Patents Assigned to Micrel, Incorporated
  • Publication number: 20070241731
    Abstract: A low-dropout voltage (LDO) regulator that creates a zero in the open loop gain using a relatively small-sized current control element to divert part of the supplied load current through a “zero” resistor before adding it to the output load. The main part of the output load is passed through a relatively large second current control element. A control signal generated by an error amplifier (e.g., an op-amp) is used to control the small current control element, but is passed through a boost zero compensating resistor before being applied to the large current control element. The voltage signal developed across the “zero” resistor mimics the magnitude and phase of a zero in the loop. This voltage signal is added to the loop gain by, for instance, using a bypass capacitor, and the resulting feedback signal is supplied to the error amplifier.
    Type: Application
    Filed: June 18, 2007
    Publication date: October 18, 2007
    Applicant: Micrel, Incorporated
    Inventor: Roel van Ettinger
  • Publication number: 20070235816
    Abstract: A BiCMOS integrated circuit (IC) includes a floating gate-type non-volatile memory (NVM) device that uses the polycrystalline silicon gate of a CMOS FET and the P-base and N-emitter diffusions of a bipolar transistor to provide an isolated P-type body and N-type source/drain diffusions. The P-body diffusion of the NVM device is isolated from a P-substrate by an N-well, thus facilitating the use of reduced positive and negative voltage levels to produce the onset of Fowler-Nordheim tunneling without the need for a triple-well structure. The polysilicon gate structure is formed on a suitable gate oxide over the P-body. The source/drain diffusions, which like the N-emitter diffusions of the bipolar transistor have no LDD, produce a reduced field drop across the gate oxide to allow Fowler-Nordheim tunneling from the source side.
    Type: Application
    Filed: April 5, 2006
    Publication date: October 11, 2007
    Applicant: Micrel, Incorporated
    Inventor: Paul Moore
  • Publication number: 20070216384
    Abstract: An OTA driving an MOS device needs to turn it off quickly to minimize overshoot during a heavy to light load state. The drains of the MOS device can be used to accelerate turning off the MOS device. A first drain is connected to the gate of the MOS device. A second drain is connected to a base of a bipolar device. The emitter of the bipolar device is connected to the MOS device gate. Notably, this bipolar device is active during the heavy to light load state. Therefore, any current provided by the second drain is then multiplied by the beta of the bipolar device. The increased current generated on the emitter of the bipolar transistor and provided to the gate of the MOS device can advantageously accelerate the turnoff of that MOS device. The first drain can provide minimal additional current during the heavy to light load state.
    Type: Application
    Filed: March 20, 2006
    Publication date: September 20, 2007
    Applicant: Micrel, Incorporated
    Inventor: Michael Mottola
  • Publication number: 20070216479
    Abstract: A method of reducing the settling time of an amplifier includes providing a pre-set voltage on a high gain node of the amplifier when the amplifier is disabled. This pre-set voltage can be slightly less than the regulated voltage. In this manner, when the amplifier is enabled, the high gain node can quickly reach this regulated voltage. The pre-set voltage can be applied to the high gain node by operating a switch, e.g. if the amplifier is enabled (disabled), then the switch is open (closed). A startup circuit can generate the pre-set voltage. This startup circuit can include a startup current source and a transistor connected in series between VDD and VSS. The switch can be connected to the gate and drain of the transistor. Notably, the transistor can be the same type of device as the MOS device driven by the high gain node in the amplifier.
    Type: Application
    Filed: March 20, 2006
    Publication date: September 20, 2007
    Applicant: Micrel, Incorporated
    Inventor: Michael Mottola
  • Patent number: 7272744
    Abstract: A transmitting device communicates a multi-level clock signal to a receiving device. Changes in the clock level may indicate the start or stop of a transmitting message or delineate fields in the transmitted message. The number of clock pulses received at a particular voltage may indicate further information about the message.
