Patents Assigned to Micrel, Inc.
  • Patent number: 9128125
    Abstract: A current sense resistor integrated with an integrated circuit die where the integrated circuit die is housed in a flip-chip semiconductor package includes a metal layer formed over a passivation layer of the integrated circuit die where the metal layer having an array of metal pillars extending therefrom. The metal pillars are electrically connected to a first leadframe portion and a second leadframe portion of the semiconductor package where the first leadframe portion and the second leadframe portion are electrically isolated from each other and physically separated by a separation of a first distance. The current sense resistor is formed in a portion of the metal layer spanning the separation between the first and second leadframe portions, the first and second leadframe portions forming terminals of the current sense resistor.
    Type: Grant
    Filed: June 14, 2012
    Date of Patent: September 8, 2015
    Assignee: Micrel, Inc.
    Inventor: Cameron Jackson
  • Patent number: 9094197
    Abstract: An energy efficient Ethernet physical layer (PHY) device including an EEE control module configured to generate a control signal to transition the PHY device into a low power consumption mode based an operating condition, and a pause frame generator module responsive to the control signals to generate a pause frame. The pause frame generator module is configured to send the pause frame to a media access control (MAC) device to reduce an incoming flow of data packets from the MAC device to the PHY device for a pause time duration. In operation, the pause frame generator module generates the pause frame including a pause time indicating the length of time for the PHY device to be in the low power consumption mode. The value of the pause time for each pause frame is determined adaptively based on the type of data traffic to be transmitted from the PHY device.
    Type: Grant
    Filed: December 16, 2014
    Date of Patent: July 28, 2015
    Assignee: Micrel, Inc.
    Inventors: Wei-Chieh Chang, Wei-Chi Lo, Charng-Show Li, Menping Chang
  • Patent number: 9093899
    Abstract: A control circuit in a PFM/PWM boost switching regulator includes a timer based PFM exit control circuit configured to receive a first control signal for controlling a main power switch, a zero-cross signal indicative of an inductor current having reached zero current value, and a timer reference signal indicative of a timer threshold duration. The timer based PFM exit control circuit assesses an idle time of the inductor current based on the first control signal and the zero-cross signal. The timer based PFM exit control circuit asserts the PFM exit signal in response to the idle time decreasing below a level being equal to or less than the timer threshold duration, and the boost switching regulator transitions out of the PFM mode and into the PWM mode in response to the PFM exit signal being asserted.
    Type: Grant
    Filed: September 30, 2013
    Date of Patent: July 28, 2015
    Assignee: Micrel, Inc.
    Inventors: Vinit Jayaraj, Jayant Rao
  • Publication number: 20150162431
    Abstract: A planar vertical DMOS transistor includes a dielectric separation structure formed under the conductive gate and over the bulk of the semiconductor layer outside of the channel region of the transistor. The planar vertical DMOS transistor with a conductive gate formed over the dielectric structure reduces the parasitic gate-to-bulk or gate-to-drain overlap capacitance by increasing the separation between the conductive gate and the bulk of the semiconductor layer. Meanwhile, the desired distance between the body regions formed on opposing sides of the conductive gate is maintained.
    Type: Application
    Filed: December 9, 2013
    Publication date: June 11, 2015
    Applicant: Micrel, Inc.
    Inventor: David Raymond Zinn
  • Publication number: 20150162430
    Abstract: A planar vertical DMOS transistor uses a conductive spacer structure formed on the sides of a dielectric structure as the gate of the transistor. The planar vertical DMOS transistor with a conductive spacer gate structure reduces the parasitic gate-to-bulk or gate-to-drain overlap capacitance by eliminating the conductive gate material that is formed above the bulk of the semiconductor layer. Meanwhile, the desired distance between the body regions formed on opposing sides of the conductive spacer gate structure is maintained.
    Type: Application
    Filed: December 9, 2013
    Publication date: June 11, 2015
    Applicant: Micrel, Inc
    Inventor: David Raymond Zinn
  • Patent number: 9048848
    Abstract: A phase-locked loop circuit using a multi-curve voltage-controlled oscillator (VCO) having a set of operating curves, each operating curve corresponding to a different frequency range over a control voltage range. The phase-locked loop circuit includes a phase and frequency detector driving a charge pump and a digital control circuit configured to perform a closed loop curve search operation to select one of the operating curves in the multi-curve VCO and to perform a curve tracking operation using the selected operating curve, the selected operating curve being used by the VCO to generate an output signal with an output frequency being equal or close to a target frequency of the phase-locked loop. In one embodiment, the digital control circuit increases the charge pump current above a nominal current value during the closed loop curve search operation and set the charge pump current to the nominal current during the curve tracking operation.
