E-band Transmitter Module Using a LCP Substrate - PIERS

Progress In Electromagnetics Research Symposium Proceedings, KL, MALAYSIA, March 27–30, 2012 1245

E-band Transmitter Module Using a LCP Substrate Young Chul Lee1 , Salizul Jaafar2 , Mohd. Fadzil Amiruddin2 , Suhandi Bujang2 , and Azzemi Ariffin2 1

Division of Marine Electronics and Communication Engineering Mokpo National Maritime University (MMU), Korea 2 System Technology, Telecom Malaysia Research & Development (TMR&D), Korea

Abstract— We present a 70 GHz Amplitude-Shift-Keying (ASK) transmitter module based on a system-on-package (SoP) technology using a liquid-crystal polymer (LCP) substrate for pointto-point wireless communication applications. Four monolithic microwave integrated circuits (MMICs), which are two frequency multipliers (MTLs), a driver amplifier (DA), and a ASK modulator, are used in the metal-backed LCP SoP module. Its size is 15.8 × 13.0 × 2.2 mm3 and its output power is −8.2 dBm at the local oscillation (LO) frequency of 12.48 GHz with 5.0 dBm, intermediate frequency (IF) of 20 MHz with ±25 mV and −0.7 V for off-set. 1. INTRODUCTION

Recently, because various high-speed data services such as 3.5G, 4G mobile communications, WiMax, etc. have progressed, the demands for high-capacity and -speed Ethernet networks have rapidly increased. High-capacity and speed networks can be implemented by using a millimeter wave (mm-wave) [1, 2], free space optical (FOS) [3], and fiber-optic network. In the case of FOS and fiber-optic communications, there are some limitations related to natural environment such as fog and rain and install expense. The high-capacity and speed wireless communications using mm-waves are a competitive alternative in respects of install time, cost, and natural environments, compared to the FOS and fiber-optic communications, short-range wireless communication applications. Commercial wireless point-to-point (PtP) links using a 60, 70, and 80 GHz band have developed for high-capacity and -speed Ethernet applications. However, because of additional propagation loss due to oxygen absorption at 60 GHz [4], 60 GHz PtP links are limited. Contrarily, in the case of E-band such as 70 and 80 GHz bands, longer link range and higher speed because of no oxygen absorption and more available bandwidth, respectively, can be offered [5]. To commercially realize these E-band link applications, a cost effective radio module is indispensable. The system-on-package (SoP) approach [6–9] using a low-temperature co-fired ceramic (LTCC) and liquid-crystal polymer (LCP) technology has been demonstrated to be suitable technology integrating active and passive circuits into a compact single substrate. Although the LTCC technology has provided very dense multilayer integration and excellent electrical performance, the design at mm-wave bands has become challenging due to limitation of design rules [10]. The LCP’s low loss (tan δ = 0.002 ∼ 0.004), low cost, low water absorption (0.04%) and low permittivity (εr = 2.9 ∼ 3.0) make very attractive for RF and mm-wave SoP applications. In this paper, a 70 GHz ASK Tx LCP SoP module has been presented for wireless gigabit PtP applications. Four GaAs MMIC chips and DC bias components has been fully integrated into the metal backed LCP substrate. The implemented Tx LCP SoP module is as small as 15.8 × 13.0 × 2.2 mm3 . The measured Tx performance is presented. 2. DESIGN AND FABRICATION OF AN ASK TRANSMITTER LCP MODULE

The radio systems with an ASK modulation technique [11] have been widely used for mm-wave applications because of its simplicity and power efficiency. And also, in the case of an ASK noncoherent de-modulation technique by using a simple envelope detector, there are no needs of a coherent LO signal. Especially, the ASK modulation has been investigated and utilized for gigabit transmitting systems using millimeter-wave bands whose analog-digital converter (ADC) is hard to be implemented. A block diagram of a 70 GHz ASK transmitter (Tx) is shown in Fig. 1. Its carrier center frequency is 72.1 GHz, and also its bandwidth is 2.2 GHz. The Tx part consists of a up-converting mixer, and three commercially available GaAs MMICs: two frequency multipliers (MTLs, 2X and 3X) and a driving amplifier (DA). The external local oscillation (LO) signal of 12.017 GHz for the Tx is multiplied by 6 times and amplified in order to drive the up-converting mixer.

PIERS Proceedings, Kuala Lumpur, MALAYSIA, March 27–30, 2012

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In order to integrate the designed 70 GHz ASK Tx into the LCP SoP single module, the metal-backed LCP substrate incorporating a WR12 waveguide is used. The probe-type WR12to-microstrip transition is designed on the LCP substrate. The cavities to mount MMICs were formed in the LCP substrate. The metal lines on the LCP were gold-plated. In order to compensate parasitics due to wire-bonding between the MMIC and LCP board, microstrip-type matching circuits were designed on the LCP substrate. Fig. 2 shows the vertical structure of the 70 GHz Tx LCP SoP module and the fabricated one. This module was designed for testing using GSG probe tips. A GSG-type IF, LO, and RF port were designed. For effective analysis of the ASK Tx module, the two blocks, MTL (2x and 3x) and DA, were also designed. The designed 70 GHz ASK Tx module was fabricated in the commercial foundry. The whole size of the LCP module is 15.8 × 13.0 × 2.2 mm3 as shown in Fig. 2(b).

Figure 1: Block diagram of a 70 GHz ASK transmitter for point-to-point wireless communication systems.

