Transformer Structures For A Power Amplifier (PA)

Abstract

In one embodiment, the present invention includes a transformer formed on a semiconductor die. Such transformer may have multiple coils, including first and second coils. Each coil may have segments that in turn are formed on a corresponding metal layer of the semiconductor die. The segments of a given coil are coupled to each other, and the first and second coils can be interdigitated with each other.

1 .- 8 . (canceled) 
     
     
         9 . A power amplifier comprising:
 a first gain stage to receive a first input signal and to amplify the first input signal and output a first amplified signal;   a second gain stage to receive a second input signal and to amplify the second input signal and output a second amplified signal; and   a transformer having a first coil to receive the first amplified signal, a second coil to receive the second amplified signal, and a third coil to output at least one of the first and second amplified signals to an output load.   
     
     
         10 . The power amplifier of  claim 9 , wherein the first, second and third coils are commonly coupled. 
     
     
         11 . The power amplifier of  claim 10 , further comprising a first tuning capacitance coupled in parallel to the first coil and a second tuning capacitance coupled in parallel to the second coil. 
     
     
         12 . The power amplifier of  claim 11 , wherein the second gain stage is to be placed into a high impedance state when inactive, and the second tuning capacitance is to maintain tuning of the second coil. 
     
     
         13 . The power amplifier of  claim 12 , further comprising an impedance transformation network coupled between the second gain stage and the second coil, wherein the impedance transformation network includes at least one capacitor and at least one inductor. 
     
     
         14 . The power amplifier of  claim 10 , wherein the first coil is formed on a first metal layer of a semiconductor die, the second coil is formed on a second metal layer of the semiconductor die, and the third coil is formed on a third metal layer of the semiconductor die. 
     
     
         15 . The power amplifier of  claim 14 , wherein the first gain stage corresponds to a higher power path and the second gain stage corresponds to a lower power path. 
     
     
         16 - 20 . (canceled)