Development of Broadband Class E Power Amplifier for WBAN Applications

Transcription

1 Volume 118 No , ISSN: (printed version); ISSN: (on-line version) url: ijpam.eu Development of Broadband Class E Power Amplifier for WBAN Applications R. Shankar 1, M. C. John Wiselin 2, B.S.Sreeja 3 1 Research Scholar, PRIST University,Thanjavur & Associate Professor/ECE, Kongunadu College of Engineering &Technology,Trichy,Tamilnadu,India. 2 Head and Professor/EEE, Vidya Academy of Science and Technology, Thrissur,Kerala,India 3 SSN College of Engineering, Chennai,Tamilnadu,India Abstract In this paper, a Class E Power Amplifier (Class-E PA) suitable for Wireless Body Area Networks (WBAN) is proposed. A commercially available RF3931 GaN (gallium nitride) high electron mobility transistor deviceis used in the proposed design, together with an active harmonic load pull analysis of the class E mode. The proposed PA utilizes a band pass filter matching network and operates in the frequency range of 6.78MHz to 2.2GHz. The designed PA is fabricated in FR4 substrate and the measurement results are provided. The designed PA provides 78.5% of maximum power efficiency with a fractional bandwidth of 40 while achieving the gain of 10.8-to db. The maximum output power achieved is 42.9 dbw. Keywords: Broad band power amplifier, Wireless body area networks, Class E Amplifier, Power efficiency. 1 Introduction Future communication systems are driven by the concept of being connected any-where at any time. This is not limited to even in medical area. Wireless medical communications assisting peoples work and replacing wires in a hospital are the applying wireless communications in medical healthcare. Power amplifier generally used in electronics items especially in loud speaker and more items but now they used for medical application also. Early they have less efficiency and power of Class E they are not used for the high frequency application. Now they used for broadband applications. Especially for medical application (WBAN) is a sensor that can help to sense the network that can operate automatically and connect to the various application [1] because it is an wireless device that can be connected to wireless network of wearable computing device and for medical use they have lesser weight then the wired appliances and then they can be portable and the devices in smaller in size and easy use also. Class E power amplifier having high efficiency than other power 1 amplifier, to increase the power efficiency and bandwidth of medical appliances can reduce the power consumption and the process can monitor the patient more accurately. The WBAN have low power radiation [11] and reduces the harmful effects in human body monitoring human body for long time also because they have low power requirement [5]. Class E having short range for high data rates they have more power and accuracy for longer equipments also. WLAN transmitter having low data rates and then they can used for Bluetooth, cellular phones etc. This paper is organized as follows in two ways: First class E power amplifier design and simulation, Second layout of class E power amplifier for (WBAN) medical applications. The design of class E power amplifier having different steps because every steps determined that efficiency, [7] power and stability measurement and to optimize the power amplifier for increase the efficiency that case used for implementation of the medical applications and the transmitter of class E power amplifier having [12] low power dissipation and the sensor of WBAN used to sense the particular area of human body (affected area) now currently they can used for cancer detection also available by using the WBAN even the smaller area also easily detected because of its accuracy and efficiency. In [8] they use the technologies of MESFET HBT that transistor gives lower efficiency and low breakdown voltage with limitation of output power, [2] they achieved highefficiency wideband application by using GaN-HEMT power amplifier based on the method of source pull/load pull simulation has been used to find optimum source, [3] by using suppressing harmonic powers, and the output network using the transmission line, [4,10] by choosing the proper switching frequency can reduces the unwanted power wastage and improving the efficiency up to 72%. The section can be hardware that can implemented in the 745

2 medical machine make that machine should be in smaller in size and high power efficiency that is achievement of this paper. The frequency range of class E power amplifier is 6.78MHz 2.2GHz for the application of broadband power amplifier. 2 Power amplifier design The design of general power amplifier having some specific steps and then that determines how much efficient and gain of designing here the power amplifier steps are in four ways they are DC load line analysis, Bias and stability, Load pull analysis, Impedance matching and then to optimize because to improve the efficiency value. the current as well as it reduces the power consumption so they give good efficiency. The achievement from the simulation is determined that voltage value should voltage drain source (VDS) is 5.00V and then the device power consumption Watts can be determined so that if increasing the voltage decreasing the current values should be efficient. 3 Bias and Stability The biasing and stability of class E power determines that, the biasing is used to reduce the error of device so that it gives perfect error correction that depends upon the DC Load line because the transistor or the device which should be in correct region or else it will make the device in suitably fixed in device characteristics so that biasing is must. The stability has two different conditions that should be satisfied so that device should be in stability and biasing for more accuracy of the device and make the device should be suitable biasing for satisfying the stability conditions, they have conditions of Figure 1. Circuit diagram Stability factor Stability measure The detailed discussion of Figure 1 mentioned that information of RF as an input and same RF should be output that is they used for high frequency measurement and C4 is used for distortion 2.2pF, for biasing and stability to reduce the resistor (for flow of current) C1,C2,C3 respective values are 0.1uF,100pF,22pF is used. The impedance matching is used for input and output matching to reduce the signal reflection and the capacitor of C7, C8 used for achieving the high gain and high efficiency and device should be centred in circuit. 2 DC load line Analysis Generally the DC load line analysis is used to determine characteristics of the device here the device is RF3931 device for class E power amplifier, they have load line between the voltage and current values and they have three characteristics region they are[1] Active region [2] Saturation region [3] Cut-off region. The active region shows that they have maximum current values that only determine the load line and Q point in the characteristics. The Saturation region determines that have maximum current and minimum of voltage and this is also called it has saturation current region. The cut-off region determines that they have maximum voltage and minimum current and this is vice versa to saturation region. The centre point is called quiescent point region. The observation of DC Load line is, if increases the voltage it will decreases 2 A. Stability factor The stability factor determines that they having k constant that is also called it has k factor that should be greater than or equal to one. B.Stability measure It is used for quantifying its accuracy and precision and stability measurement it should be lesser than the one. By satisfying this two conditions will determines the power amplifier having good bias and stability condition in it. 4 Loadpull analysis The load pull analysis is determined that the set of contour that shows their results in smith chart and it gives maximum output power by its load impedance and it is very important to determine the actual impedance of the device it should increase the gain and source impedance by using this load pull will determined the impedance matching the device gives the gain as at maximum power and then the values of impedance should determine by the load pull analysis power added efficiency up to 72% and the output power should be in dbm. It is mainly used to improve the gain value first that achieves up 746