(b) Fabricated module (15.8x13.0x2.2 mm 3 )

(a) Vertical structure

Figure 2: Block diagram of a 70 GHz ASK transmitter for point-to-point wireless communication systems. -20 -24.93 -30 -40

P o we r [d Bm ]

-50 -60 -70 -80 -90 -100 74.877

74.878

74.879

74.880

74.881

74.882

74.883

Fre q . [GHz]

Figure 3: Measured spectrum results of the fabricated MTL block [Inset: the fabricated MTL block consisting of the 2X and 3X MTL].

Figure 4: Measured s-parameters characteristics of the fabricated DA module [Inset: the fabricated DA block].

Progress In Electromagnetics Research Symposium Proceedings, KL, MALAYSIA, March 27–30, 2012 1247 -3.0E+01

-4.0E+01

P o u t [d Bm ]

-5.0E+01

-6.0E+01

-7.0E+01

-8.0E+01

9.0E+01 74.80 74.82 74.84 74.86 74.88 74.90 74.92 74.94 74.96 74.98

Fre q . [GHz]

Figure 5: Measured spectrum characteristics of the fabricated ASK Tx LCP SoP module (The attenuator with the loss of 24.8 dB was connected to the RF port).

3. MEASURED RESULTS

The frequency spectrum characteristics of the fabricated MTL block consisting of the 2X and 3X MTL MMIC were characterized in Fig. 3. This figure shows clearly that an input frequency of 12.48 GHz with a power of 5.22 dBm was normally multiplied to 74.88 GHz (by 6 times). The measured output power was −10.93 dBm considering an attenuator with -14dB loss. The 2X MTL dissipated 83 mA at 2.5 V. In order to drive the double-balanced mixer MMIC integrated in the Tx, the LO signal from the MTL block should be amplified up to 14 dBm by using the DA. Fig. 4 shows the characteristics of the fabricated DA block. At 74 GHz, a S11 and S22 are lower than −10 dB and an insertion loss of 25 dB is achieved. Total current of 87 mA at Vg = 0 V and Vd = 4 V was dissipated. Figure 5 shows the measured RF spectrum of the fabricated ASK Tx LCP SoP module. For ASK modulation, the IF signal generated by a pulse pattern generator (Agilent Tech. 81110A) was used to the IF port of the ASK Tx module and also an off-set voltage of −0.7 V was forced to it. At the LO frequency of 74.9 GHz with the power of 5 dBm and IF of 20 MHz with ±50 mV, the output power (Pout ) of −8.2 dBm is achieved. 4. CONCLUSION

In this paper, the 70 GHz ASK transmitter SoP module using the metal backed LCP substrate has been presented for point-to-point wireless communication applications. The whole Tx circuitry including a ASK modulator, two frequency multipliers, a driving amplifier, and all DC bias components are fully integrated into the single LCP substrate. Its size is 15.8 × 13.0 × 2.2 mm3 and its output power is −8.2 dBm at the LO frequency of 12.483 GHz with 5.0 dBm, intermediate frequency (IF) of 20 MHz with ±25 mV and −0.7 V for off-set. REFERENCES

1. Smulders, P., “Exploiting the 60 GHz band for local wireless multimedia access: Prospects and future directions,” IEEE Commun. Magzine, 140–147, 2002. 2. Ohata, K., K. Maruhashi, M. Ito, S. Kishimoto, K. Ikuina, T. Hashiguchi, K. Ikeda, and N. Takahashi, “1.25 Gbps wireless Gigabit Ethernet link at 60 GHz-band,” IEEE MTT-S International Microwave Symposium, 373–376, 2003. 3. Kamalakis, T., et al., “Hybrid free space optical/millimeter wave outdoor links for broad-band wireless access networks,” 18th Annual IEEE Symposium on PIMRC, 2007. 4. Marcus, M. and B. Pattan, “Millimeter-wave propagation: Spectrum management implications,” IEEE Microwave Magazine, 54–62, 2005. 5. Sevimli, O., V. Dyadyuk, D. Abbott, J. Bunton, R. Kendall, L. Stokes, M. Shen, and S. Smith, “Multi-gigabit wireless link development,” Auswireless Conference, 2006. 6. Lee, Y. C., T.-W. Kim, A. B. Ariffin, and N.-G. Myoung, “60-GHz amplitude shift- keying receiver ltcc system-on-package module,” Microwave and Optical Technology Letters, Vol. 53, No. 4, 758–761, 2011.

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7. Jung, D. Y., W.-I. Chang, K. C. Eun, and C. S. Park, “60-GHz system-on-package transmitter integrating sub-harmonic frequency amplitude shift-keying modulator,” IEEE Transactions on Microwave Theory and Techniques, Vol. 55, No. 8, 1786–1793, 2007. 8. Aihara, K., M. J. Chen, and A.-V. Pham, “Development of thin-film liquid-crystal-polymer surface-mount packages for Ka-band applications,” IEEE Transaction on Microwave Theory and Techniques, Vol. 56, No. 9, 2111–2117, 2008. 9. Aihara, K., A. Pham, D. Zeeb, T. Flack, and E. Stoneham, “Development of multi-layer liquid crystal polymer Ka-band receiver modules,” Asia-Pacific Microwave Conference (APMC), 2007. 10. Pinel, S., S. Sarkar, R. Bairavasubramanian, J.-H. Lee, M. Tentzeris, J. Papapolymerou, and J. Laskar, “Highly integrated LTCC and LCP millimeter wave functions for 3D-SOP high data rate wireless systems,” Electronic Components and Technology Conference, 764–768, 2005. 11. Tarusawa, Y., H. Ogawa, and T. Hirota, “A new constant resistance ASK modulator using double-sided MIC,” IEEE Transaction on Microwave Theory and Techniques, Vol. 35, No. 9, 819–822, 1987.