    Type: Grant
    Filed: May 19, 2004
    Date of Patent: September 18, 2007
    Assignee: Micrel, Incorporated
    Inventor: George Claseman
  • Patent number: 7248026
    Abstract: A voltage regulator includes a voltage divider connected between a soft-start pin and the voltage regulator's error amplifier. The voltage divider has the same divider ratio as that of the voltage regulator's feedback voltage divider, which is used to divide the regulated output voltage fed back to the error amplifier. To facilitate soft-start operations, an external, user-supplied capacitor is connected to the soft-start pin. To facilitate voltage tracking operations, a predetermined master supply voltage is applied to the soft-start pin.
    Type: Grant
    Filed: November 28, 2005
    Date of Patent: July 24, 2007
    Assignee: Micrel, Incorporated
    Inventor: David Wayne Ritter
  • Publication number: 20070139025
    Abstract: A PFM-type voltage regulator circuit converts an unregulated input voltage into a regulated output voltage using a first transistor controlled by a pulse control circuit and a second transistor controlled by a linear regulator circuit. The linear regulator circuit controls the second transistor when the regulated output voltage falls to a predetermined minimum target voltage level, thereby maintaining the regulated output voltage at the minimum target voltage level. The pulse control circuit detects the current passing through the second transistor, and in response generates a pulse signal having a predetermined duration that fully turns on the first transistor. The voltage through the first transistor is converted to an increasing inductor current that refreshes the regulated output voltage to a maximum target voltage level. When the pulse signal ends, the regulated output voltage again begins to fall toward the predetermined minimum target voltage level, and the cycle is repeated.
    Type: Application
    Filed: December 21, 2005
    Publication date: June 21, 2007
    Applicant: Micrel, Incorporated
    Inventors: Charles Vinn, Raymond Zinn
  • Patent number: 7230408
    Abstract: A PFM-type voltage regulator circuit converts an unregulated input voltage into a regulated output voltage using a first transistor controlled by a pulse control circuit and a second transistor controlled by a linear regulator circuit. The linear regulator circuit controls the second transistor when the regulated output voltage falls to a predetermined minimum target voltage level, thereby maintaining the regulated output voltage at the minimum target voltage level. The pulse control circuit detects the current passing through the second transistor, and in response generates a pulse signal having a predetermined duration that fully turns on the first transistor. The voltage through the first transistor is converted to an increasing inductor current that refreshes the regulated output voltage to a maximum target voltage level. When the pulse signal ends, the regulated output voltage again begins to fall toward the predetermined minimum target voltage level, and the cycle is repeated.
    Type: Grant
    Filed: December 21, 2005
    Date of Patent: June 12, 2007
    Assignee: Micrel, Incorporated
    Inventors: Charles L. Vinn, Raymond D. Zinn
  • Patent number: 7227388
    Abstract: A comparator circuit having improved operational characteristics. A predetermined voltage drop device is provided, such as an exemplary embodiment Schottky diode, having an anode connected to circuit power supply voltage and an output stage of the comparator and a cathode connected to an input stage of the comparator. The predetermined voltage drop device effects a lowering of the power supply voltage for the output stage bias between said power supply voltage and said common voltage. This reduces the required swing of the output stage drivers during a comparator input signal transition and reduces propagation delay of said comparator.
    Type: Grant
    Filed: May 9, 2005
    Date of Patent: June 5, 2007
    Assignee: Micrel, Incorporated
    Inventors: Matthew Weng, Charles Vinn
  • Publication number: 20070120544
    Abstract: A voltage regulator includes a voltage divider connected between a soft-start pin and the voltage regulator's error amplifier. The voltage divider has the same divider ratio as that of the voltage regulator's feedback voltage divider, which is used to divide the regulated output voltage fed back to the error amplifier. To facilitate soft-start operations, an external, user-supplied capacitor is connected to the soft-start pin. To facilitate voltage tracking operations, a predetermined master supply voltage is applied to the soft-start pin.