3 to db, and then source power will be calculated up to 32 dbw, load pull shows in smith chart analysis. 5 Impedance matching In amplifier, impedance matching is a practice of designing the input impedance of an electric load or the output impedance of the signal source. The impedance matching is either used to maximize the power transfer or minimize the signal reflection from the load. The impedance matching is very important to determine the characteristics of power added efficiency (PAE) 32 for 1GHz and then optimization is done to improve the efficiency by using the tuning process it will increases up to 64 percentages of efficiency and the impedance matching will be shown in it. The input impedance and output impedance are calculated by the load pull analysis output that same value should be used in it and to improve the matching network using the one tone amplifier and the two tone is used for slider power input and spectrum analyzer can be measured for 1GHz value. The slider can used to calculate the Adjacent Channel Power Ratio (ACPR) that power ratio of class E power amplifier is 28 power input (Pin) and the spectrum reaches up to 64 dbm for 1GHz values. Figure 3. Layout of Lumped Components The layout of complete design in Figure (3) with its measurements the breadth of the layout is and and the length of the measurements is and they dimension needs the specifications in order to specify the area required for the layout determinations. This will show the accurate Class E power amplifier having high efficiency for the medical applications. Figure 2. Layout for transistor via ground The layout generation determines the efficiency of the devices this paper achieves high efficiency up to 64 dbm for the application of broadband power amplifier and they have ground generation layout, the transistors placed via the ground and that placement determines the power of the amplifier and determines the various connectionless transistor is developed in it. The process of lumped components that shows a different areas component can be placed in Figure (1) is shown. The fabrication process can have hardware simulation and then the different components can be attached in single board to minimize the area of broadband applications. Figure 4. Layout of complete design of class E power amplifier The layout mentioned that the size of the device should be reduced by choosing the proper switching frequency reduces the power dissipation by reducing the current values it reduces power consumption in the device and usage of device is higher and the process of device for long time applications. And the hardware simulation determines the complete class E power amplifier efficiently achieved. The layout generation denotes the size of the power amplifier is reduced and comparably increasing the efficiency

4 maximum of output power is higher that shown in Table 1 is 42.9 (dbw) is measured in power amplifier. Table 1. Comparison for different values of Gain and Power added Efficiency Figure 5. Fabrication of Power Amplifier 6 Measurement results The results shows that output power Vs gain, the gain increases for particular frequency and then decreases suddenly in the range of 41dBm values, and then power ration should be calculated in the power added efficiency is difference the RF output power and RF input power by RF DC power gives the power added efficiency values from the class E power amplifier for WBAN application the efficiency value is higher from this they reach up to 45dBm values this is the major advantage is improvement in the efficiency and the gain value is up to 15dB. Index Frequency bands (GHz) Fracti onal band width (%) PAE (db) at Pmax (%) PAE at 6 db OBO (%) Gain (db) [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] This Work Max. no Pout (dbw) Figure 6. PAE (%) versus output power (dbm) 7 Conclusion This paper gives a broad review of GaN HEMTs in terms of high efficiency for broadband applications. The design of class E power amplifier for efficient high power amplifier for the frequency range of 6.28MHz-to 2.2GHz, produces the high efficiency obtained for low power level and maximum power added efficiency of 50.8-to 78.5%. The proposed class E power amplifier design within this frequency is used for medical applications and wireless networks (WBAN) they have short range of high data rate communication that reduces the harmful effects for human body and monitor them accurately. This method is very well suited for wireless medical application. Figure 7.. Gain (db) versus output power (dbm) The process of WBAN having the frequency range of 6.78MHz to-2.2ghz and the graph shows that output power values and then range of gain values and power added efficiency for showing the effectiveness of the medical applications. The range of class E power amplifier is fractional bandwidth of WBAN is 40, and the power added efficiency at maximum power should be 78.5% and the gain is 10.8-to 14.8 db values and 4 References 1. M. Acar, A. J. Annema, and B. Nauta, Analytical design equations for class-e power amplifiers, IEEE Trans. Circuits Syst. I, Reg. Papers,vol. 54, no. 12, pp , December R. Brama, L. Larcher, A. Mazzanti, and F. Svelto, A 30.5 dbm 48%PAE CMOS class-e PA with integrated balun for RF applications, IEEE J. Solid-State Circuits, vol. 43, no. 8, pp , August M. J. Deen, M. M. El-Desouki, H. M. Jafari, and S. Asgaran, Lowpower integrated CMOS RF transceiver circuits for short-range 748

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