Yaw rate detection

hi!
I know gyros output voltage is not ratiometric but [ch305] want to detect turn angle around the yaw axis. [ch305] can find roll and pitch angel by accl.+gyro+ kalman but I have not been succesful about yaw angle detection yet. please help and idea!

I have arduino Diecimila board+ADXL330 accl.+ EPSON XV8100CB gyro

NOTE: I do not understand fully how to gyro work? For example [ch305] turn gyro so its output voltage increase and returns its zero bias value immadiately.Is this normal for gyro working or my gyro is damaged!

I do not understand fully how to gyro work?

Have you played with a toy gyro? When you rotate it you feel a resistance to that movement. That resistance you feel is translated into a voltage. If you stop moving it, you will stop feeling the restoring force and will stop producing a voltage. So yes it is working normally.

However, I don't know about your specific problem, does the gyro have three axis readout? Some only have two and I can't find a data sheet on line. Can you point me towards one?

Now [ch305] am sure my gyro is safe but [ch305] want to measure yaw angle for my IMU [ch305] measure roll and pitch with acc+gyro+kalman filter it gives a goog result. But as you know for yaw angle detection accelerometers can not be used. as a result of that I want to use magnetometer instead of accelerometer only for yaw axis. gyro+magnetometer+kalman. Is it useful for this application and can you advice me a magnetometer for better solution or another idea? Thanks...

There are not so much information about the gyro only these documents I have:
http://ndap3-net.ebz.epson.co.jp/w/www/PDFS/epdoc_qd.nsf/f5af260ddc5fb8ed49256a9c001d58b2/6c3c798debd98cfe492571f1000ff2dc/$FILE/XV-8100_E082.pdf

http://www.ineltro.ch/stream/de/prj/product/datasheet---0--0--0--19848.pdf