    Type: Application
    Filed: November 28, 2005
    Publication date: May 31, 2007
    Applicant: Micrel, Incorporated
    Inventor: David Ritter
  • Patent number: 7224727
    Abstract: The present invention provides an apparatus and method for encoding and/or decoding signals. The encoding apparatus includes a variable impedance being coupled with an encoder. The variable impedance establishes a select voltage at the encoder. The encoder is further coupled with an input signal, wherein the encoder generates a modulated output as dictated by the select voltage. The decoding apparatus includes an integrator, a comparator and at least a first variable impedance. The integrator couples with the comparator, and is configured to receive an encoded signal and to generate an average DC voltage, such that the comparator receives the average DC voltage. The first variable impedance coupled with the comparator, and dictates a first limit such that the comparator receives the first limit. The comparator is configured to generate a decoded signal if the average DC voltage is at least equal to the first limit.
    Type: Grant
    Filed: September 28, 2001
    Date of Patent: May 29, 2007
    Assignee: Micrel, Incorporated
    Inventor: Raymond D. Zinn
  • Patent number: 7211893
    Abstract: Wafer-level chip-scale packaging technology is used for improving performance or reducing size of integrated circuits by using metallization of pad-to-bump-out beams as part of the integrated circuit structure. Chip-scale packaging under bump metal is routed to increase the thickness of top metal of the integrated circuit, increasing current carrying capability and reducing resistance. An exemplary embodiment for a power MOSFET array integrated structure is described. Another exemplary embodiment illustrated the use of chip-scale processes for interconnecting discrete integrated circuits.
    Type: Grant
    Filed: November 3, 2004
    Date of Patent: May 1, 2007
    Assignee: Micrel, Incorporated
    Inventors: Martin Alter, Robert Rumsey
  • Patent number: 7203213
    Abstract: An accelerator circuit is incorporated in a laser diode system for accelerating the turn-on operation of the laser diode independent of the control loop bandwidth of the laser diode system. The accelerator circuit provides a boost current to a compensation capacitor upon laser turn-on which compensation capacitor operates to establish the control loop bandwidth of the laser diode system. The boost current enables the control loop to increase the bias current to the laser diode quickly. When the laser diode reaches the desired operating point, the boost current is terminated and the control loop of the laser diode system resumes normal control of the bias current. In one embodiment, the accelerator circuit includes a timer circuit controlling a current source to implement open loop turn-on control. In another embodiment, the accelerator circuit includes a comparator circuit working in conjunction with an one-shot logic circuit for providing close loop control.
    Type: Grant
    Filed: January 15, 2004
    Date of Patent: April 10, 2007
    Assignee: Micrel, Incorporated
    Inventors: Douglas P. Anderson, Peter Chambers, Joseph J. Judkins, III, William Andrew Burkland
  • Publication number: 20070052403
    Abstract: An analog soft-start circuit for a switching regulator (e.g., a buck converter) including an analog ramp circuit and an open-loop analog voltage clamp circuit. The voltage ramp circuit utilizes a two-stage current divider circuit to generate a very low, stable current signal, and an integrator circuit including a relatively small, integral capacitor to generate the ramp voltage signal in response to the very low current signal. The analog voltage clamp circuit clamps the regulated output signal to the ramp voltage until the ramp voltage signal increases to a predetermined voltage level, thereby causing the regulated output voltage to exhibit the desired soft-start characteristics. The analog clamp circuit includes a current mirror circuit that generates a clamp current that pulls down the error amplifier output stage via a clamping element (e.g., a diode) until the ramp voltage signal reaches a predetermined level.
    Type: Application
    Filed: August 24, 2005
    Publication date: March 8, 2007
    Applicant: Micrel, Incorporated
    Inventor: Ioan Stoichita
  • Publication number: 20070046345
    Abstract: A delay-locked loop (DLL) employs an in-loop duty cycle corrector (DCC) to provide accurate multiphase clock generation with 50% duty cycle. Each delay cell can advantageously provide both delay and duty cycle correction functionality. In one embodiment, delay correction can precede duty cycle correction. The bandwidths of the DCC and the DLL can differ by a factor of a decade to achieve fast and stable operation.
