Design of an Analog Active Phase Shifter by Using HEMT Technology in Frequency Range of 4-6GHz

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1 TERNATIONAL JOURNAL OF COMPUT CIENCE, VOL. 1, NO. 1, JANUARY 2012 IN (Online): , IN (Print): , Published online January, 2012 ( 12 esign of an Analog Active Phase hifter by Using HEMT Technology in Frequency Range of 4-6Hz Elias Abbasi and M. Reza Kouchaki Abstract In this paper it is proposed to design a new active phase shifter based on all pass networks with the ability of degree shifting of phases operating at 4-6 Hz frequency range. The architecture of this phase shifter is designed by using of High Electron Mobility Transistors (HEMT) based on aas technology for its amplifier design. In this paper both of Active and passive impedance matching and the effect of Noise, stability and scattering parameters on each of them are comprised. Also the tolerance of variety parameters such as bandwidth, impedances, inductors and capacitors is examined. P I. TROUCTION HAE shifters are used widely in phased array antennas for electronic beam directing. Variable types of them are an important part of many radars and communication systems such as in many military applications where a fast beam scanning is required. Phase shifters in most of traditional methods have been developed with passive components. ome of those methods could put out correct time delay, but most of them were impractical for integration with multiple arrays in a commercial process because of their physical dimensions. Also most of them need typically, more than two stages to compensate for their large loss which these types of phase shifter always suffering from it. In comparison with passive phase shifters, active phase shifters could provide continues phase shifts with lower loss [1]-[3]. In recent design of active phase shifters, controlled Varactor method achieve an especial place in analog type due to use of input control which increases the accuracy of phase shifts. The Control element of these phase shifters are voltage variable capacitors or varactor diodes. In this paper a new active analog phase shifter was designed by using of HEMT transistors for its Varactor capacitor in MMIC technology. This is faster than MEFET transistors. It was also shown that the presented design is more efficient and works properly with lower noise [4]-[6]. speed is more purifying to lessen the Transistor resistance, but it also has some limits, too. Therefore in order to have higher speeds, there should be found some ways to increase the carriers in none-purified semi conductors to get to maximum mobility. This situation can be used in the structure of segments which are designed as HEMT. HEMT operation is quite different from kinds of FET and has better efficiency in Microwave radio usages than standard conjunctions or MOFET.In this structure 5000 cm2/vs of electrons movement can be created in 77C of temperature and also with some special tips we can reach to the mobility coefficient of cm2/vs. These parameters in comparison with its amount in aas (4000cm2/vs) and in i (800 cm2/vs) is too high. Another parameter which affects the speed of HMET transistors is the different structure of semi conductors and eliminating the interference in various apparatus. In fact it was impossible to reach the much higher speed until the improvement of recent parameters. Also, with the change of bias voltage in the range of 0.5 V to -2V in HEMT, the most capacitor change which is around 7 could be reached, while with this voltage variation in MOFET the most capacitor change could be reached just around 3. An important clue in this paper is that it can be used as a Varactor in MMIC circuits. The Range of capacitors changes and chart of capacitors chart can be optimized with specifying appropriate coefficient in Al X a 1-x As. III. PHAE HIFTER EIN Figure 1 shows a rain to ource connected HEMT transistor which is used in this paper. The rain voltage has a controlling role which by changing it the capacitor of the circuit will be changed. Also the resistance of this circuit in comparison with its capacitor could be negligible due to its stability against changing of controlling voltage. hifted Phase is calculated by these equations: II. HEMT TECHNOLOY The advantages of aas Transistors versus ilicon types are the high mobility of electrons in these kinds of emi-conductors. This high mobility gives the ability to have less resistance and more speed. A good, known solution to approach the higher Manuscript received ecember 30, 2011; accepted January 12; Elias Abbasi is with epartment of Electrical Engineering cience and Ressearch Branch, Islamic Azad University, Tehran, Iran ( abbasielyas@ gmail.com). M. Reza Kouchaki is with epartment of Electronic, harif University of Technology, Tehran, Iran.. HEMT Transistors are used for amplification and main part of phase shifter in this design. As it is shown, Varactor is used to control the circuit. In this paper a new designed circuit by using HEMT Transistor is used instead of Varactor diode because of specifications, which has been described in previous section.