    Type: Grant
    Filed: September 23, 2014
    Date of Patent: June 2, 2015
    Assignee: Micrel, Inc.
    Inventors: Juinn-Yan Chen, Wei-Kang Cheng
  • Patent number: 9030241
    Abstract: A phase-locked loop circuit using a multi-curve voltage-controlled oscillator (VCO) having a set of operating curves, each operating curve corresponding to a different frequency range over a control voltage range. The phase-locked loop circuit includes a digital control circuit configured to generate a curve select signal using a closed loop curve search operation to select one of the operating curves in the multi-curve VCO, the selected operating curve being used by the VCO to generate an output signal with an output frequency being equal or close to a target frequency of the phase-locked loop. In one embodiment, the digital control circuit implements a binary jump method and an operating curve is selected when the operating curve has an output frequency meeting the target frequency with the control voltage being within a first voltage range being a narrowed and centered voltage range within the control voltage range.
    Type: Grant
    Filed: April 30, 2013
    Date of Patent: May 12, 2015
    Assignee: Micrel, Inc.
    Inventors: Juinn-Yan Chen, Wei-Kang Cheng
  • Patent number: 9025629
    Abstract: A laser driver circuit having a differential circuit and an output circuit includes a control circuit receiving a regulated supply voltage that also supplies the differential circuit as an input signal. The control circuit generates a feedback voltage across a first resistor to cause a first current to flow in the first resistor having a current value equal or proportional to the modulation current value. The laser driver circuit includes an operational amplifier receiving the feedback voltage and a reference voltage indicative of a desired modulation current value and to generate the regulated supply voltage. The control circuit and the operational amplifier form a feedback control loop to adjust the regulated supply voltage to regulate the feedback voltage to be equal to the reference voltage, thereby regulating the modulation current value to the desired modulation current value.
    Type: Grant
    Filed: December 3, 2012
    Date of Patent: May 5, 2015
    Assignee: Micrel, Inc.
    Inventors: Bernd Neumann, Dieter Kuehnel, Maik Pohland
  • Patent number: 9013165
    Abstract: A multi-mode pulse width modulation (PWM) controller for a buck switching regulator includes a multi-mode PWM control circuit where the PWM control circuit is configured to operate in one of multiple control schemes selectable by a mode select signal. In one embodiment, the multi-mode PWM control circuit incorporates a peak current mode control scheme, a voltage mode control scheme, and a valley current mode control scheme. In another embodiment, the multi-mode PWM control circuit further incorporates a constant ON-time control scheme.
    Type: Grant
    Filed: March 7, 2013
    Date of Patent: April 21, 2015
    Assignee: Micrel, Inc.
    Inventors: Nitin Kalje, Mansour Izadinia
  • Publication number: 20150091544
    Abstract: A control circuit in a PFM/PWM boost switching regulator includes a timer based PFM exit control circuit configured to receive a first control signal for controlling a main power switch, a zero-cross signal indicative of an inductor current having reached zero current value, and a timer reference signal indicative of a timer threshold duration. The timer based PFM exit control circuit assesses an idle time of the inductor current based on the first control signal and the zero-cross signal where the idle time is the time period when the inductor current has the zero current value. The timer based PFM exit control circuit asserts the PFM exit signal in response to the idle time being equal to or less than the timer threshold duration, and the boost switching regulator transitions out of the PFM mode and into the PWM mode in response to the PFM exit signal being asserted.
    Type: Application
    Filed: September 30, 2013
    Publication date: April 2, 2015
    Applicant: Micrel, Inc.
