how about designing a Quad band PA in one die

There are two PA dies in Most Quad band PA(GSM850,GSM900,DCS,PCS) ,one for GSM850&GSM900,the other for DCS&PCS,How about design them in one die,select respective input and output matching networks by an analog switch?

i think it is two amps of cover the 850 and 900 band , and the other 1800 and 1900

khouly

There is an isolation issue that appears if combine the two dies in one.
Second harmonic of low band arrives on high band frequencies, and there would be no rejection of it up to the antenna connector.