2 TERNATIONAL JOURNAL OF COMPUT CIENCE, VOL. 1, NO. 1, JANUARY 2012 IN (Online): , IN (Print): , Published online January, 2012 ( 13 RP7 R=R2 Ohm 1 Num=1 fe2onl1 FP3 wu=w um nbd=n RP5 R=R1 Ohm RC5 Vdc=vt V Figure 1. rain to ource Connected HEMT Transistor IV. EIN PARAMETER FORE APPLY MATCH NETWORK By biasing the transistors of the circuit, other elements could be selected basis on the stability, great matching of input/output and phase changes. Analyzing of parameters and Noise figure will be discussed later. Figure 2 shows the whole A designed circuit and the parameters for maximum and minimum phase shifts due to changing the controlling voltage. Figure for the range of 4-6 Hz frequency with V=2.2V and -2.2V. 11 parameter for the range of 4-6 Hz frequency for V=2.2V and -2.2V is given in Figure 4. V. APPLY OF IMPEANCE MATCH NETWORK As two inductors at the input of designed circuit have the role of passive impedance matching network, so there is not any need to have an extra impedance matching network. After applying impedance matching network at the output, the amount of circuit parameters will be verified, also this affects the matching of input; this will force more other changes to the circuit. o there is no need to apply any matching network at the input. Figure shows designed phase shifter after applying passive matching impedance. In comparison with no matching after applying output matching network, the amounts of controlling voltages are verified to achieve the maximum and minimum phase shift. It is completely founded that the matching parameters are improved in both of input and output; also an appropriate noise is obtained. 11 for the range of 4-6 Hz frequency with V=2.2V and -2.2V is presented in Figure 3. Figure parameter for the range of 4-6 Hz frequency for V=2.2V and -2.2V

3 B E TERNATIONAL JOURNAL OF COMPUT CIENCE, VOL. 1, NO. 1, JANUARY 2012 IN (Online): , IN (Print): , Published online January, 2012 ( 14 RC1 Vdc=vd1 V RP1 R=rd1 Ohm RC3 Vdc=vg2 V RlE 2AH RP8 R=rg2 Ohm RP4 R=rd2 Ohm RC4 Vdc=vd2 V 1 Num=1 inde2ah IP2 L=L1 nh cbetee 2 inde 2AH CP5 IP3 C=C1 pf L=L2 nh RlE2A H RP2 R=rg1 Ohm fe2onl1 FP1 wu=w1 um nbd=n1 RP3 R=r6 Ohm inde2ah IP1 L=l3 nh cbetee 2 CP6 C=C2 pf fe2onl1 FP2 wu=w2 um nbd=n2 CP8 C=C4 pf inde 2AH IP5 L=l5 nh inde2ah CP 9 IP4 C=c5 pf L=l4 nh 2 Num=2 V _C RC2 V dc=vg1 V fe 2ONl1 FP3 wu=w3 um nbd=n RlE 2AH RP5 R=R3 Ohm CP7 C=C3 pf RP6 R=R4 Ohm RC5 Vdc=vt V CP11 C=C5 pf 1 Num=1 RC8 Vdc=V1 V RP10 R=R1 Ohm CP12 C=C6 pf fe2onl1 FP5 wu=w4 um nbd=n4 RC9 Vdc=V2 V inde2ah IP5 L=L1 nh inde2ah IP6 L=L2 nh CP5 C=C1 pf RP2 R=rg1 Ohm RC2 Vdc=vg1 V RC1 Vdc=vd1 V fe2onl1 FP1 wu=w1 um nbd=n1 RP1 R=rd1 Ohm RP3 R=r6 Ohm inde2ah IP1 L=l3 nh CP6 C=C2 pf fe2onl1 FP3 wu=w3 um nbd=n RC3 Vdc=vg2 V RP5 R=R3 Ohm RC5 Vdc=vt V RP8 R=rg2 Ohm CP7 C=C3 pf fe2onl1 FP2 wu=w2 um nbd=n2 RP4 R=rd2 Ohm RP6 R=R4 Ohm RC4 Vdc=V3 V CP8 C=C4 pf wu=w5 um nbd=n5 RP9 R=R2 Ohm RC6 Vdc=V3 V fe2onl1 FP4 RC7 Vdc=V4 V inde2ah IP4 L=L4 nh CP9 C=C7 pf CP10 C=C8 pf 2 Num=2 Figure 2. A esign Circuit

4 TERNATIONAL JOURNAL OF COMPUT CIENCE, VOL. 1, NO. 1, JANUARY 2012 IN (Online): , IN (Print): , Published online January, 2012 ( parameter for the range of 4-6 Hz frequency for V=2.2V and -2.2V is shown in Figure 5. Figure 7. Noise parameter for the range of 4-6 Hz frequency for V=2.2V and -2.2V Figure parameter for the range of 4-6 Hz frequency for V=2.2V and -2.2V. Phase shift for 4-6 Hz frequency for V=2.2V and -2.2V is shown in Figure 6. VI. APPLY ACTIVE IMPEANCE MATCH NETWORK Applying active impedance matching networks of final phase shifter is configured by applying the active matching network in the input and output and eliminating two inductors in the input which have the role of matching impedance [Fig. ]. The improvement of the input and output matching is compared with passive matching impedance in different parameters. 11 parameter for 4-6 Hz frequency for V=3V and -3V is shown fin Figure 8. Figure 6. Phase shift for 4-6Hz for V=2.2V and -2.2V Noise parameter for the range of 4-6 Hz frequency for V=2.2V and -2.2V is shown in Figure 7. Figure parameter for 4-6Hz frequency for V=3V and -3V

