# US 7,612,616 B2 · Low-noise amplifier > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,612,616 B2 - Document ID: US7612616B2 - Status: Granted - Kind: B2 - Application number: 12/137,641 - Filed: 2008-06-12 - Published: 2009-07-30 - Granted: 2009-11-03 - Earliest claimed: 2008-01-25 - Assignees: National Taiwan University - Inventors: Ping-Yuan Deng; Jean-Fu Kiang - Web page: https://patentgrep.com/patent/US7612616B2 ## CPC - H03F 3/193: with field-effect devices (H03F3/195 takes precedence) - H03F 1/0205: {in transistor amplifiers} - H03F 1/565: {using inductive elements} - H03F 2200/108: A coil being added in the drain circuit of a FET amplifier stage, e.g. for noise reducing purposes - H03F 2200/222: A circuit being added at the input of an amplifier to adapt the input impedance of the amplifier - H03F 2200/255: Amplifier input adaptation especially for transmission line coupling purposes, e.g. impedance adaptation - H03F 2200/294: the amplifier being a low noise amplifier [LNA] - H03F 2200/318: A matching circuit being used as coupling element between two amplifying stages - H03F 2200/387: A circuit being added at the output of an amplifier to adapt the output impedance of the amplifier - H03F 2200/408: the output amplifying stage of an amplifier comprising three power stages - H03F 2200/451: the amplifier being a radio frequency amplifier - H03F 2200/492: A coil being added in the source circuit of a transistor amplifier stage as degenerating element - H03F: AMPLIFIERS ## Abstract A low-noise amplifier is provided according to the present invention. The low-noise amplifier includes a first amplifier stage, a second amplifier stage, a third amplifier stage, an input matching network, inter-stage matching networks, and an output matching network. The impedance of the input matching network and the input impedance of the first amplifier stage are conjugate matched, thereby decreasing system power consumption and noise factor. The system gain is enhanced by cascading three stages of amplifiers. ## Claims ### Claim 1 A low-noise amplifier comprising: an input matching network; a first amplifier stage having an input end and an output end, the input end being connected to the input matching network, the first amplifier stage having an input impedance in conjugate matching relation with the impedance of the input matching network; a second amplifier stage having an input end and an output end; a first inter-stage matching network connected to the output end of the first amplifier stage and the input end of the second amplifier stage, to form a conjugate matching relation between the output impedance of the first amplifier stage and the input impedance of the second amplifier stage; a third amplifier stage having an input end and an output end; a second inter-stage matching network connected to the output end of the second amplifier stage and the input end of the third amplifier stage, to form a conjugate matching relation between the output impedance of the second amplifier stage and the input impedance of the third amplifier stage; and an output matching network connected to the output end of the third amplifier stage. ### Claim 2 (depends on 1) The low-noise amplifier of claim 1, wherein the first amplifier stage is a common-source single-transistor amplifier comprising: a first transistor having a gate connected to the input matching network, the gate being the input end of the first amplifier stage; and an inductor connected between the source of the first transistor and the ground. ### Claim 3 (depends on 2) The low-noise amplifier of claim 2, wherein the input matching network comprises: a capacitor connected between a radio-frequency signal input end of the low-noise amplifier and the gate of the first transistor; and an inductor connected between the gate of the first transistor and a power supply. ### Claim 4 (depends on 3) The low-noise amplifier of claim 3, wherein the power supply is further connected to a bypass capacitor. ### Claim 5 (depends on 2) The low-noise amplifier of claim 2, wherein the first inter-stage matching network comprises: an inductor connected to the drain of the first transistor and a power supply; and a capacitor connected to the drain of the first transistor and the input end of the second amplifier stage. ### Claim 6 (depends on 5) The low-noise amplifier of claim 5, wherein the power supply is further connected to a bypass capacitor. ### Claim 7 (depends on 1) The low-noise amplifier of claim 1, wherein the second amplifier stage is a common-source single-transistor amplifier comprising: a second transistor having the gate connected to the first inter-stage matching network, the gate of the second transistor being the input end of the second amplifier stage; an inductor connected between the source of the second transistor and the ground; and a resistor connected between the gate of the second transistor and a power supply. ### Claim 8 (depends on 7) The low-noise amplifier of claim 7, wherein the second inter-stage matching network comprises: an inductor connected between the drain of the second transistor and a power supply; and a capacitor connected to the drain of the second transistor and the input end of the third amplifier stage. ### Claim 9 (depends on 8) The low-noise amplifier of claim 8, wherein the power supply is further connected to a bypass capacitor. ### Claim 10 (depends on 1) The low-noise amplifier of claim 1, wherein the third amplifier stage is a common-source single-transistor amplifier comprising: a third transistor having the gate connected to the second inter-stage matching network, the gate of the third transistor being the input end of the third amplifier stage; an inductor connected between the source of the third transistor and the ground; and a resistor connected between the gate of the third transistor and a power supply. ### Claim 11 (depends on 10) The low-noise amplifier of claim 10, wherein the output matching network comprises: an inductor connected between the drain of the third transistor and a power supply; and a capacitor connected to the drain of the third transistor and the radio-frequency signal output end of the low-noise amplifier. ### Claim 12 (depends on 11) The low-noise amplifier of claim 11, wherein the power supply is further connected to a bypass capacitor.