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18-45GHz DBM

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18-45GHz DBM

  1. 1. A 18-45 GHz Double-BalancedMixer with Integrated LO Amplifier and Unique Suspended Broadside-Coupled Balun Henrik Morkner, Sushi1 Kumar, Michael Vice Agilent Technologies Wireless Semiconductor Division, R&D 350 West Trimble Road, San Jose, Califomia, 95131, USA Abstract - An ultra wide band double-balanced mixer with integrated LO buffer amplifier has been developed using 0.1511 depletion mode PHEMT technology. The mixer employs a unique broadside- coupled balun for superior 18-45 GHz bandwidth and overcomes many of the disadvantages of edge coupled transmission lines in microstrip or stripline. The mixer utilizes GaAs HEMT S-D diode mixing and integrates LO power amplifier to ease the drive requirements typically associated with this type of mixing. The LO amplifier has a. distributed input stage and sequential traditional common source FETs for eficient power amplification. The LO can also be sub-harmonically pumped for 2x frequency multiplication as well as fundamentally driven. The result is a mixer capable of -10 dB conversion gain for up or down mixing across many commercial frequency bands for 18-45 GHz. LO power requires only 0 dBm. I. Introduction Commercial radios operating in the 20-43 GHz bands (1 8, 23, 26, 24.1, 32, 33, 38, and 42 GHz) for Point-to-Point, LMDS, and satellite communication applications utilize mixers for. primary frequency conversion. While narrow band mixers can be built, the usage of a broadband mixer simplifies inventory. System design can be further simplified by integrating a broadband LO amplifier that can be used for either primary or sub-harmonic LO drive. This paper describes a single MMIC that provides such a solution. It was developed to provide a low cost product for many systems and frequencies. Figure 1 shows the complete implementation of the monolithic double-balanced mixer with integrated LO amplifier. Double-balanced mixing is obtained using a traditional diode ring quad. LO amplification is done with a 4 stage single ended amplifier for optimum current efficiency. To combine the single ended RF and LO signals, a unique planar balun is employed. All these elements work together to create a system friendly and volume manufacture product. This MMlC is available from Agilent as part number AMMC-3040 [I] and as a mixeribalun alone version as the AMMC-3041 [2]. Figure 1. 18-45 GHz mixer with LO amplifier. Die size is 2.52 mm X 0.76 mm (Agilent AMMC-3040) 11. Balun Design A traditional balun over a 20-40 GHz band would utilize edge coupled balanced transmission lines in microstrip or stripline to convert a single ended RF signal source into a ground centered balanced LO source. There are several uniplanar mixers that contain CPW and slotline transitions, which serve as a I80 hybrid [3,4]. These are often limited in operating bandwidth and size due to their quarter- wavelength CPW lines. These result in physically large and consequentially lossy baluns. Even when implemented by adapting a lumped-element CPW-to-slotline transition [5] to reduce size, the bandwidth is still lacking. Our unique design does not depend on the edge-coupled techniques but instead suspends a metal 2 layer over a contacted metal 1 layer to make a broadside-coupled balun. A photograph of the suspended system is shown in Figure 2 (Patent pending). Figure 2. Planar balun metal-over-metal system 0-7803-7833-4/03/$17.0002003 IEEE 267 2003 IEEE GaAs Digest Authorized licensed use limited to: Access Provided by Avago Technologies. Downloaded on July 14,2010 at 23:37:18 UTC from IEEE Xplore. Restrictions apply.
  2. 2. 111. Fabrication A two metal layer planar balun as described lends itself to a semiconductor integrated process. While any process that utilizes airbridge could be used, a 0 . 1 5 ~ gate pseudomorphic high electron mobility transistor (PHEMT) is selected. This is due primarily to the ability to integrate the LO amplifier rather than diode or balun capabilities. The foundry used is a modem facility capable of high volume, high yield, and 6-inch wafer production. With typical gate sizes of 0 . 1 5 ~and FTof 70 GHz this process is well capable for this application. Typical process guaranteed specifications are shown in Table 1 . Table 1. Typical PHEMT performance Gain dB 19 11(k Figure 3. Mixer schematic Figures 4a & 4b. 18-45 GHz Mixer MMIC. Die size 0.96mm~0.76" (Agilent AMMC-3041) - I I I I I I I I I I ~O I ! ! > , , , / , / , , ~ 18 20 22 24 26 28 30 32 34 36 30 40 42 44 RF Freq. [GHz] 6 7 0 9 10 11 12 13 14 15 16 17 18 LO Input Power Idem] Figures Sa & 5b. 18-45 GHz Mixer performances 268 Authorized licensed use limited to: Access Provided by Avago Technologies. Downloaded on July 14,2010 at 23:37:18 UTC from IEEE Xplore. Restrictions apply.
