Naoko Kamogawa

High isolation SAW antenna duplexer modules

Optimized phase shifter conditions for SAW antenna duplexer modules at not 50 ohm cases have been analytically provided to achieve desired isolation performances. In order to confirm the prediction, obtained optimum condition are applied to two cases. In the EGSM/DCS dual band SAW antenna duplexer modules case, impedances of low noise amplifier connecting the Rx ports are not 50 ohm when the amplifier are off state at transmitter period. We propose a optimized phase shifter circuit for EGSM and DCS Rx output ports using the equation. In Japanese cdmaOne duplexer case, we also propose an optimized phase shifter circuit for the transmitter circuit between Rx band trap and transmitter top filter block. The predictions are verified by the experiments.

Saw duplexer design for WCDMA system

Some relations between sensitivity performances and duplexer performances (losses, isolations between Tx and Rx terminals) are obtained. We simulate system noise figure levels from duplexer performances and low noise amplifier parameters by using a nonlinear NF model at the viewpoint of a system design.

Study of high isolation techniques for surface acoustic wave duplexer modules

The isolation characteristics between transmitter and receiver ports for surface acoustic wave (SAW) antenna duplexer modules are studied. Three new techniques are developed to achieve the desired isolation performances in this study. Optimized phase shifter conditions are solved analytically. An improved switching circuit is proposed for cancellation of the inductive element of a pin-diode. A design rule of distance between two lines for SAW antenna duplexer modules is also proposed. The obtained condition and circuit are applied to an extended global system for mobile communication/digital cellular system (EGSM/DCS) dual-band and an extended global system for mobile communication/digital cellular system/personal communication system (EGSM/DCS/PCS) triple-band SAW antenna duplexer modules. Sufficiently high isolation characteristics are obtained.

Miniature SAW duplexers with high power capability

Miniature SAW duplexers with high power capability corresponding to future GSM power regulation have been reported. We applied an improved cascade resonator structure to the duplexer in order to equalize power density on substrate. Power durability of the developed duplexers is verified by an experiment under the condition of 3/8 duty mode operation corresponding to future regulation. Furthermore, we reduce the coplanarity of the duplexer using a partial metalized patterning on the back of the base board. A 14.8/spl times/8.0/spl times/1.8 mm dimension structure and a 80 micron (80 micron improvement as compared with conventional structure) typical coplanarity is obtained for the duplexer.

Automatic design procedure using circuit composition technique for SAW devices

A fully comprehensive electrical admittance matrix composition technique including the effects of residual electrical elements (capacitance, inductance and resistance) will be reported corresponding the various kind of the devices. An automatic design technique based on the optimization method is applied using the above composition routine. The automatic design procedure determines the parameters for SAW Filter elements and the external circuit element. It is possible that the procedure perform using measured admittance matrix elements. In order to verify the technique dual band filters and duplexers for digital mobile terminals were designed using the above procedure. The performance of these devices was found to be in good agreement with the design predictions.

High sidelobe rejection and miniature SAW filters using unidirectional and cascaded structures

A new type of SAW device has been proposed which composes a group type unidirectional technique and cascaded interdigital transducer (IDT) structure to achieve the desired performance without gratings and external phase shifters. In order to confirm the prediction, simulations and experiments are carried out. We select the equivalent circuit model and circuit composition procedure as a simulation technique. The predictions are verified by the simulations and the experiments. The structure is applied to a ring-type filter which is mounted in a 3 mm square package. The high sidelobe rejection and miniature performance of the filter are evaluated.

Automatic design technique based on nonlinear optimization for SAW devices

An improved automatic design technique based on nonlinear optimization method will be reported. The number of interdigital transducer (IDT) electrodes are treated as continuous function vector with the other design parameters, the IDT position, the IDT aperture and the external element constants etc. The procedure is applied to the interstage filter for digital mobile terminals which consists of two different substrates. We also apply the technique to high performance SAW antenna duplexers for digital mobile terminals and miniature SAW IF filters for automatic electrical toll collection systems. The performance of these devices is found to be in good agreement with the design predictions.

Study of Electrostatic Discharge Durability for Surface Acoustic Wave Module

The electrostatic discharge (ESD) characteristics of surface acoustic wave (SAW) antenna duplexer modules are studied. We have researched the main spectrum of ESD at first. Using the result showing that the main ESD response has a 200 to 250 MHz spectrum, three new techniques for an improved circuit and one new technique for an improved SAW package are developed to achieve the desired ESD durability in this study. A high-pass filter (Q) circuit is proposed in order to suppress the 200 to 250 MHz spectrum. A large capacitance voltage control (Cv) circuit is proposed for suppressing the minus pulse ESD signal. A low impedance transmitter (Tx) port circuit (L) near 200 to 250 MHz is proposed for suppressing the plus pulse ESD signal. A high-pressure-sealing SAW package is proposed to improve SAW device ESD durability. The obtained circuits and methods are applied to an extended global system for mobile communication/digital cellular system/personal communication system (EGSM/DCS/PCS) triple-band SAW antenna duplexer modules. A sufficiently high ESD durability is obtained consequently.

High isolation techniques for SAW duplexer modules

Isolation characteristics between transmitter and receiver ports for SAW antenna duplexer modules are studied in this paper. Two techniques for high isolation are presented. Optimized phase shifter conditions for SAW antenna duplexer modules at not 50 ohm cases have been analytically provided to achieve desired isolation performances. And switching circuit is proposed for high isolation characteristics. In order to confirm the prediction, obtained optimum phase condition and proposed circuit are applied to EGSM/DCS/ PCS triple band, SAW antenna duplexer modules.