Efficient parallel-stage power amplifier

In a cellular communication system in which a plurality of users use radiotelephones to communicate information signals between one another via at least one cell site using code division multiple access (CDMA) spread spectrum communication signals, a radiotelephone transmit amplifier circuit disposed within said radiotelephone for providing an amplified CDMA signal in response to an input CDMA signal, said transmit amplifier circuit comprising:

• a plurality of amplifier stages coupled in parallel for amplifying said input CDMA signal, each of said plurality of amplifier stages having an amplifier stage input and an amplifier stage output;
• an input network, coupled to each of said amplifier stage inputs of said plurality of amplifier stages, for providing said input CDMA signal to a selected at least one of said plurality of amplifier stages;
• an output network, coupled to each of said amplifier stage outputs of said plurality of amplifier stages, for providing said amplified CDMA signal at an output network output node;
• a control circuit, coupled to said input network and said output network, for selecting said at least one of said plurality of amplifier stages in response to a power level of said amplified CDMA signal;
• and
• an amplifier circuit wherein said input signal comprises a sequence of code symbols, said control circuit for identifying transitions between said code symbols and enabling said input network to provide said input signal to a different selected at least one of said plurality of amplifier stages only at said transitions between said code symbols.