    Inventors: Vinit Jayaraj, Jayant Rao
  • Patent number: 8957655
    Abstract: A hold-up circuit coupled to a first node to receive an input voltage and to provide a hold-up voltage includes an inductor, a constant on-time buck-boost control circuit configured to drive a high-side power switch and a low-side power switch to operate in a buck mode and a boost mode of operation, and an energy storage capacitor. When the input voltage is greater than a predetermined threshold, the buck-boost control circuit is configured in the boost mode to drive the low-side power switch with constant on-time pulses and to charge the energy storage capacitor under non-synchronous operation. When the input voltage is less than a predetermined threshold, the buck-boost control circuit is configured in the buck mode to drive the high-side power switch with constant on-time pulses and to drive the low-side power switch under synchronous operation to provide the hold-up voltage to the first node.
    Type: Grant
    Filed: March 16, 2012
    Date of Patent: February 17, 2015
    Assignee: Micrel, Inc.
    Inventor: Martin F. Galinski, III
  • Patent number: 8942144
    Abstract: An energy efficient Ethernet physical layer (PHY) device including an EEE control module configured to generate a control signal to transition the PHY device into a low power consumption mode based an operating condition, and a pause frame generator module responsive to the control signals to generate a pause frame. The pause frame generator module is configured to send the pause frame to a media access control (MAC) device to reduce an incoming flow of data packets from the MAC device to the PHY device for a pause time duration. In operation, the pause frame generator module generates the pause frame including a pause time indicating the length of time for the PHY device to be in the low power consumption mode. The value of the pause time for each pause frame is determined adaptively based on the amount of data traffic to be transmitted from the PHY device.
    Type: Grant
    Filed: May 12, 2011
    Date of Patent: January 27, 2015
    Assignee: Micrel, Inc.
    Inventors: Wei-Chieh Chang, Wei-Chi Lo, Charng-Show Li, Menping Chang
  • Patent number: 8922187
    Abstract: A buck switching regulator includes a feedback control circuit including a balanced feedback network including first and second gain circuits configured to generate first and second feedback signals, respectively, indicative of the regulated output voltage; a ripple generation circuit configured to inject a first ripple signal to the first gain circuit and a second ripple signal to the second gain circuit; an operational transconductance amplifier (OTA) configured to receive the second feedback signal and a reference signal and to generate an output signal being coupled to a node in the feedback control circuit; and a comparator configured to receive the first feedback signal and a comparator reference signal and to generate a comparator output signal. The output signal of the OTA is applied to the feedback control circuit to cancel a voltage offset in the regulated output voltage due to the injected ripple signal to the first gain circuit.
    Type: Grant
    Filed: March 11, 2013
    Date of Patent: December 30, 2014
    Assignee: Micrel, Inc.
    Inventor: Leland Swanson
  • Patent number: 8922271
    Abstract: A voltage-current conversion circuit for automatic test equipment (ATE) or a tester converts a low voltage, low current output from a power supply of the tester to a high voltage and/or high current output to be coupled to a device under test (DUT) while maintaining the sense capability of the tester power supply. In some embodiments, the voltage-current conversion circuit is implemented as a current only conversion circuit.
    Type: Grant
    Filed: July 29, 2013
    Date of Patent: December 30, 2014
    Assignee: Micrel, Inc.
    Inventors: Rajesh Moothedath, Douglas Falco
  • Patent number: 8890499
    Abstract: A buck switching regulator includes a feedback control circuit including a feedback network including first and second gain circuits configured to generate first and second feedback signals, respectively, indicative of the regulated output voltage; a ripple generation circuit configured to inject a ripple signal to the first gain circuit; an operational transconductance amplifier (OTA) configured to receive the second feedback signal and a reference signal and to generate an output signal being coupled to the first gain circuit to adjust the first feedback signal; and a comparator configured to receive the first feedback signal and the reference signal and to generate a comparator output signal. The output signal of the OTA is applied to the first feedback signal to cancel a voltage offset in the regulated output voltage due to the injected ripple signal to the first gain circuit.
    Type: Grant
    Filed: March 11, 2013
    Date of Patent: November 18, 2014
    Assignee: Micrel, Inc.
