4684.新型宽带面谐平衡混频器设计与性能的影响 毕业设计(论文)英文原文.doc

DESIGN AND PERFORMANCE OF A NOVEL BROADBAND UNIPLANAR BALANCEDSUBHARMONIC MIXERABSTRACT: A novel wideband uniplanar balanced subharmonic mixer is proposed and demonstrated. The mixer is based on the broadband tapered coplanar-waveguide (CPW) DC-block filter, and the in-phase and out-of-phase T-junctions are interconnected through a pair of quarter-wavelength slotlines. The fabricated subharmonic mixer has an RF bandwidth of more than one octave from 12 to 28GHz with a conversion loss ranging from 8.5 to 12.5 dB for LO signals from 6.1 to 14.1 GHz with a power level of 9.5 dBm. The measured LO-to-RF, LO-to-IF, and RF-to-IF isolations are better than 15.5, 34, and 26.6 dB, respectively. . 2005 Wiley Periodicals, Inc.Microwave Opt Technol Lett 44: 508 510, 2005; Published online in Wiley InterScience. DOI 10.1002/mop.20681Key words: balanced subharmonic mixer; broadband uniplanar technology; coplanar waveguide; slotline; microwave integrated circuits1. INTRODUCTIONUniplanar technology has received considerable attention with regard to low-cost and high-performance microwave integrated circuits (MICs) and microwave monolithic integrated circuits (MMICs), especially in the millimeter-wave range 13. This is due to the merits not requiring via holes for connecting circuit elements to the ground, elimination of the backside processes, simple realization of series and shunt circuit components, easy integration with solid-state devices and other lumped elements,and low sensitivity to substrate thickness 4. Furthermore, this technology allows flexible circuit design using mixed transmission lines such as coplanar waveguide (CPW), slotline, and coplanar stripline. Subharmonic mixing is very useful at millimeter wave frequencies due to the availability of low-cost lower-frequency local oscillators (LOs). Balanced subharmonic mixers have the advantages of the inherent LO-to-RF isolation and the reduction of LO noise and spurious signals 5.Recently, a few balanced subharmonic mixers using a uniplanar structure have been developed 6, 7. A subharmonic diode mixer using a uniplanar hybrid with a double-Y balun was proposed for low-cost broadband millimeter-wave transceiver design 6. The hybrid consists of a combination of a tapered slotline T-junction and a tapered CPW divider interconnected through a slotline ring. The conversion loss of the mixer is about 10 to 12 dB over a 2636-GHz RF bandwidth. A balanced subharmonically pumped diode mixer based on the modified slotline-to-CPW junction was also proposed 7. In this design, the hybrid was realized by the combination of twin-spiral CPW-to-slotline transition and modified slotline-to-CPW junction. The conversion loss varies from 10 to 12 dB when the RF signal is swept from 3 to 4 GHz and the IF frequency is 0.1 GHz. While these mixers are suitable for the realization of a compact uniplanar transceiver, they show relatively narrow bandwidth. In this paper, the design and measurement results of a uniplanar single balanced subharmonic mixer with broader bandwidth than that of conventional ones are presented. The proposed subharmonic mixer using CPW and slotline has also features of low conversion loss, small size, the ease of fabrication, and a simple structure for integrated microwave circuits.Figure1 Configuration of the proposed uniplanar balanced subharmonicmixerFigure2 Structure of the broadband tapered CPW DC-block filter2. SUBHARMONIC MIXER DESIGNThe configuration of the proposed broadband uniplanar balanced subharmonic mixer is shown in Figure 1. The circuit consists of a broadband tapered CPW DC-block filter, a CPW radial-line double stub, an in-phase CPW-slot T-junction, an out-of-phase tapered slotline T-junction, a half-wavelength circumference slotline ring, two anti-parallel Schottky diode pairs, and a CPW-to-slotline transition. Bonding wires are used at nonsymmetrical CPW discontinuities such as T-junctions to suppress the undesired coupled slotline mode by maintaining an equal potential on each side of the ground plane. The balanced subharmonic mixing is based on a uniplanar magic T, which is composed of an in-phase parallel T-junction and an out-of-phase series T-junction interconnected through a pair of quarter-wavelength slotlines at the LO center frequency. Since these T-junctions are frequency independent, the magic T has inherent LO-to-RF/IF isolation and broadband characteristics. The RF signal is applied to the diodes through the DC-block filter and the in-phase CPW-slot T-junction. For DC and IF blocking at the RF port, the tapered CPW DC-block filter proposed in 8 is used with a tapered CPW section. The centerspacing between the inner slots of the open-end series stub linearly varies for wide band operation, as shown in Figure 2. The bandwidth of the DC-block filter increases as the spacing W between the slots in the CPW is increased and the characteristic