# US 2018/0323749 A1 · Communication apparatus with isolation of the receive chain > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0323749 A1 - Document ID: US20180323749A1 - Status: Published application - Kind: A1 - Application number: 15/945,384 - Filed: 2018-04-04 - Published: 2018-11-08 - Earliest claimed: 2017-05-05 - Assignees: ST Microelectronics SA - Applicants: ST Microelectronics SA - Inventors: Laurent Chabert - Web page: https://patentgrep.com/patent/US20180323749A1 ## CPC - H03F 1/223: {with MOSFET's} - H03F 1/26: Modifications of amplifiers to reduce influence of noise generated by amplifying elements - H03F 1/523: {for amplifiers using field-effect devices (H03F1/526 takes precedence)} - H03F 1/565: {using inductive elements} - H03F 3/195: in integrated circuits - H03F 3/72: Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal - H04B 1/16: Circuits - H04B 1/44: Transmit/receive switching - H04B 1/48: in circuits for connecting transmitter and receiver to a common transmission path, e.g. by energy of transmitter {(H04B1/46 takes precedence)} - H03F 3/20: Power amplifiers, e.g. Class B amplifiers, Class C amplifiers (H03F3/26 - H03F3/30 take precedence) - H03F 2200/222: A circuit being added at the input of an amplifier to adapt the input impedance of the amplifier - H03F 2200/294: the amplifier being a low noise amplifier [LNA] - H03F 2200/372: Noise reduction and elimination in amplifier - H03F: AMPLIFIERS - H04B: TRANSMISSION ## Abstract A communication apparatus includes an antenna and a receive chain. The receive chain includes a switching transistor, and amplification transistor and a discharge transistor. The amplification transistor has a control terminal coupled to a current path terminal of the switching transistor. The discharge transistor has a current path coupled between the control terminal of the amplification transistor and a ground terminal. The discharge circuit is configured to discharge an intrinsic capacitance of the switching circuit when the switching transistor is in an off state. ## Claims ### Claim 1 A communication apparatus comprising: an antenna; and a receive chain comprising an amplifier device and a controllable switching circuit coupled between an input of the amplifier device and the antenna; wherein the controllable switching circuit has an intrinsic capacitance; wherein the controllable switching circuit has an off state and an on state; wherein the amplifier device comprises an inductive element and a discharge circuit, the inductive element coupled between the switching circuit and the discharge circuit; and wherein the discharge circuit of the amplifier device is coupled to the switching circuit to discharge the intrinsic capacitance of the switching circuit in the off state. ### Claim 2 (depends on 1) The communication apparatus according to claim 1, wherein the amplifier device further comprises an amplification transistor that is coupled to an input of the amplifier device by the inductive element, wherein the discharge circuit is connected between the inductive element and the amplification transistor. ### Claim 3 (depends on 1) The communication apparatus according to claim 1, wherein the discharge circuit comprises a controllable discharge transistor. ### Claim 4 (depends on 3) The communication apparatus according to claim 3, wherein the discharge circuit comprises a matrix of transistors. ### Claim 5 (depends on 1) The communication apparatus according to claim 1, wherein the discharge circuit comprises a matrix of discharge transistors controllable by a common control signal. ### Claim 6 (depends on 1) The communication apparatus according to claim 1, wherein the amplifier device comprises an amplification transistor. ### Claim 7 (depends on 6) The communication apparatus according to claim 6, wherein the amplifier device further comprises a ground terminal, a control electrode of the amplification transistor being connected to an input of the amplifier device and the discharge circuit being connected between the control electrode of the amplification transistor and the ground terminal. ### Claim 8 (depends on 6) The communication apparatus according to claim 6, wherein the amplifier device further comprises a ground terminal, the discharge circuit being connected between a source of the amplification transistor and the ground terminal. ### Claim 9 (depends on 1) The communication apparatus according to claim 1, further comprising a transmit chain that comprises a power amplifier coupled to the antenna by a second controllable switching circuit having an off state and an on state. ### Claim 10 A communication apparatus comprising a receive chain, the receive chain comprising: an antenna node; an impedance-matching inductive element; a switching transistor having a current path coupled between the antenna node and a first terminal of the impedance-matching inductive element; a discharge transistor coupled between a second terminal of the impedance-matching inductive element and a ground terminal; an amplification transistor coupled to the second terminal of the impedance-matching inductive element, the amplification transistor having a current path between a first transistor terminal and a second transistor terminal; a resistive element coupled between the first transistor terminal of the amplification transistor and a reference supply terminal; and a degeneration inductive element coupled between the second transistor terminal of the amplification transistor and the ground terminal. ### Claim 11 (depends on 10) The communication apparatus of claim 10, wherein the amplification transistor has a control terminal coupled to the second terminal of the impedance-matching inductive element. ### Claim 12 (depends on 11) The communication apparatus of claim 11, further comprising a further transistor having a current path coupled between the second transistor terminal of the amplification transistor and the resistive element, the further transistor also having a control terminal coupled to a bias voltage node. ### Claim 13 (depends on 10) The communication apparatus of claim 10, wherein the amplification transistor has a control terminal coupled to a bias voltage node. ### Claim 14 (depends on 13) The communication apparatus of claim 13, further comprising a further transistor having a current path coupled between the second transistor terminal of the amplification transistor and the resistive element, the further transistor also having a control terminal coupled to a second bias voltage node. ### Claim 15 (depends on 10) The communication apparatus of claim 10, wherein the discharge transistor comprises a plurality of transistors coupled between a second terminal of the impedance-matching inductive element and a ground terminal. ### Claim 16 (depends on 15) The communication apparatus of claim 15, wherein the plurality of transistors comprises a matrix of transistors. ### Claim 17 (depends on 10) The communication apparatus of claim 10, further comprising an antenna coupled to the antenna node. ### Claim 18 (depends on 17) The communication apparatus of claim 17, further comprising: a baseband circuit with an input coupled to a second terminal of the impedance-matching inductive element, the discharge transistor having a control terminal coupled to an output of the baseband circuit; and a transmit chain coupled between the antenna and the baseband circuit. ### Claim 19 (depends on 10) The communication apparatus of claim 10, wherein the switching transistor has an off state and an on state and wherein the discharge transistor is configured to discharge an intrinsic capacitance of the switching transistor in the off state. ### Claim 20 A receive chain of a communication device, the receive chain comprising: a switching transistor an amplification transistor having a control terminal coupled to a current path terminal of the switching transistor; and a discharge transistor having a current path coupled between the control terminal of the amplification transistor and a ground terminal, wherein the discharge transistor is configured to discharge an intrinsic capacitance of the switching transistor when the switching transistor is in an off state. ### Claim 21 (depends on 20) The receive chain of claim 20, further comprising a resistive element coupled between a first current path terminal of the amplification transistor and a reference supply terminal; an impedance-matching inductive element coupled between a second current path terminal of the switching transistor and an antenna node; and a degeneration inductive element coupled between a second current path terminal of the amplification transistor and the ground terminal. ### Claim 22 (depends on 20) The receive chain of claim 20, wherein the discharge transistor comprises a matrix of transistors that each have a current path coupled between the control terminal of the amplification transistor and the ground terminal, wherein control terminals of each transistor of the matrix are coupled together.