# US 11,309,888 B2 · Reverse current switch > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,309,888 B2 - Document ID: US11309888B2 - Status: Granted - Kind: B2 - Application number: 16/686,097 - Filed: 2019-11-16 - Published: 2020-03-12 - Granted: 2022-04-19 - Earliest claimed: 2018-08-31 - Assignees: Shenzhen Goodix Technology Co., Ltd. - Applicants: Shenzhen Goodix Technology Co., Ltd. - Inventors: Mengwen Zhang - Web page: https://patentgrep.com/patent/US11309888B2 ## CPC - H03K 17/6872: {using complementary field-effect transistors} - A61B 5/02444: {Details of sensor (A61B5/02427 takes precedence)} - H03K 3/02337: {Bistables with hysteresis, e.g. Schmitt trigger (non-regenerative amplitude discriminators G01R19/165)} - H04R 1/1041: {Mechanical or electronic switches, or control elements (switches in general H01H)} - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) ## Abstract Provided is a reverse current switch. The reverse current switch includes: a comparison unit including a first input end, a second input end, and a first output end; and a switch resistance unit, where a first end of the switch resistance unit is connected to the first input end, a second end of the switch resistance unit is connected to the second input end, and a third end of the switch resistance unit is connected to the output end of the comparison unit, and the switch resistance unit is controlled by a voltage of the first output end. This reverse current switch has a simple structure and can implement working under low voltage conditions. ## Claims ### Claim 1 A reverse current switch, comprising: a comparison unit comprising a first input end, a second input end, and a first output end; and a switch resistance unit, wherein a first end of the switch resistance unit is connected to the first input end, a second end of the switch resistance unit is connected to the second input end, and a third end of the switch resistance unit is connected to the first output end, wherein the switch resistance unit is controlled by a voltage of the first output end; when a voltage of the first input end is greater than a voltage of the second input end, the voltage of the first output end controls the switch resistance unit to be in an on state; or when a voltage of the first input end is less than a voltage of the second input end, the voltage of the first output end controls the switch resistance unit to be in an off state; wherein the reverse current switch further comprises: a voltage controlled unit comprising a voltage controlled resistance unit and a voltage controlled voltage generation unit, wherein the voltage controlled resistance unit and the switch resistance unit are connected in series between the first input end and the second input end, the voltage controlled voltage generation unit is connected in parallel with the comparison unit, and voltage controlled voltage generation unit comprises a second output end, wherein when a difference between the voltage of the first input end and the voltage of the second input end increases, a voltage of the second output end controls a resistance value of the voltage controlled resistance unit to decrease. ### Claim 2 (depends on 1) The reverse current switch according to claim 1, wherein when the difference between the voltage of the first input end and the voltage of the second input end decreases, the voltage of the second output end controls the resistance value of the voltage controlled resistance unit to increase. ### Claim 3 (depends on 1) The reverse current switch according to claim 1, wherein the comparison unit comprises: a first metal-oxide-semiconductor (MOS) transistor, a second MOS transistor, a third MOS transistor, and a fourth MOS transistor, wherein a gate of the first MOS transistor is connected to a gate of the second MOS transistor, a gate of the third MOS transistor is connected to a gate of the fourth MOS transistor and a source of the third MOS transistor is connected to a source of the fourth MOS transistor, a drain of the first MOS transistor is connected to a drain of the third MOS transistor, a drain of the second MOS transistor and a drain of the fourth MOS transistor are respectively connected to the first output end, a source of the first MOS transistor is connected to the first input end, and a source of the second MOS transistor is connected to the second input end. ### Claim 4 (depends on 3) The reverse current switch according to claim 3, wherein the first MOS transistor and the second MOS transistor are PMOS transistors, the third MOS transistor and the fourth MOS transistor are NMOS transistors, the gate of the third MOS transistor and the gate of the fourth MOS transistor are respectively connected to a bias unit, and the source of the first MOS transistor is connected to the drain of the first MOS transistor. ### Claim 5 (depends on 4) The reverse current switch according to claim 4, wherein the voltage controlled resistance unit and the switch resistance unit are connected in series between the first input end and the source of the second MOS transistor; the voltage controlled voltage generation unit comprises a fifth MOS transistor that is a PMOS transistor and a first resistor, a drain of the fifth MOS transistor and one end of the first resistor are respectively connected to the second output end, a source of the fifth MOS transistor is connected to the second input end, a gate of the fifth MOS transistor is connected to the gate of the first MOS transistor, and the other end of the first resistor is connected to the source of the third MOS transistor; and the voltage controlled resistance unit is controlled by the voltage of the second output end. ### Claim 6 (depends on 3) The reverse current switch according to claim 3, wherein the first MOS transistor and the second MOS transistor are PMOS transistors, the third MOS transistor and the fourth MOS transistor are NMOS transistors, the gate of the first MOS transistor and the gate of the second MOS transistor are respectively connected to a bias unit, and the source of the third MOS transistor is connected to the drain of the third MOS transistor. ### Claim 7 (depends on 6) The reverse current switch according to claim 6, wherein the voltage controlled resistance unit and the switch resistance unit are connected in series between the first input end and the source of the second MOS transistor; the voltage controlled voltage generation