impedance of the CPW is decreased. The spacing W of 0.5 mm with 30_ characteristic impedance is used and the DC-block is interconnected with a 50_ CPW through 3-mm tapered CPW sections. The LO signal is fed to the diodes via a CPW-to-slotline transition and an out-of-phase slotline T-junction. The slotline T-junction splits the LO signal into two signals that are of equal amplitude and 180° out of phases on the slotlines. The tapered slotline provides a match from the 50_ slotline to the two diodes at the LO frequencies. The CPW-to-slotline transition, which employs a slotline radial stub, is used to transfer a 50_ CPW to a 50_ slotline. The radius of the radial stub is 2.9 mm and the radial stub angle is 90°. The measurements of the back-to-back connected transitions, formed using a pair of CPW-to-slotline transitions separated by 2-mm-long slotline, exhibit insertion loss of less than 0.8 dB and return loss of more than 15 dB over 515 GHz.Two anti-parallel Schottky diode pairs (Alpha DMK2308-000) areflip-chip mounted across the gaps of the slotline ring with a silver epoxy. The IF signal is extracted via a low-pass filter that employs a CPW radial-line double stub in order to provide an open circuit at the RF frequencies. A commercial microwave software package (Agilent ADS) is used to simulate and optimize the uniplanar structures and the subharmonic mixer by employing a harmonic balance analysis following the initial design.3. EXPERIMENTAL RESULTSTo verify the proposed design principle, a broadband tapered CPW DC-block filter and a uniplanar single balanced subharmonic mixer with a 16-GHz RF bandwidth centered at 20 GHz were fabricated and measured. The circuits were built on a 25-mil-thick alumina substrate with a dielectric constant of 9.9 using a standard thin-film process. The mixer dimensions are 0.635 mm. The manufactured DC-block filter is measured using an HP8510C network analyzer and a probe station with a line-reflect-match (LRM) calibration. Figure 3 shows the measured and simulated S-parameters of the fabricated DC-block filter and good agreement between two results is observed. The measurements show insertion loss less than 1.5 dB and return loss better than 10 dB over 1230GHz.The entire subharmonic mixer circuit is measured with respect to conversion loss and the RF-to-IF and LO-to-RF/IF isolations. Figure 4 shows the measured conversion loss and RF-to-IF isolation versus RF frequency for the LO signals from 6.1 to 14.1 GHz with a power level of 9.5 dBm and fixed IF frequency of 0.2 GHz.Over the RF frequency of 1228 GHz, the conversion loss is from .5 to 12.5 dB and the RF-to-IF isolation is better than 26.6dB.The conversion loss of the subharmonic mixer as a function of the LO power is shown in Figure 5. With the RF power level fixed at _10 dBm at 20 GHz and the LO at 10.1 GHz, the conversion lossbegins to saturate at around 8 dBm. The measured LO-to-RF and LO-to-IF isolations are shown in Figure 6. The LO-to-RF and LO-to-IF isolations are better than 15.5 and 34 dB for the LO frequency from 6.1 to 14.1 GHz, respectively.4. CONCLUSIONA broadband uniplanar balanced subharmonic mixer using CPW and slotline has been proposed and demonstrated. The fabricated subharmonic mixer has an RF bandwidth of more than one octave from 12 to 28 GHz with a conversion loss ranging from 8.5 to 12.5dB for the LO signals from 6.1 to 14.1 GHz with a power level of 9.5 dBm. The measured LO-to-RF, LO-to-IF, and RF-to-IF isolations are better than 15.5, 34, and 26.6 dB, respectively. The measurements of the tapered CPW DC-block filter show insertion loss of less than 0.8 dB and return loss of more than 15 dB over 1230 GHz. The proposed subharmonic mixer has the features of low conversion loss, small size, ease of fabrication, and a simple structure for integrated microwave and millimeter-wave circuits.REFERENCES1. I.J. Chen, H. Wang, and P. Hsu, A V-band quasi-optical GaAs HEMT monolithic integrated antenna and receiver front end, IEEE Trans Microwave Theory Tech 51 (2003), 24612468.2. K. Hettak, G.Y. Delisle, and L. Talbi, A 38-GHz integrated uniplanar subsystem for high-speed wireless broad-band multimedia systems, IEEE Trans Microwave Theory Tech 47 (1999), 935942.3. V. Trifunovic and B. Jokanovic, Review of printed Marchand and double Y baluns: Characteristics and application, IEEE Trans Microwave Theory Tech 42 (1994), 14541462.4. K.C. Gupta, R. Garg, and I.J. Bahl, Microstrip lines and slotlines, 2nd ed., Artech House, Norwood, MA, 1996.5. S.A. Maas, Microwave mixers, 2nd ed., Artech House, Norwood, MA,1992.6. H. Gu and K. Wu, A novel uniplanar balanced subharmonically pumped mixer for low-cost broadband millimeter-wave transceiver design, IEEE MTT-S Int Symp Dig (2000), Boston, MA, 635638.7. C.H. Wang, H. Wang, and C.H. Chen, A full-wave analysis model for uniplanar circuits with lumped elements, IEEE Trans Microwave Theory Tech 51 (2003), 207215.8. H. Gu, and K. Wu, Broadband uniplanar building blocks for monolithic and hybrid millimeter-wave integrated circuits, 30th Euro Microwave Conf, 2000, pp. 395398. 