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This paper provides a comprehensive methodology for accurate analysis and design of miniaturized radio frequency (RF) surface acoustic wave (SAW) duplexer package. Full-wave analysis based on the three dimensional (3-D) finite element method (FEM) is applied to get the package model. The die model. is obtained by combining the parasitics and acoust...
Contexts in source publication
Context 1
... cas- caded T-network is used for transmitter path and a Pi- network is used to implement the receiver path of the du- plexer [15]. The die is mounted using conductive epoxy to ensure ground on the backside of the die. The connections between the die and package are made using gold bonding wires. The schematic of the duplexer assembly is shown in Fig. ...
Context 2
... Af- ter combining the results of the package and die in ADS, we can change the positions of bonding wires to investigate the influence of the bonding wires. For the bonding wire scheme shown in Fig. 14, the bonding wire positions are changed for the Rx ground, and two more bonding wires are added compared with the bonding wire scheme shown in Fig. 3. The inductance to ground for the Rx channel is reduced. The isolation can be improved from 1.65 to 1.8 GHz and 4.6 dB improvement is achieved at 1.75 GHz as shown in Fig. 15. The solid line shows the new results with the new bonding wire scheme shown in Fig. 14. The dashed line shows the simulation results shown in Fig. 11. ...
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Citations
... This intrinsic problem can be overcome with the use of miniaturized surface acoustic wave (SAW) duplexers [4], utilizing a frequency division duplex (FDD) scheme. This approach occupies a very small footprint, but its complex architecture makes it difficult to design and fabricate for arbitrary frequency bands. ...
Constant development of new wireless standards increases the demand for more radiating elements in compact end-user platforms. A decrease in antenna separation gives rise to increased antenna coupling, resulting in a reduction of the signal-to-interference-plus-noise ratio (SINR) between transmitter and receiver. This letter proposes a decoupling network that provides dual-band port isolation for a pair of distinct antennas. A prototype has been fabricated to verify the theory.
... The modeling approach is valid only if the size of the package is sufficiently smaller than the wavelength of the electromagnetic wave. At higher frequencies, however, more rigorous electromagnetic analysis is necessary [182, 202, 203]. In the numerical computation of capacitance and impedance matrices, the charge density and current, respectively, are represented using pulse functions. ...
This dissertation discusses numerical simulations of microwave acoustic resonators and bandpass filters employed in wireless telecommunication systems. In the first part of the dissertation, tailored finite element method (FEM) software with efficient numerical techniques is implemented and applied in the modeling of thin-film bulk-acoustic wave resonators (FBARs). Simulations with 3D FEM models of FBARs are carried out to investigate the effect of the electrode shape on the spurious resonances that often are present in the electrical response. The modeling results are validated through comparison of simulated and measured mechanical vibration amplitudes. The usability of the FEM tool is further demonstrated in simulations of a resonator design that features a clean electrical frequency response, free of spurious resonance peaks caused by anharmonic modes. Additionally, a method is proposed for determination of the elastic constants of a piezoelectric thin-film material. The technique is based on fitting of the computed dispersion curves of Lamb-wave modes to those measured from an FBAR using a scanning laser interferometer. In the second part of this dissertation, numerical simulations are used to study propagation properties of longitudinal leaky surface acoustic wave (LLSAW) mode under periodic electrode array on YZ-cut lithium niobate (LN). A combined FEM/boundary element method is employed to compute the electric admittance of one-port synchronous LLSAW resonators. Simulations and experiments are used to derive the dependence of the resonator resonance frequencies and Q values on the electrode dimensions. Ladder-type bandpass filters exploiting the LLSAW mode are implemented on YZ-cut LN in the frequency range from 2.5 GHz to 5.2 GHz, with fundamental mode LLSAW resonators as building blocks. The results demonstrate that the high phase velocity of the LLSAW mode on YZ-cut LN allows inexpensive fabrication of wide-band, low-loss filters up to 5 GHz using conventional optical lithography. The third topic considered is comprehensive modeling of a SAW duplexer, including electromagnetic modeling of the ceramic package. The parasitic capacitive and inductive couplings in the package are obtained using rigorous computation, allowing one to estimate the package effects on the duplexer performance. TKK dissertations, ISSN 1795-4584; 5
... We can easily analyze the influence of each part based on the methodology developed in this dissertation. For the KPCS duplexer package, we have found several novel methods to improve the isolation at the Tx stopband [25]. ...
This dissertation provides a comprehensive methodology for accurate analysis and design of miniaturized radio frequency (RF) surface acoustic wave (SAW) duplexer package. Full-wave analysis based on the three dimensional (3-D) finite element method (FEM) is successfully applied to model the package. The die model is obtained by combining the acoustics and die busbars parasitics models. The acoustics model is obtained using the coupling-of-models (COM) technique. The die busbars, bonding wires and printed circuit board (PCB) are modeled using full-wave analysis. After that, the models of package, die, and bonding wires are assembled together to get the total response. To take into account the mutual couplings, the methodology is extended to model the package, die busbars, and bonding wires together. The advantages and disadvantages of the methodology are also discussed. Based on the methodology, the Korea personal communication system (KPCS) duplexer is analyzed and designed. The isolation of KPCS duplexer package is significantly improved by redesigning inner ground plane, bonding wire scheme and ground via. A KPCS duplexer package is designed and excellent transmitter to receiver isolation in the transmission band is achieved. Simulation and measurement results are compared, and excellent agreement is found. Although we focus on investigating the methods to improve the isolation, the passband performance is also improved. The methodology is also successfully used for flip chip duplexer. The simulation results from our assembling method match the measurement results very well. Optimization method is applied to improve the transmit band isolation. With the new package and die design, the transmit band isolation can be improved from -53.6 dB to -65.2 dB. Based on the new package, the effect of the Rx ground trace on the isolation is investigated and the transmit band isolation can achieve -67.3 dB with the modification of the Rx ground trace. The technique developed in this dissertation reduces the design cycle time greatly and can be applied to various RF SAW device packages.
