# US 11,444,545 B2 · Multiple stage gate drive for cascode current sensing > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,444,545 B2 - Document ID: US11444545B2 - Status: Granted - Kind: B2 - Application number: 17/146,521 - Filed: 2021-01-12 - Published: 2021-07-08 - Granted: 2022-09-13 - Earliest claimed: 2017-06-12 - Assignees: Power Integrations, Inc. - Applicants: Power Integrations, Inc. - Inventors: Rajko Duvnjak - Web page: https://patentgrep.com/patent/US11444545B2 ## CPC - H02M 7/1626: {with automatic control of the output voltage or current} - H02H 1/0007: {concerning the detecting means (in general G01R or other subclasses of G01; reed switches H01H71/2445)} - H02H 7/1227: {responsive to abnormalities in the output circuit, e.g. short circuit} - H02M 1/12: Arrangements for reducing harmonics from AC input or output - H02M 1/32: Means for protecting converters other than automatic disconnection - H02M 1/44: Circuits or arrangements for compensating for electromagnetic interference in converters or inverters - H02M 3/33507: {with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence)} - H02M 7/125: {Avoiding or suppressing excessive transient voltages or currents} - H03K 17/0822: {in field-effect transistor switches} - H03K 17/102: {in field-effect transistor switches} - H03K 17/163: {Soft switching} - H03K 17/6871: {the output circuit comprising more than one controlled field-effect transistor} - G01R 19/0092: {Measuring current only} - H02M 1/0009: {Devices or circuits for detecting current in a converter} - H03K 2017/6875: {using self-conductive, depletion FETs} - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices 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) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A power converter comprising an energy transfer element is coupled between an input of the power converter and an output of the power converter. A cascode circuit generates a first sense signal and a second sense signal. A controller controls the switching of the cascode circuit to transfer energy from the input of the power converter to the output of the power converter. The controller comprising a current sense circuit generates a current limit signal and an overcurrent signal in response to the first sense signal and the second sense signal. A control circuit generates a control signal in response to the current limit signal and the overcurrent signal. A drive circuit comprising a first stage gate drive circuit generates a drive signal in response to the control signal to reduce EMI, and a second stage of gate drive circuit to enable accurate current sensing of the cascode circuit. ## Claims ### Claim 1 A power converter, comprising: an energy transfer element coupled between an input of the power converter and an output of the power converter; a cascode circuit coupled to the energy transfer element, the cascode circuit including a normally-on GaN switch and a control switch, the control switch configured to generate a first sense signal and a second sense signal; a current sensor configured to generate a current limit signal and an overcurrent signal in response to the first sense signal and the second sense signal; a control circuit configured to generate a control signal in response to the current limit signal and the overcurrent signal; and a drive circuit configured to generate a drive signal in response to the control signal, wherein a first stage of the drive circuit is configured to provide the drive signal to reduce EMI, and a second stage of the drive circuit is configured to provide the drive signal to enable accurate current sensing of the cascode circuit. ### Claim 2 (depends on 1) The power converter of claim 1, wherein the first sense signal is generated by a drain of a first sense finger of the control switch and a first current source. ### Claim 3 (depends on 1) The power converter of claim 1, wherein the second sense signal is generated by a drain terminal of a second sense finger of the control switch coupled to a second current source. ### Claim 4 (depends on 1) The power converter of claim 1, the current sensor further coupled to receive a source signal generated by a source terminal of the normally-on GaN switch. ### Claim 5 (depends on 4) The power converter of claim 4, the current sensor comprising: a first comparator configured to generate the current limit signal when the source signal is greater than the first sense signal; and a second comparator configured to generate the overcurrent signal when the source signal is greater than the second sense signal. ### Claim 6 (depends on 4) The power converter of claim 4, the drive circuit comprising: a first transistor configured to generate the drive signal of the first stage of the multiple stage gate drive circuit in response to the control signal; a delay circuit configured to generate a delay signal in response to the control signal; and a second transistor configured to generate the drive signal of the second stage of the multiple stage gate drive circuit in response to the delay signal. ### Claim 7 A controller configured for use in a power converter, comprising: a current sensor configured to generate a current limit signal in response to a first sense signal representative of a switch current of a control switch, the current sensor further configured to generate an overcurrent signal in response to a second sense signal for regulating an output voltage of the power converter; a control circuit configured to generate a control signal in response to the current limit signal and the overcurrent signal; and a multiple stage gate drive circuit configured to generate a drive signal for a cascode circuit in response to the control signal, wherein a first stage of the multiple stage gate drive circuit is configured to provide the drive signal to reduce EMI, and wherein a second stage of the multiple stage gate drive circuit is configured to provide the drive signal to enable current sensing of the cascode circuit. ### Claim 8 (depends on 7) The controller of claim 7, the current sense circuit comprising: a first comparator configured to generate the current limit signal in response to a source signal of the cascode circuit being greater than the first sense signal; and a second comparator configured to generate the overcurrent signal in response to the source signal being greater than the second sense signal. ### Claim 9 (depends on 7) The power converter of claim 7, the drive circuit comprising: a first transistor configured to generate the drive signal of the first stage of the multiple stage gate drive circuit in response to the control signal; a delay circuit configured to generate a delay signal in response to the control signal; and a second transistor configured to generate the drive signal of the second stage of the multiple stage gate drive circuit in response to the delay signal. ### Claim 10 A controller configured for use in a power converter, comprising: a current sensor coupled to receive a first sense signal representative of a switch current of a control switch of a cascode circuit and a second sense signal for regulating an output voltage of the power converter of the control switch; and a drive circuit configured to generate a drive signal for the cascode circuit by use of a multiple stage gate drive circuit, wherein the drive signal provided by a first stage of the multiple stage gate drive circuit is configured to reduce EMI, and wherein the drive signal provided by a second stage of the multiple stage gate drive circuit is configured to enable current sensing of the cascode circuit. ### Claim 11 (depends on 10) The controller of claim 10, wherein a resistance of the first sense signal and the second sense signal is at a nominal value in response to the second stage of the multiple stage gate drive circuit. ### Claim 12 (depends on 10) The controller of claim 10, wherein the current sensor is configured to generate a current limit signal in response to the first sense signal, the current sense circuit further configured to generate an overcurrent signal in response to the second sense signal. ### Claim 13 (depends on 12) The controller of claim 12, further comprising a control circuit configured to generate a control signal in response to the current limit signal and the overcurrent signal. ### Claim 14 (depends on 13) The controller of claim 13, wherein the drive circuit is configured to generate the drive signal in response to the control signal.