Fully differential CMOS power amplifier
AssigneeItaltel Societa Italiana Telecomunicazione S.p.A.
InventorsFranco Maloberti, Giuseppe Palmisano, Luigi Sforzini, Giuseppe Gazzoli
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Abstract
A fully differential CMOS power amplifier having a folded-cascode input stage, an AB class output stage, a first common mode feedback circuit that stabilizes the input stage, and a second common mode feedback circuit that stabilizes the output stage. Each feedback circuit feeds back to an internal node of its particular stage. The power amplifier also includes a power dissipation reduction circuit that shuts down the power amplifier's output first and then the rest of the power amplifier, when the power amplifier is idle for a certain period. This reduction circuit activates the power amplifier in the reverse order.
Claims13
A substantially fully differential CMOS power amplifier having an output comprising:
- a folded-cascode input stage having an input including a plurality of input terminals and having an output including a plurality of output terminals;
- an AB class output, having an input including a plurality of input terminals connected to the output terminals of said input stage, respectively, and having an output comprising a plurality of output terminals;
- a first common mode feedback circuit having an input connected to the output of said input stage, and having an output including a plurality of output terminals connected to an internal node of said input stage;
- a second common mode feedback circuit having plural inputs and outputs, connected between the plural outputs of said output stage and at least two internal low impedance junctions of said output stage, said second common mode feedback circuit reducing a common mode signal at the output of said power amplifier by injection of plural feedback currents commensurate in number with said at least two junctions to which said second common mode feedback means is connected.
Dependencies are inferred from the claim text.