Patents by Inventor Cristian Grecu

Cristian Grecu has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 12388455
    Abstract: A piecewise linear current-mode digital-to-analog converter circuit approximates an exponential output current over a range of input codes by generating linearly varying currents with different slopes of different ranges of the input codes. The piecewise linear current-mode digital-to-analog converter circuit includes a current generator circuit that generates the output current based on a reference voltage and a feedback signal. A variable resistance circuit is used to generate the feedback signal using the output current. Respective values of the reference voltage and the variable resistance circuit vary as a function of the input code.
    Type: Grant
    Filed: June 21, 2023
    Date of Patent: August 12, 2025
    Assignee: Apple Inc.
    Inventors: Nicola Rasera, Cristian Grecu, Bogdan-Eugen Matei, Fabio Ongaro, Ming Sun
  • Patent number: 12273977
    Abstract: A high current, low dropout driver circuit is disclosed. The circuit includes a decoder configured to decode a plurality of control bits to generate a plurality of control signals, and a current source having a plurality of devices. The current source is configured to activate at least a subset of the plurality of devices using the control signals to provide a load current to a load circuit, such as a light-emitting diode (LED), using activated ones of the plurality of devices and a control voltage. A control circuit is configured to generate the control voltage based on the load current and a reference current.
    Type: Grant
    Filed: June 21, 2023
    Date of Patent: April 8, 2025
    Assignee: Apple Inc.
    Inventors: Cristian Grecu, Nicola Rasera, Bogdan-Eugen Matei, Fabio Ongaro
  • Publication number: 20240431001
    Abstract: A high current, low dropout driver circuit is disclosed. The circuit includes a decoder configured to decode a plurality of control bits to generate a plurality of control signals, and a current source having a plurality of devices. The current source is configured to activate at least a subset of the plurality of devices using the control signals to provide a load current to a load circuit, such as a light-emitting diode (LED), using activated ones of the plurality of devices and a control voltage. A control circuit is configured to generate the control voltage based on the load current and a reference current.
    Type: Application
    Filed: June 21, 2023
    Publication date: December 26, 2024
    Inventors: Cristian Grecu, Nicola Rasera, Bogdan-Eugen Matei, Fabio Ongaro
  • Publication number: 20240429931
    Abstract: A piecewise linear current-mode digital-to-analog converter circuit approximates an exponential output current over a range of input codes by generating linearly varying currents with different slopes of different ranges of the input codes. The piecewise linear current-mode digital-to-analog converter circuit includes a current generator circuit that generates the output current based on a reference voltage and a feedback signal. A variable resistance circuit is used to generate the feedback signal using the output current. Respective values of the reference voltage and the variable resistance circuit vary as a function of the input code.
    Type: Application
    Filed: June 21, 2023
    Publication date: December 26, 2024
    Inventors: Nicola Rasera, Cristian Grecu, Bogdan-Eugen Matei, Fabio Ongaro, Ming Sun
  • Patent number: 11594957
    Abstract: A dual-stage boost converter is disclosed. The boost converter includes a charge pump and a boost stage. The charge pump is coupled between an input voltage source and the boost stage. The charge pump is coupled to receive the input voltage and configured to generate an intermediate voltage that is greater than the input voltage received from the input voltage source. The boost stage includes an inductor coupled to receive the intermediate voltage and is configured to generate an output voltage that is greater than or equal to the intermediate voltage.
    Type: Grant
    Filed: March 16, 2021
    Date of Patent: February 28, 2023
    Assignee: Apple Inc.
    Inventors: Bogdan-Eugen Matei, Cristian Grecu, Fabio Ongaro, Giovanni Saccomanno, Siarhei Meliukh, Yesim Inam
  • Publication number: 20220302826
    Abstract: A dual-stage boost converter is disclosed. The boost converter includes a charge pump and a boost stage. The charge pump is coupled between an input voltage source and the boost stage. The charge pump is coupled to receive the input voltage and configured to generate an intermediate voltage that is greater than the input voltage received from the input voltage source. The boost stage includes an inductor coupled to receive the intermediate voltage and is configured to generate an output voltage that is greater than or equal to the intermediate voltage.
    Type: Application
    Filed: March 16, 2021
    Publication date: September 22, 2022
    Inventors: Bogdan-Eugen Matei, Cristian Grecu, Fabio Ongaro, Giovanni Saccomanno, Siarhei Meliukh, Yesim Inam
  • Patent number: 11166355
    Abstract: An LED driver circuit is disclosed. The LED driver circuit includes an amplifier having a first input coupled to receive a reference voltage and a second input coupled to receive a feedback voltage. The circuit further includes first and second transistors each having respective gate terminals coupled to an output of the first amplifier. In a first mode, a first switch alternately couples a source terminal of the first transistor to the second input of the amplifier (when the pulse is asserted) and a source terminal of the second transistor to the second input (when the pulse is de-asserted). A third transistor includes a gate terminal that is coupled to ground, by a second switch, when operating in the first mode. When operating in the second mode, the switch couples the third transistor to the output of the amplifier, while the pulse remains asserted.
    Type: Grant
    Filed: June 22, 2020
    Date of Patent: November 2, 2021
    Assignee: Apple Inc.
    Inventors: Cristian Grecu, Bogdan-Eugen Matei, Angelo Bassi, Andrei-Cosmin Gaidam, Alessandro Molari
  • Publication number: 20210153320
    Abstract: An LED driver circuit is disclosed. The LED driver circuit includes an amplifier having a first input coupled to receive a reference voltage and a second input coupled to receive a feedback voltage. The circuit further includes first and second transistors each having respective gate terminals coupled to an output of the first amplifier. In a first mode, a first switch alternately couples a source terminal of the first transistor to the second input of the amplifier (when the pulse is asserted) and a source terminal of the second transistor to the second input (when the pulse is de-asserted). A third transistor includes a gate terminal that is coupled to ground, by a second switch, when operating in the first mode. When operating in the second mode, the switch couples the third transistor to the output of the amplifier, while the pulse remains asserted.
    Type: Application
    Filed: June 22, 2020
    Publication date: May 20, 2021
    Inventors: Cristian Grecu, Bogdan-Eugen Matei, Angelo Bassi, Andrei-Cosmin Gaidam, Alessandro Molari
  • Patent number: 10694603
    Abstract: An LED driver circuit is disclosed. The LED driver circuit includes an amplifier having a first input coupled to receive a reference voltage and a second input coupled to receive a feedback voltage. The circuit further includes first and second transistors each having respective gate terminals coupled to an output of the first amplifier. In a first mode, a first switch alternately couples a source terminal of the first transistor to the second input of the amplifier (when the pulse is asserted) and a source terminal of the second transistor to the second input (when the pulse is de-asserted). A third transistor includes a gate terminal that is coupled to ground, by a second switch, when operating in the first mode. When operating in the second mode, the switch couples the third transistor to the output of the amplifier, while the pulse remains asserted.
    Type: Grant
    Filed: November 14, 2019
    Date of Patent: June 23, 2020
    Assignee: Apple Inc.
    Inventors: Cristian Grecu, Bogdan-Eugen Matei, Angelo Bassi, Andrei-Cosmin Gaidam, Alessandro Molari