) was ‘possibly’ increased versus pre-ingestion (236 ± 31 W). CONCLUSIONS: CHO ingestion increased average power output during a cycling TT and attenuated declines in power output over the duration of the trial, compared to PL. In addition, improvements in power output with CHO were possibly greater in the periods immediately following each feeding, potentially due to effects of CHO on the central nervous system.

Over the past 20 years the power output produced during many different types of cycling competition have been described (eg., cyclocross, mountain bike, track sprint, men's road and women's road). Little, if any, information is available describing the power output profiles of nationally competitive female road cyclists during the time trial. PUPPOSE: To document the cycling power output produced by nationally competitive female road cyclists during a 20-km time trial (∼30min) and to compare this power output with the maximum mean power output produced during a laboratory based 30-minute time trial (MMP30min) and the power output corresponding to VO2max (MAP). METHODS: On two successive years (Y1 and Y2) members of the Australian National Women's Road Cycling team (Y1 n=8, 25±4y, 168±4 cm, 59±3 kg, 321±20 WMAP, 63±3 ml.kg-1.min-1 VO2pk; Y2 n=6, 23±4y, 166±3 cm, 59±3 kg, 313 W MAP, 62±2, ml.kg-1·min-1 VO2pk) participated in a maximum graded exercise test (125W; inc. 25 W every 3min) and on the subsequent day a maximum 30-min laboratory time trial using a Lode electromagnetically braked cycle ergometer. Within 4 wks cyclists competed in the National Championship time trial event (∼27 km, ∼40 min) using a time trial bike fitted with a dynamically calibrated instrumented crank (SRM, 4 sg model). Power output, velocity and cadence data were sampled at 1 hz. For both years the time-trial was raced on a relatively flat course. A paired t-test was used to compare differences in power output produced in the lab and the field. RESULTS: On both years the monitored cyclist achieved top 10 results at the National Championships. The average laboratory MMP30min was similar for both years (Y1 – 265±22 W, 4.5±.4 W.kg-1; Y2 – 259±15 W, 4.3±.2 W.kg-1), a power output corresponding to 82±4% and 80±3% of the MAP. Compared to the laboratory MMP30min the average time trial power output in the field was ∼10–15W lower (Y1 – 254±15 W, p=.02; Y2 – 250±13 W, p=.01) and demonstrated greater variability. The average power output during the time trial in the field was within 3 W of the power output associated with the onset of blood lactate as calculated using the Dmax technique (Y1 – 256±25 W; Y2 – 253±21 W). CONCLUSIONS: These data are the first to document the power output produced by nationally competitive female road cyclists during a 27-km time trial in the field (>260 W or 4.5 W.kg-1 for ∼40 minutes). In the field power output tends to be lower than in the lab (approximately Dmax power) and more variable possibly due to the slightly longer effort (∼8–1 0min) and forced reductions in power output during sharp cornering in the field.

Endurance performance is a common criterion used to evaluate training or dietary interventions. However, to accurately appraise the effects of an intervention, the endurance performance measure must be reliable. The purpose of the investigation was to establish the reliability of a 1-h endurance performance test. Twenty trained female subjects (peak VO2 = 47.4 +/- 7.2 ml.kg-1.min-1) completed two trials in which they had to generate the highest power output possible throughout 60 min of cycling. Heart rates (HR) and ratings of perceived exertion (RPE) were also recorded during these two trials. All tests were conducted on a wind-braked cycle ergometer set up to closely resemble the subject's own cycle. The trials were separated by 1 wk, conducted on the same day of the week, and completed at a similar time of the day. The average power outputs (+/-SD) for the two trials were 180.0 (+/-18.1) W and 180.0 (+/-20.6) W. The results revealed that average absolute power output, HR, and RPE were not significantly different between trials. The intraclass correlation coefficient (one way ANOVA) for average absolute power output was 0.97, the coefficient of variation was 2.7%, and the SEM was 3.4 W. These results suggest that under controlled conditions average absolute power output during a 1-h endurance test is a reliable measure for trained female cyclists.

This article presents a 28-nm CMOS sub-terahertz (sub-THz) amplitude shift-keying (ASK) transceiver achieving competitive wireless and wireline communication performance. The over-the-air (OTA) link demonstrates 14 Gb/s/0.27 km, 16Gb/s/1m, and 27 Gb/s/12 cm without equalization (EQ), while supporting 64 Gb/s on-Off keying (OOK) and 40 Gb/s pulse amplitude modulation (PAM)4 in wireline mode. In the transmitter (TX), a power-boosting technique is proposed for the oscillator to maximize output power and DC-to-RF efficiency with a compact area. An ASK modulator incorporating analog-pre-distortion (APD) compensation is proposed to support high-efficiency and high-speed modulation. A compact 90–180 GHz power amplifier (PA) is utilized to deliver 15–18 dBm output power, with an integrated broadside balanced balun for differential signal interfacing. In the receiver (RX), a 110–160 GHz low-noise amplifier (LNA) with a switchable differential and single-ended interface is proposed, and a 90–180 GHz wideband envelope detector (ED) with DC-35 GHz baseband amplifier (BBA) is designed for high-speed demodulation. A novel metamaterial-loaded modified Vivaldi antenna and a wideband ground-signal-ground (GSG) pads to waveguide transition (WGT) are proposed for wireless link. The transceiver establishes new benchmarks for silicon-based sub-THz ASK systems, demonstrating the longest reported communication distance with competitive data rates, showcasing extensive communication applications.

