Drain sharing split LNA
AssigneepSemi Corporation
InventorsMiles Sanner, Emre Ayranci
Life of this patent
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Abstract
A receiver front end having low noise amplifiers (LNAs) is disclosed herein. A cascode having a “common source” configured input FET and a “common gate” configured output FET can be turned on or off using the gate of the output FET. A first switch is provided that allows a connection to be either established or broken between the source terminal of the input FET of each LNA. A drain switch is provided between the drain terminals of input FETs to place the input FETs in parallel. This increases the gm of the input stage of the amplifier, thus improving the noise figure of the amplifier.
Claims36
An amplifier including:
- (a) a plurality of low noise amplifiers (LNA), each including an input transistor and an output transistor;
- (b) at least two control input terminals, each coupled to an output transistor of a corresponding one of the LNAs;
- and
- (c) at least one drain switch having a first terminal coupled to the source of a first of the output transistors and to the drain of a first of the input transistors and a second terminal coupled to the source of a second of the output transistors and to the drain of a second of the input transistors, the at least one drain switch connecting drain terminals of the first and second input transistors of at least two of the LNAs during a first mode of operation and disconnecting the drain terminals during at least a second mode of operation.
A method for amplifying a signal in more than one amplifier including:
- (a) coupling the signal to be amplified to the input of at least a first and second LNA, each LNA having an input transistor and an output transistor, each transistor having a first terminal, a second terminal and a third terminal;
- (b) coupling the second terminal of the output transistor of the first LNA to the third terminal of the input transistor of the first LNA;
- (c) coupling the second terminal of the output transistor of the second LNA to the third terminal of the input transistor of the second LNA;
- (d) turning on the output transistors of the first and second LNAs during a first mode;
- (e) opening a switch between the third terminal of the input transistor of the first LNA and the third terminal of the input transistor of the second LNA during the first mode;
- (f) turning off one of the output transistors during a second mode;
- and
- (g) closing the switch between the third terminal of the first and second input transistors in the second mode.
Dependencies are inferred from the claim text.