Back to results
US 2006/0132237 A1Published application
Linear-in-dB variable gain amplifiers with an adaptive bias current
AssigneeTheta Microelectronics, Inc.
InventorGerasimos Zochios
Life of this patent
Estimating the term…
Abstract
Linear-in-dB current-steering VGAs with an adaptive bias current operable so that as the gain of the amplifier decreases, the DC current consumption also decreases. The modified VGA circuits result in power consumption savings, which are of particular value in wireless (battery powered) applications.
Claims14
A linear-in-dB variable gain amplifier comprising:
- a linear-in-dB amplifier core;
- and,
- a first exponential current source coupled to bias the linear-in-dB amplifier core with a current exponentially responsive to a first control signal.
A linear-in-dB variable gain amplifier circuit comprising:
- first, second and third transistors each having an emitter, a base and a collector;
- said first and second transistors having their respective emitters coupled to each other and further having their respective bases coupled to each other, the bases of the first and second transistors being further connected to the collector of said first transistor to form a current mirror;
- a first controllable exponential current source connected between a power supply and the collector of said first transistor;
- a load connected between said power supply and said collector of said second transistor;
- a bias transistor having its collector connected to said power supply, its emitter coupled to the emitter of said first transistor, and its base being coupled to a bias voltage;
- a transconductance amplifier capable of converting an input signal to a proportionate current, the output of said transconductance amplifier being coupled to the emitter of said first transistor;
- and,
- a second controllable exponential current source connected to said transconductance amplifier.
5 more elements
A method for controlling the gain in an amplifier, comprising:
- providing a linear-in-dB variable gain amplifier operative on a bias;
- providing the bias current from a controllable exponential current source;
- causing the bias current of said linear-in-dB variable gain amplifier to decrease when the gain decreases.
Dependencies are inferred from the claim text.