    Type: Application
    Filed: August 24, 2005
    Publication date: March 1, 2007
    Applicant: Micrel, Incorporated
    Inventors: Gwo-Chung Tai, Kin Hui
  • Patent number: 7177325
    Abstract: The invention includes a protocol, systems and methods for operating, administering, and maintaining (OAM) physical links in a network that carries packet switched data. A network control point implementing the protocol assigns addresses to all ports of the network, discovers network topology and capabilities, and initializes remote parameters through OAM frames sent to the ports. The OAM protocol maintains all physical transmission links through the communication of OAM frames with information concerning link errors and the status of ports and boxes. The OAM frame has a preamble that is an inverse of a preamble of a data frame, allowing decoupling of the OAM and data services. The OAM frames are initiated and terminated at the physical layer of the network. Ports of the network may include ASIC integrated circuits that create, transmit, receive, and process the OAM frames at the physical layer of the ports.
    Type: Grant
    Filed: July 25, 2002
    Date of Patent: February 13, 2007
    Assignee: Micrel, Incorporated
    Inventor: George R. Claseman
  • Publication number: 20070030074
    Abstract: Control loops in a voltage regulator can be stabilized using minimal silicon area. A current limit signal, generated by a current limit control loop in the voltage regulator, can be divided to minimize a zero provided in a compensation set associated with a voltage control loop, thereby stabilizing both loops. The compensation set can include a resistor (the zero) and a capacitor (a pole) connected in series between output and input terminals of an amplifier. Dividing the current limit signal can include injecting a first portion of the current limit signal on a first side of the resistor and injecting a second portion of the current limit signal on a second side of the resistor. The ratio of the first and second portions can be based on a gain of the amplifier, thereby minimizing an effect of the resistor.
    Type: Application
    Filed: August 5, 2005
    Publication date: February 8, 2007
    Applicant: Micrel, Incorporated
    Inventor: David W. Ritter
  • Patent number: 7169018
    Abstract: A tool and method for assessing whether a disk carrier, and especially a carrier for holding semiconductor disks, is properly dimensioned. The tool has a body that includes a socket in which a portion of the disk carrier will seat fully if the disk carrier is properly dimensioned. Alignment structures may be provided in the socket to align with features of the carrier to assist in determining whether the disk carrier is properly dimensioned. The socket may include two spaced apart cavities that correspond with end portions of walls of the disk carrier.
    Type: Grant
    Filed: May 4, 2005
    Date of Patent: January 30, 2007
    Assignee: Micrel, Incorporated
    Inventor: Michael John Kundracik
  • Patent number: 7170732
    Abstract: A surge current delay time period is added to a current limit delay time period in order to permit a longer time for a possibly temporary larger-than-steady-state electrical current, such as for a start-up power requirement. A system is described for permitting a legitimate surge current by distinguishing true over-current fault conditions from temporary surges in terms of high current duration time.
    Type: Grant
    Filed: August 10, 2004
    Date of Patent: January 30, 2007
    Assignee: Micrel Incorporated
    Inventors: David Andersen, Thruston Awalt
  • Patent number: 7166826
    Abstract: An automatic power control system provides a control signal that regulates the output power of at least one laser diode. Coarse adjustment of the control signal is provided by a first means, preferably a digital variable resistor, while fine adjustment and compensation is provided by a second means, preferably by a digital-to-analog converter that receives an input signal proportional to a sensed control system parameter. The control system includes an operational amplifier having a first input coupled to sense output power, and a second input coupled to a DAC to provide finer resolution control. Memory can store system parameter or system parameter variations that can be coupled to the DAC and/or variable resistor to enhance system stability over ambient variations.
    Type: Grant
    Filed: November 13, 2002
    Date of Patent: January 23, 2007
    Assignees: Micrel, Incorporated, Stratos Lightware, Inc.
    Inventors: David Kunst, Steven Martinez, Robert James Lewandowski, Peter Chambers, Joseph James Judkins, III, Luis Torres, Tom Lindsay