5 TERNATIONAL JOURNAL OF COMPUT CIENCE, VOL. 1, NO. 1, JANUARY 2012 IN (Online): , IN (Print): , Published online January, 2012 ( parameter for 4-6 Hz frequency for V=3V and -3V Figure 11. Phase shift for 4-6 Hz frequency for V=3V and -3 V Figure parameter for 4-6 Hz frequency for V=3V and -3V Noise parameter for 4-6 Hz frequency for V=3V and -3V is shown in Figure parameter for 4-6 Hz frequency for V=3V and -3V is shown in Figure 10. Figure 12. Noise parameter for 4-6 Hz frequency for V=3V and -3V Figure parameter for 4-6 Hz frequency for V=3V and -3V Phase shift for 4-6 Hz frequency for V=3V and -3 V is shown in Figure 11. VII. EFFECT OF TOLERANCE By considering about 5 as the worth amount of tolerance in circuit elements construction, the effect of toleration in thickness of transistor s ate, Bias impedance of transistors, inductance and capacitors of the designed circuits on the output will be analyzed in this section.

6 TERNATIONAL JOURNAL OF COMPUT CIENCE, VOL. 1, NO. 1, JANUARY 2012 IN (Online): , IN (Print): , Published online January, 2012 ( 17 Table 1- Effect of 5 tolerance on transistor gate width Increment 5 ecrement 5 db((2,1)) phase((2,1)) db((2,2)) db((1,1)) Nfmin tab Fact Table 2- Effect of 5 tolerance on transistor bias resistors Increment 5 ecrement 5 db((2,1)) phase((2,1)) db((2,2)) db((1,1)) Nfmin tab Fact Table 3- Effect of 5 tolerance on Inductance and capacitance Increment 5 ecrement 5 db((2,1)) phase((2,1)) db((2,2)) db((1,1)) Nfmin tab Fact Table 4- Effect of 5 tolerance on whole of circuit elements Increment 5 ecrement 5 Type Analog by varactor Active digital with MMIC ferroelectric CPW Active analog whole pass Passive Active digital with MMIC Analog with MMIC Table 5- comparison between previous designed By Han-c hed.war ner B.caill on Jose Alons o Nam- Hwan g V.F.F usco In this projec t Frequency Band ain (db) Phase changing (egree) Year Hz ((-4)-10) Hz (0-0.8 ) Hz 6 db Hz Hz Hz (-1) Hz 4-6 db REFERENCE [1] C. F. Campbell and. A. Brown, A compact 5-bit phase-shifter MMIC for K-band satellite communication systems, IEEE Trans. Microw. Theory Tech., vol. 48, no. 12, pp , ec [2] C. Moye,. akamoto, and M. Brand, A compact broadband, six-bit MMIC phasor with integrated digital drivers, in IEEE Microwave Millimeter-Wave Monolithic Circuits ymp., 1990, pp [3] H. Hayashi, T. Nakagawa, and M. Muraguchi, A miniaturized MMIC analog phase shifter using two quarter-wave-length transmission lines, IEEE Trans. Microw. Theory Tech., vol. 50, no. 1, pp , Jan [4] F.-J. Huang and K. O, A 0.5 _m CMO T/R switch for 900 MHz wireless applications, IEEE J. olid-tate Circuits, vol. 36, no. 3, pp , Mar [5] H. Lee,. Kang, C.-H. Kim, and. Hong, AKu-band MOFET phase shifter MMIC, in IEEE MTT- Int. Microwave ymp. ig., vol. 1, Jun. 2004, pp [6] H. Zarei and. J. Allsot, A low-loss phase shifter in 180 nm CMOfor multiple-antenna receivers, in IEEE Int. olid-tate Circuits Conf.Tech. ig., Feb. 2004, pp db((2,1)) phase((2,1)) db((2,2)) db((1,1)) Nfmin tab Fact VIII. CONCLUION Table 5 shows the comparison between previous designed phase shifters with this new method is shown. According to the above results it is obvious that, the changes of outputs of the circuit and its sensibility to the noise and stability of tolerance of circuit elements could be negligible.