    Inventors: Leland Swanson, Dashun Xue, William MacLean
  • Patent number: 8889518
    Abstract: The present invention provides a laterally diffused metal oxide semiconductor (LDMOS) transistor and a method for fabricating it. The LDMOS transistor includes an n-type epitaxial layer formed on a p-type substrate, and an asymmetric conductive spacer which acts as its gate. The LDMOS transistor also includes a source and a drain region on either side of the asymmetric conductive spacer, and a channel region formed by ion-implantation on the asymmetric conductive spacer. The height of the asymmetric conductive spacer increases from the source region to the drain region. The channel region is essentially completely under the asymmetric conductive spacer and has smaller length than that of the channel region of the prior art LDMOS transistors. The LDMOS transistor of the present invention also includes a field oxide layer surrounding the active region of the transistor, and a thin dielectric layer isolating the asymmetric conductive spacer from the n-type epitaxial layer.
    Type: Grant
    Filed: July 30, 2013
    Date of Patent: November 18, 2014
    Assignee: Micrel, Inc.
    Inventors: Martin Alter, Paul McKay Moore
  • Publication number: 20140327416
    Abstract: A voltage regulator includes a power device formed by an NMOS transistor having a drain terminal coupled to an input voltage, a source terminal providing an output voltage and a gate terminal receiving a gate drive signal; and an integrated AC/DC control loop configured to access the output voltage and to generate the gate drive signal based on a value of the output voltage in relation to a first reference voltage and a second reference voltage. The AC control portion generates a gate drive control signal which is AC coupled to the gate terminal of the power device as an AC component of the gate drive signal. The DC control portion controls a DC voltage level of the gate drive signal. The AC control portion is powered by the input voltage while the DC control portion is powered by a high supply voltage greater than the input voltage.
    Type: Application
    Filed: May 5, 2014
    Publication date: November 6, 2014
    Applicant: Micrel, Inc.
    Inventors: Rudolf Gerardus van Ettinger, Paul Wilson
  • Patent number: 8878501
    Abstract: A multi-phase power block for a switching regulator includes a phase control circuit, N power cells and a current sharing control circuit. The phase control circuit is configured to receive a single phase PWM clock signal and generate N clock signals in N phases. Each of the N power cells includes a pair of power switches, gate drivers, a control circuit receiving one of the N clock signals and generating gate drive signals for the gate drivers, and an inductor. The current sharing control circuit is configured to assess the inductor current at the inductor of the N power cells and to generate duty cycle control signals for the N power cells. The duty cycle control signals are applied to the control circuits to adjust the duty cycle of one or more clock signals supplied to the power cells to balance a current loading among the N power cells.
    Type: Grant
    Filed: March 29, 2012
    Date of Patent: November 4, 2014
    Assignee: Micrel, Inc.
    Inventors: Nitin Kalje, Mansour Izadinia
  • Patent number: 8878387
    Abstract: An integrated circuit supplied by a rail-to-rail power supply voltage includes a multi-level stack voltage generator configured to partition the rail-to-rail power supply voltage into one or more reduced supply voltages each having a voltage value between positive and negative power supply voltages of the rail-to-rail power supply. The reduced supply voltages and the positive and negative power supply voltages being configured in series to form a stack of circuit layers. The integrated circuit further includes a core circuit including core circuit units coupled in a circuit layer or coupled between two or more circuit layers. Each core circuit unit is coupled to at least one of the reduced supply voltages. The core circuit units are coupled in the stack of circuit layers to form a serial connection of core circuit units between the positive power supply voltage and the negative power supply voltage.
    Type: Grant
    Filed: May 16, 2013
    Date of Patent: November 4, 2014
    Assignee: Micrel, Inc.
    Inventors: Thomas S. Wong, Gang Luo
  • Patent number: 8878287
    Abstract: The present invention provides an FET which includes an epitaxial layer and first and second body regions formed over the epitaxial layer. Further, the FET includes a first trench formed in the epitaxial layer between the first and the second body regions. The FET also includes a conductive layer formed on the sidewall of the first trench. The conductive layer acts as gate of the FET. The FET also includes a second trench formed at the bottom of the first trench, a first dielectric layer formed over the conductive layer and on the sidewall of the second trench, and a second dielectric layer formed on the first dielectric layer. Further, the FET includes a conductive layer, which acts as drain, deposited in the first and the second trenches. The FET also includes first and a second source regions formed in the first and second body regions, respectively.
    Type: Grant
    Filed: April 12, 2012
    Date of Patent: November 4, 2014
    Assignee: Micrel, Inc.
    Inventor: Paul McKay Moore