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US 5,703,524 AGranted
Piece-wise linear approximation of a dB linear programmable gain amplifier
AssigneeExar Corporation
InventorXiaole Chen
Life of this patent
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Abstract
A programmable gain amplifier which can be realized using CMOS transistors. The amplifier provides a plurality of linear gain segments, with each of the gain segments having a different gain. A particular combination of the gain segments are selected using a digital control input to give an approximation of a linear dB output. By appropriately choosing the segments and how they combine, an approximation that is accurate to the least significant bit of a digital system can be provided.
Claims15
A programmable gain amplifier comprising:
- a plurality of linear gain segments, each of said linear gain segments having a different gain;
- a multiple bit digital control input;
- and
- selection logic, coupled to said multiple bit digital control input, configured to selectively enable desired ones of said linear gain segments.
1 more element
A programmable gain amplifier comprising:
- a constant current source;
- a plurality of CMOS gain transistors of different sizes;
- a first plurality of switching transistors connected between said constant current source and said CMOS gain transistors;
- a fractional current generating circuit coupled to said constant current source;
- and
- a second plurality of switching transistors connected between said fractional current generating circuit and said plurality of CMOS gain transistors.
3 more elements
Dependencies are inferred from the claim text.