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US 6,639,464 B2Granted
Composite amplifier
AssigneeLefonaktiebolaget LM Ericsson (publ)
InventorRichard Hellberg
Life of this patent
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Abstract
A composite amplifier includes a main power amplifier (10) and an auxiliary power amplifier (12), which are connected to a load (26) over a Doherty output network. An attenuator (34) is provided for activating the auxiliary power amplifier (12) before the main amplifier (10) is saturated. Preferably the input drive voltage to the auxiliary power amplifier (12) is increased along a smooth curve as the input signal amplitude to the composite amplifier increases.
Claims10
A composite amplifier including:
- a main amplifier and an auxiliary amplifier, which are connected to a load over a Doherty output network;
- and
- means for activating said auxiliary amplifier before said main amplifier is saturated by providing an auxiliary amplifier output current function that depends on the composite amplifier output voltage and has:
- (a) a non-zero auxiliary amplifier output current (i2) below the main amplifier saturation point;
- and
- (b) a lower slope for non-zero low auxiliary amplifier output currents than for high auxiliary amplifier output currents.
3 more elements
Dependencies are inferred from the claim text.