2005 Wiley Periodicals, Inc.All-Optical Mixer Based on Cross-AbsorptionModulation in Electroabsorption ModulatorJianjun Yu, Senior Member, IEEE, Zhensheng Jia, and Gee Kung Chang, Fellow, IEEEAbstractWe have proposed and experimentally demonstrated a novel method to realize nonlinear optical mixing based on crossabsorption modulation in an electroabsorption modulator. Our experimental results show that the local oscillator power and optical filtering play an important role on the receiver sensitivity of the up-conversion signal; furthermore, the wavelength span of larger than 20 nm for up-conversion signal can be obtained.Index Terms：Cross-absorption modulation, nonlinear optical mixer, radio-over-fiber, wavelength conversion.1.INTRODUCTIONPEOPLE are paying more attention to the application of radio-over-fiber (ROF) for broad-band wireless access systems recently which are capable of providing the anticipated demand for future broad-band interactive services. To reduce the complexity of the architecture and meet more end-users between central station and base station (BS) at the same time, a solution to seamlessly integrate the wavelength-division-multiplexing (WDM) or WDM passive optical network transport systems with ROF access system to take full advantage of its ultrabandwidth characteristics is desirable. For a successful implementation of WDM ROF systems, all-optical up-conversion for WDM signals is the key issue to be solved 13. Currently, all-optical up-conversion based on nonlinear effects in nonlinear fiber or waveguide device needs high optical power and is polarization sensitivity. Although the polarization sensitivity can be reduced by adding some optical components, it will greatly increase the configuration complexity. While based on cross-gain modulation in semiconductor optical amplifier (SOA) to realize all-optical mixing, the modulation frequency of the SOA usually is narrow, which is very difficult to realize data signal to mix with high frequency local oscillator (LO) signal. Among them, cross-absorption modulation (XAM) in an electroabsorption modulator (EAM) could be one of the most promising ways to realize all-optical signal up-conversion or mixing similar to its wavelength conversion principle at high bit rate 47; the main difference from wavelength conversion is that the modulated data signal will be used to replace the CW lightwave. Comparing it with other existing all-optical mixing methods, this scheme has some unique advantages such as lowpower consumption, compact size, polarization insensitivity, easy integration with other devices, and higher speed operation due to EAM inherent characteristics 7. Here, we report 2.5-Gb/s data signal mixed with a 40-GHz LO signal based on XAM in an EAM for the first time.We investigate the up-conversion performance at different LO power and different wavelength span. Vestigial sideband (VSB) is used to reduce the carrier-to-sideband signal ratio (CSR) 8 and increase the receiver sensitivity.Fig. 1. Experimental setup. LNM: LN-modulator. TL: tunable laser. OC: optical coupler. PS: phase shifter. PD: photodiode. EA: electrical amplifier. LPF: low-pass filter. RX: receiver. TA: tunable attenuator. The preamplifier noise figure is 6 dB.II. EXPERIMENTAL SETUP AND RESULTSThe experimental setup is shown in Fig. 1. An EAM (Cy- Optics model: EAM 40) with 3-dB bandwidth of 32-GHz fiber-to-fiber insertion loss of 8 dB and polarization sensitivity lower than 1 dB was used to realize data signal up-conversion. A 2.5-Gb/s data signal was generated from a tunable laser at 1560.4 nm modulated by a LiNbO MachZehnder modulator driven by 2.5-Gb/s pseudorandom bit sequence electrical signal with a word length of 2-1. To generate a 40-GHz optical LO signal, we used carrier-suppressed return-to-zero signal, which is realized by driving a dual-arm LiNbO MachZehnder modulator biased at V with two complementary 20-GHz sinusoidal waveforms. The carrier suppression ratio is larger than 25 dB, the repetitive frequency of the generated LO optical signal is 40 GHz, and the duty cycle of the LO is 0.6. The optical LO signal was amplified before the LO signal and the data signal were injected into the EAM. The up-conversion signal was separated from the LO signal by using a WDM filter. Then an erbium-doped fiber amplifier (EDFA) was used to boost optical power before a tunable optical filter (TOF1) was employed to suppress amplified spontaneous emission (ASE) noise and realize VSB filtering. The up-conversion signal after TOF1 was preamplified by a regular EDFA with a gain of 30 dB at small signal. In this experiment, two types of TOF1 with different bandwidth, 0.5 or 1.4 nm, were employed. After amplification, the amplified up-conversion signal was filtered