Currently, there are two types of CSP packaging techniques: Flip-chip CSP (FC-CSP) [1] and Wafer-level CSP packaging (WLCSP) [2, 3]. FC packaging technology has been in use for over 40 years. It was first introduced by IBM in the 1970s and was subsequently adopted by other chip makers. The main advantage of FC-CSP packaging is its small size. Although there is no definite rule for how small the package should be, a typical FC-CSP packaged device is 50–100% larger than its original die (chip) size. It is a significant improvement from the traditional wire-bonding-based (SMD and QFN) packaging technologies [4].
In full-duplex radio communication systems like e-UTRAN, CDMA-2000, the radio transmitter (Tx) is active at the same time as the radio receiver (Rx). The Tx and the Rx will be using separate dedicated frequency bands and the Tx-Rx isolation is ensured by duplex filters. However, agile duplexers required for multiband operation are almost nonexistent while dedicating a bank of narrowband filters is bulky and incurs considerable switching losses. In this paper, we propose an approach that dramatically reduces the complexity of the RF frontend, first by replacing the duplex filter with a spatial filter and second, by codesigning the filtering antennas and the RF frontend. The spatial filter is synthesized by equipping the Tx with redundant antennas. By properly weighting the Tx antennas, the Tx signal is selectively attenuated in the Rx direction. The spatial filter can be tuned to different frequency bands as long as the antennas are made tunable. Moreover, the spatial filter may directly benefit from the balanced architecture of the power amplifiers (PAs) thus reducing the total system complexity and insertion loss. Finally, simulation and initial measurement results are provided in a challenging low-frequency band, serving as a proof-of-concept.
Different geographies and localities around the world have adopted various wireless interface standards for mobile communications. As a result roaming users will require multiple handsets with multiple standards and multiple band capabilities. Triple-band hand sets are currently offered for high end users. In the future quad-band handsets including GSM 850 will become common in the market. This trend will continue. The addition of third generation functionality to second generation platforms will be even more difficult and complex. The radio handset should be able to use the same hardware for communications anywhere in the world. Therefore users will require small low cost terminals with multimode/ multi-band capability. The software radio concept has been developed to address these challenges. The replacement of fixed frequency components in the front end of the software radio is one of the key architectural changes required. The duplexer is one such component. Since duplexing filters are not normally tuneable, each band requires a separate duplexer in a multi-band system. The duplexers are passive devices (ceramic or SAW) and multiple duplexers lead to a dramatic increase in terminal cost and size. Abstract Adaptive Duplexer for Software Radio iv This thesis proposes a new adaptive duplexer architecture to reduce/eliminate the multiple duplexer problem in software radio. This technique is based on combining a low isolation device with an adaptive double loop cancelling scheme. The proposed double loop cancellation provides the required transmitter leakage and transmitter noise isolation over wideband using a delay element and an adjustable vector attenuator in each cancellation path. This thesis analyses the double loop cancellation technique. The cancellation path delay constraints are derived for coefficients with limited adjustment range in the cancellation paths. A linear relationship between the bandwidth and the achievable cancellation level is obtained. It is shown that the residual signal power is proportional to the square of the duplexing frequency. It is concluded that the delays in the cancellation paths should be chosen to straddle the expected range variation of the delay in the main path, predominantly caused by variations in antenna matching. The new algorithm uses a single cost function to achieve simultaneous cancellation in both the transmit band and the receive band. A direct conversion receiver architecture was chosen for the hardware prototype, since it is more suitable for multi-band systems. Alternate structures are also possible. A prototype of the adaptive duplexer using a 20dB circulator and a single loop cancelling technique was designed and implemented. It achieved a total Tx leakage cancellation of 69dB at 2GHz with 45MHz duplexing frequency. However it was not possible to simultaneously cancel the transmitter noise in the receiver band. The original prototype was extended to include the second loop. The achieved isolation between the transmit and the receive signals and the achieved reduction of the transmitter noise in the receiver band were 66.8dB and 58dB respectively. These results were obtained over 5MHz bandwidth and using a 190MHz duplexing frequency. The performance is more than adequate for W-CDMA applications. Lowering the duplexing frequency improves the cancellation bandwidth and so the scheme performs better with other standards, such as IS-95 (CDMA), using 45MHz duplexing offset.
A systematic approach to matching an arbitrary number of bulk acoustic wave or surface acoustic wave filters is proposed. The filters can be modeled as capacitor networks at frequencies above and below their passbands. The generic matching network consists of a single shunt inductor (or a transmission line) and series capacitors in front of each filter.
We describe a successful approach using commercial microwave software to modeling of the full RF filter layout including all electrodes of interdigital transducers and gratings. We use IE3D, a MOM based software by Zeland, to model the imported layout and we use the COM method to describe the acoustic properties of the elements. We benefit from the useful meshing capabilities of IE3D in order to obtain moderate size of the problems intended for solving with ordinary PC in reasonable time. We take special care to define properly ports for combining acoustic responses obtained from carefully fitted experimental COM parameters. With this procedure we are able to predict automatically some very important features of electromagnetic interactions within electrodes used for acoustical excitation, such as coupling between transducers in DMS structures. We describe an example of a two-port resonator with a detailed comparison of all experimental and modeled responses. This work opens the way to a further reduction of uncertainty in RF filter design.
