Feedback topologies for amplifier gain reduction
AssigneepSemi Corporation
InventorsParvez Daruwalla, Rong Jiang, Khushali Shah
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Abstract
Feedback methods and devices to reduce gain in RF amplifiers, more in particular LNAs, are disclosed. The described methods are based on providing feedback paths from the drain terminal of one of the LNA cascode transistors to the source terminal of the LNA input transistor, or from the gate terminal of the input transistor to the source terminal of the LNA input transistor. The disclosed methods can be combined with one another or with existing feedback methods to provide further flexibility and improved tradeoffs when designing LNAs for applications having different requirements.
Claims23
A radio frequency (RF) amplifier comprising:
- one or more transistors being serially connected, wherein a first transistor of the one or more transistors is configured to receive a first input signal from a first input terminal;
- a first feedback path including a first programmable resistor coupling a drain terminal of a transistor of the one or more transistors to a source terminal of the first transistor of the one or more of transistors, and
- a second feedback path including a second programmable resistor coupling a gate terminal of the first transistor to the source terminal of the first transistor.
A radio frequency (RF) amplifier comprising:
- one or more transistors being serially connected, wherein a first transistor of the one or more transistors is configured to receive a first input signal from a first input terminal;
- and
- a first feedback path including a first programmable resistor coupling a gate terminal of the first transistor to a source terminal of the first transistor.
A method of reducing gain in a radio frequency (RF) amplifier, the method comprising:
- providing one or more transistors being serially connected;
- applying an input signal to a gate terminal of a first transistor of the one or more transistors;
- providing a first feedback path including a first programmable resistor, the first feedback path coupling a drain terminal of a transistor of the one or more transistors to the gate terminal of the first transistor;
- providing a second feedback path including a second programmable resistor, the second feedback path coupling the drain terminal of the transistor to a source terminal of the first transistor;
- providing a third feedback path including a third programmable resistor, the third feedback path coupling the gate-terminal of the first transistor of the one or more transistors to the source-terminal of the first transistor of the one or more transistors;
- selectively switching in and out one or more of the first, second, and the third feedback paths based on a set requirement, and
- further adjusting the gain by varying one or more of the first, second, and the third programmable resistors.
Dependencies are inferred from the claim text.