unit comprises a fifth MOS transistor that is an NMOS transistor and a first resistor, a drain of the fifth MOS transistor and one end of the first resistor are respectively connected to the second output end, the other end of the first resistor is connected to the second input end, a gate of the fifth MOS transistor is connected to the gate of the third MOS transistor, and a source of the fifth MOS transistor is connected to the source of the third MOS transistor; and the voltage controlled resistance unit is controlled by the voltage of the second output end. ### Claim 8 (depends on 3) The reverse current switch according to claim 3, further comprising: a hysteresis generation unit, wherein when the voltage of the first input end is greater than the voltage of the second input end, the hysteresis generation unit increases a current of the fourth MOS transistor and/or decreases a current of the second MOS transistor; or when the voltage of the first input end is less than the voltage of the second input end, the hysteresis generation unit decreases a current of the fourth MOS transistor and/or increases a current of the second MOS transistor. ### Claim 9 (depends on 1) The reverse current switch according to claim 1, further comprising: an offset correction unit, wherein when the voltage of the first input end is equal to the voltage of the second input end, the offset correction unit performs offset correction on the reverse current switch. ### Claim 10 (depends on 1) The reverse current switch according to claim 1, wherein the switch resistance unit comprises a sixth MOS transistor and a second resistor in series, and a gate of the sixth MOS transistor is controlled by the voltage of the first output end. ### Claim 11 (depends on 1) The reverse current switch according to claim 1, wherein the voltage controlled resistance unit comprises a seventh MOS transistor and a third resistor in parallel, and a gate of the seventh MOS transistor is controlled by the voltage of the second output end. ### Claim 12 (depends on 1) The reverse current switch according to claim 1, wherein the first input end is connected to a power supply circuit, and the second input end is connected to a load circuit, wherein when the voltage of the first input end is greater than the voltage of the second input end, the power supply circuit charges a storage capacitor between the load circuit and the power supply circuit. ### Claim 13 (depends on 12) The reverse current switch according to claim 12, wherein the power supply circuit is a wire-controlled earphone, and the load circuit is a heart rate sensor. ### Claim 14 (depends on 1) The reverse current switch according to claim 1, wherein the first input end is connected to a power supply circuit, and the second input end is connected to a load circuit, when the voltage of the first input end is less than the voltage of the second input end, a storage capacitor is discharged to the load circuit. ### Claim 15 (depends on 14) The reverse current switch according to claim 14, wherein the power supply circuit is a wire-controlled earphone, and the load circuit is a heart rate sensor. ### Claim 16 A reverse current switch, comprising: a comparison unit comprising a first input end, a second input end, and a first output end; and a switch resistance unit, wherein a first end of the switch resistance unit is connected to the first input end, a second end of the switch resistance unit is connected to the second input end, and a third end of the switch resistance unit is connected to the first output end, wherein the switch resistance unit is controlled by a voltage of the first output end; when a voltage of the first input end is greater than a voltage of the second input end, the voltage of the first output end controls the switch resistance unit to be in an on state; or when a voltage of the first input end is less than a voltage of the second input end, the voltage of the first output end controls the switch resistance unit to be in an off state; wherein the reverse current switch further comprises: a voltage controlled unit comprising a voltage controlled resistance unit and a voltage controlled voltage generation unit, wherein the voltage controlled resistance unit and the switch resistance unit are connected in series between the first input end and the second input end, the voltage controlled voltage generation unit is connected in parallel with the comparison unit, and voltage controlled voltage generation unit comprises a second output end, when a difference between the voltage of the first input end and the voltage of the second input end decreases, a voltage of the second output end controls a resistance value of the voltage controlled resistance unit to increase. ### Claim 17 A reverse current switch, comprising: a comparison unit comprising a first input end, a second input end, and a first output end; and a switch resistance unit, wherein a first end of the switch resistance unit is connected to the first input end, a second end of the switch resistance unit is connected to the second input end, and a third end of the switch resistance unit is connected to the first output end, wherein the switch resistance unit is controlled by a voltage of the first output end: when a voltage of the first input end is greater than a voltage of the second input end, the voltage of the first output end controls the switch resistance unit to be in an on state; or when a voltage of the first input end is less than a voltage of the second input end, the voltage of the first output end controls the switch resistance unit to be in an off state; wherein the comparison unit comprises: a first metal-oxide-semiconductor (MOS) transistor, a second MOS transistor, a third MOS transistor, and a fourth MOS transistor, wherein a gate of the first MOS transistor is connected to a gate of the second MOS transistor, a gate of the third MOS transistor is connected to a gate of the fourth MOS transistor and a source of the third MOS transistor is connected to a source of the fourth MOS transistor, a drain of the first MOS transistor is connected to a drain of the third MOS transistor, a drain of the second MOS transistor and a drain of the fourth MOS transistor are respectively connected to the first output end, a source of the first MOS transistor is connected to the first input end, and a source of the second MOS transistor is connected to the second input end.