Objectives: The purpose of this study was to assess differences in bench press velocity and power production with barbell and dumbbells. Design: Randomized cross-over design. Methods: College men (n = 20, age = 18-24 yrs) were measured for average and peak velocities and power during maximal effort single repetitions using barbell and bilateral dumbbells at loads equivalent to 30%, 50%, and 70% of body mass. Three repetitions were performed at each load with one-minute recovery between each repetition and 10 minutes between loads. During each repetition for each mode, average and peak velocity and power were monitored using a linear accelerometer. Results: Interclass correlation coefficients across the 3 trials for peak and average velocities were high for both barbell (ICC = 0.957 and 0.821, respectively) and dumbbells (ICC = 0.947 and 0.855, respectively). Peak power output was sig nificantly higher (p < 0.009) for barbell than dumbbells at 50% and 70% loads. Average power output was significantly different (p < 0.001) across the 3 loads but not significantly different between barbell and dumbbells (p = 0.35). Although velocity decreased as load increased, higher power outputs were produced across increases in loads. Peak power output was reached at 70% of body mass with barbell and 50% with dumbbells. Conclusion: Either barbell or bilateral dumbbell bench press exercises can be used to evaluate upper-body power with sim ilar effectiveness.

Ultrashort pulses are capable of processing practically any material with negligible heat affected zone. Typical pulse durations for industrial applications are situated in the low picosecond-regime. Pulse durations of 5 ps or below are a well established compromise between the electron-phonon interaction time of most materials and the need for pulses long enough to suppress detrimental effects such as nonlinear interaction with the ablated plasma plume. However, sub-picosecond pulses can further increase the ablation efficiency for certain materials, depending on the available average power, pulse energy and peak fluence. Based on the well established TruMicro 5000 platform (first release in 2007, third generation in 2011) an Yb:YAG disk amplifier in combination with a broadband seed laser was used to scale the output power for industrial femtosecond-light sources: We report on a subpicosecond amplifier that delivers a maximum of 160 W of average output power at pulse durations of 750 fs. Optimizing the system for maximum peak power allowed for pulse energies of 850 μJ at pulse durations of 650 fs. Based on this study and the approved design of the TruMicro 5000 product-series, industrygrade, high average power femtosecond-light sources are now available for 24/7 operation. Since their release in May 2013 we were able to increase the average output power of the TruMicro 5000 FemtoEdition from 40 W to 80 W while maintaining pulse durations around 800 fs. First studies on metals reveal a drastic increase of processing speed for some micro processing applications.

In this paper a highly linear, analog predistorted 28 GHz stacked power amplifier (PA) for 5G is presented. A 130 nm BiCMOS process is used for the circuit realization. The usage of a diode predistorter for analog predistortion is investigated for the stacked PA design and compared to a circuit without predistortion. It is shown, that the linearity of the stacked PA is significantly improved compared to a conventional biasing topology at almost no additional layout size. The measurement shows an overall large signal gain of 14.6 dB and the simulated power added efficiency (PAE) reaches 26 %. The circuit yields a measured input-referred 1 dB compression point (P 1dB ) of 1.5 dBm. Hence, the amplifier is able to provide 16 dBm output power at P DC =40mW. The simulated circuit performance fits well with the measured results.

In this paper, a switchable, passively tuneable 28 GHz to 39 GHz upconversion link for a 5G repeater is proposed and investigated. The upconversion link features an ultra efficient method for output power level adjustment as well as a size efficient broadside coupler for control signal extraction. A tuning range of 7 dB is realized at almost no additional layout effort and zero power consumption. The design yields a measured large signal power gain of 13.8 dB and an input-referred 1 dB compression point of −7.1 dBm; a linearity improvement of 4 dB is achieved by using analog predistortion. For the broadside coupler an insertion loss of −2.2 dB and a coupling of −14 dB is realized. The broadside coupler consumes an area of $340 \mu\mathrm{m} \times 220\mu\mathrm{m}$ .

In this paper, the authors derive a quasi-steady model of an electro-rheological damper under proportional feedback control. Using this model it is shown how, through the choice of two gain terms, the input/output characteristic of the closed-loop system can be linearised. Also, through the choice of a third gain term, the slope of the force/velocity line can be determined. A numerical study compares the performance of openand closed-loop schemes and indicates clearly the working range over which linear behaviour can be obtained.