  3. 3. lV.LO Amplifier Design The LO amplifier is a 4 stage design. The first stage is semi-distributed to maintain a broadband match while the 2"' through 4" stages are basic common source amplifiers. Interstage matching and DC bias structures are carefully designed to maintain gain and power over the 20-40 GHz band. The LO amplifier is very similar to a stand-alone product from Agilent as the AMMC-5040 [6]except the bias is optimized for mixer drive at 3.5V and 250mA. The schematic for the amplifier is shown in Figure 6. One unique attribute of this topology is that the combination of a broad bandwidth 1" stage and harmonic amplification of the subsequent stages allows sub-harmonic mixing as well as functional up or down conversion pumping. Table 2 and Figure 7 detail the performance. Parameter Unit 1 Min Band Width GHz I Gain dB I 2 0 V. Application and Usage The Mixer with LO amplifier is designed to be used in a hybrid system with user placed bond wires and substrates. Die attach can be eutectic or epoxy, but precautions were made for proper thermal conduction. Since the MMIC incorporates all tuned elements and presents 50 Ohms to the outside port, it lends itself very well to automated assemble and usage. Figure 8 shows a Single drain and single gate supply assembly for standard LO amplifier and Up/Down Mixer applications. Figure 9 shows a separate first-stage gate bias supply for use of a LO as an amplifier or multiplier application for simple mixing or sub-harmonicpumped mixing. These are typical configurations for test and usage All graphed results reported were measured using these configurations. Typ I Max 21-43 I 25 I 26 Figure 6.LO amplifier Schematic Output Retum Loss -Isolation Isolation -8 -14 dB 55 dB 55 Gain Flatness 1 dB I I +/- 1.5 I OuIputPowerP-l dBm I 19.5 1 21 I 23 Outpt Power Psat 1 dBm I 21 I 22 I 2 4 I Innut Retum Loss 1 dB I -15 1 -17 I I 25 45 n 15 ~, 20 25 30 35 40 Frequency [GHz] Figure 7. Typical LO Amplifier Gain & Power To Vw DC Drain 2100 DF Cb TU~ SupplyTo VccFeedDC Gate Figure 8. Configuration for standard LO amplifier and UplDown Mixer applications. To Voo DC Drain Figure 9. Configuration of LO for multiplier application for simple Mixer or sub-harmonicpumped Mixer. 269 Authorized licensed use limited to: Access Provided by Avago Technologies. Downloaded on July 14,2010 at 23:37:18 UTC from IEEE Xplore. Restrictions apply.
  4. 4. V. Complete Mixer w/LO Results The complete 18-45 GHz mixer with integrated LO amplifier was fabricated and tested as shown in figure I . Die size is relatively small at 2.5mm x. 76". and tested 100% on wafer. Typical results based on 6 lots and over 20,000 units measured is shown below in Figure IO. Typical up conversion loss, down conversion loss, LO drive power is shown. Table 3. Mixer w L 0 performance (AMMC-3040) IF : Conversion Loss LO Drive Level Parameter I Unit I Min I Typ 1 Max Band Width I GHz I I I DC DC-3 5 dB IO 12 DBm RF : 20 20-43 43 LO : I I20 120-43 43 I With LO amp Isolation LO=RF Output Power P-1 -6 0 +4 dB 30 dBm Down-conversion LO Return Loss Without LO am -10 12 F = 11 8 10 In 2 0 E 9 C 8 m : 6 ._ z 7 - 6 - 5 - 4 - 3 - 2 - 1 0 1 2 3 4 5 6 LO Input Power [dBm] Figure 10. Up Conversion Loss vs. LO Power 14.0 12.0 go.0 i8.0 6.0 4.0 2.0 0.0 . . . . . . 18 20 22 24 26 28R~fm23GH~f 36 38 40 42 44 Figure 11. Conversion Loss vs. Frequency VI. Conclusion An IS-45 GHz double balance mixer with integrated LO amplifier has been built and demonstrated. The mixer has a broader bandwidth and lower LO drive requirements that any other know product on the market. The design utilizes a unique balun system (2 patents pending) to achieve smooth performance in a small size. Final results show an about IO dB conversion loss over the entire bandwidth with only a 0 dBm LO drive requirement. The final product bas high yield and viable for commercial applications and will be release for general sale by Agilent in late 2003. Acknowledgments The authors wish to thank Jim Gong, Kai Chia, Hue Tran, Kohei Fujii, Bob Myers, Monique Bruner, Gary Carr, Irene Armenta, Frank Ha, Ro Buted for their bard work and WIN Semiconductor of Taiwan for their professional MMIC foundry service. REFERENCES AMMC-3040 Agilent Technologies Data Sheet, // AMMC-3041 Agilent Technologies Data Sheet, // H. Gu and K. Wu, "A Novel Uniplanar Balanced Subharmonicallypumped mixer for Low-cost Broadband Millimeter-wave Transceiver Design", /E€ MTT-S /nt. MicrowaveSymp. Dig.,June 200, pp 635-638. K. Hettak, E. Rius, J. Ph Coupez, S.Toutain. P. Legaud. E. Penard. "A Novel Uniplanar Bi- Phase (0-180) Modulator/Mixer", /E€€ MicrowaveSystems Conference, May, 1995 H. Wang, Y. Lin. H. Wang, C. Chen. "A Q- Band Uniplanar MMIC Diode Mixer with Lumped-Element Coplanar Waveguide-to- slotline Transition", /€E€ MTT-S Int. MicrowaveSymp. Dig.,June 203, pp 103-106. AMMC-5040 Agilent Technologies Data Sheet, // Tutt, M.N. et al., "A low loss, 5.5-20GHz Monolithic Balun", /E€€ MTT-S 1997,pp.933. Mongia et al., "RF and Coupled Line Circuits", Artech House, 1993 Tsai. C. M.. and K.C. Gupta, "CAD Procedures for Planar Re-Entrant Type Couplers and Three-Line Baluns." /€E€ MTT- S 1993, pp.1013-1016. [IO] Maas, Stephen A. "Microwave Mixers", Znd ed., Norwood. MA: Artech House, 1993 [II ] K.Fujii, H.Morkner, "E-PHEMT, Single Supply, Power Amplifiers for Ku Band Applications",/E€€ 2003 MTT-S Symposium, June 2003. 270 Authorized licensed use limited to: Access Provided by Avago Technologies. Downloaded on July 14,2010 at 23:37:18 UTC from IEEE Xplore. Restrictions apply.