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US 2006/0220590 A1Published application
Operational amplifier, and amplitude modulator and transmitter using the same
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsMitsuru Tanabe, Taiji Akizuki, Koichiro Tanaka, Takuo Hino
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Abstract
The operational amplifier outputs a signal for switching a switch circuit from a drive circuit according to signal amplitude information inputted from a signal source to thereby switch a plurality of supply voltages of a power amplification circuit arranged in an output portion. As a result of this, needed minimum DC power required for linear amplification for the voltage amplitude to be outputted can be provided to the power amplification circuit, allowing the operational amplifier to achieve an improvement in efficiency.
Claims17
An operational amplifier comprising:
- a differential amplifier for receiving a signal electric power;
- a power amplification circuit for amplifying an output voltage of said differential amplifier;
- and
- power control means for step-wisely switching at least either of a DC power supply voltage applied to said power amplification circuit and a direct current supplied to said power amplification circuit according to a voltage amplitude value of said signal electric power.
1 more element
Dependencies are inferred from the claim text.