Power amplifier having enhanced swing cascode architecture
View Patent ↗A Radio Frequency (RF) power amplifier includes a transconductance stage, an AC coupling element, and a cascode stage. The transconductance stage is adapted to receive an input RF voltage signal and to produce an output RF current signal. The cascode stage is adapted to receive an input RF current signal and to produce an output RF voltage signal. The AC coupling element couples between the transconductance stage and the cascode stage and is operable to AC couple the output RF current signal of the transconductance stage as the input RF current signal of the cascode stage.
1. A Radio Frequency (RF) power amplifier comprising:
a differential transconductance stage adapted to receive a differential input RF voltage signal and to produce a differential output RF current signal;
a differential cascode stage adapted to receive a differential input RF current signal and to produce a differential output RF voltage signal; and
a differential AC coupling element coupled between the differential transconductance stage and the differential cascode stage and operable to AC couple the differential output RF current signal of the differential transconductance stage as the differential input RF current signal of the differential cascode stage.
2. The RF power amplifier of claim 1 , wherein each portion of the differential trans conductance stage comprises a linear transconductance element and a circuit element that together couple between a transconductance stage voltage supply and a ground.
3. The RE power amplifier of claim 2 , wherein of the differential transconductance stage:
each linear transconductance element comprises a transistor; and
each circuit element comprises an inductor.
4. The RF power amplifier of claim 1 , wherein each portion of the differential cascode stage comprises a series combination of a first inductor, source and drain terminals of a transistor, and a second inductor biased between a cascode stage voltage supply and a ground.
5. The RF power amplifier of claim 4 , wherein of the differential cascode stage, gates of each transistor are adapted to receive a controllable cascode bias voltage.
6. The RF power amplifier of claim 1 , wherein the differential transconductance stage and the differential cascade stage are powered at differing voltage supply levels.
7. The RF power amplifier of claim 1 , wherein the differential transconductance stage and the differential cascode stage are powered at a common voltage supply level.
8. The RF power amplifier of claim 1 , wherein each portion of the differential AC coupling element comprises a capacitor.
9. A method for amplifying a differential Radio Frequency (RF) signal comprising:
receiving a differential input RF voltage signal;
producing a differential output RF current signal based upon the differential input RF voltage signal using a differential transconductance stage;
AC coupling the differential output RF current signal as a differential input RF current signal to a differential cascode stage; and
producing a differential output RF voltage signal based upon the differential input RF current signal using a differential cascade stage.
10. The method of claim 9 , further comprising controlling a plurality of cascode bias voltages applied to the differential cascode stage.
11. The method of claim 9 , further comprising powering the differential transconductance stage and the differential cascade stage at differing voltage supply levels.
12. The method of claim 9 , further comprising powering the differential trans conductance stage and the differential cascade stage at a common voltage supply level.