Micrel Patent Grants

DMOS transistor with trench schottky diode

Granted: December 27, 2016
Patent Number: 9530880
A DMOS transistor integrates a trench Schottky diode into the body contact of the transistor where the body region surrounding the Schottky metal layer forms a guard ring for the Schottky diode.

Vertical differential resonator

Granted: November 8, 2016
Patent Number: 9490769
A micromechanical device includes a substrate, a micromechanical structure supported by the substrate and configured for overtone resonant vibration relative to the substrate, and a plurality of electrodes supported by the substrate and spaced from the micromechanical structure by respective gaps. The plurality of electrodes include multiple drive electrodes configured relative to the micromechanical structure to excite the overtone resonant vibration with a differential excitation…

Infusion rotary peristaltic pump

Granted: October 18, 2016
Patent Number: 9468715
An infusion pump comprises at least three operating layers. A first layer includes epicyclic gear means comprising a rotatable central gear, a stationary outer ring gear, and movable planet gears arranged between the central gear and the ring gear in movable engagement with the central and ring gears. A second layer includes roller bearing means comprising a stationary outer ring and a movable inner roller arrangement in movable arrangement with the outer ring and coupled with the…

High bandwidth PSRR power supply regulator

Granted: October 18, 2016
Patent Number: 9471076
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…

Buck DC-DC converter with fixed frequency

Granted: October 11, 2016
Patent Number: 9467043
A buck switching regulator implements a fixed frequency feedback control circuit including a voltage control loop and a frequency control loop to regulate the switching frequency of the buck switching regulator to a fixed or nearly fixed frequency. The voltage control loop, implementing ripple mode control, is configured to control the power switches in response to the switching regulator output voltage or a signal related to the switching regulator output voltage. The frequency control…

Switching regulator using adaptive slope compensation with DC correction

Granted: October 11, 2016
Patent Number: 9467051
A switching regulator using current mode control and adaptive slope compensation includes a DC correction circuit to introduce a DC correction signal to cancel the DC offset error generated by the slope compensation signal. In some embodiments, the DC correction signal is a function of the input voltage and the output voltage and is applied in response to the slope compensation signal being applied. In one embodiment, the DC correction signal is a linear function of the input voltage and…

Hysteretic buck DC-DC converter

Granted: September 27, 2016
Patent Number: 9455626
A buck switching regulator includes a feedback control circuit using a four-input comparator to regulate the output voltage to a substantially constant level with reduced voltage offset and with fast transient response. In some embodiments, the buck switching regulator uses the four-input comparator to compare a first feedback signal without ripple and a second feedback signal with injected ripple components to a reference level. The four-input comparator generates an output signal to…

Temperature compensated resonator with a pair of spaced apart internal dielectric layers

Granted: August 30, 2016
Patent Number: 9431993
A device includes a substrate, an electrode supported by the substrate, an anchor supported by the substrate, and a composite structure supported by the anchor, disposed adjacent the electrode, and configured for resonant vibration. The composite structure includes an external layer and an internal dielectric region covered by the external layer.

Last gasp hold-up circuit using adaptive constant on time control

Granted: May 10, 2016
Patent Number: 9335772
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 to drive the power switches in the boost mode…

Boost regulator incorporating peak inductor current modulation

Granted: April 26, 2016
Patent Number: 9325243
A boost switching regulator incorporates a peak inductor current modulation circuit to modulate the peak inductor current as a function of the load current, the input voltage, the regulated output voltage, and a fixed current value. In this manner, the switching frequency of the boost regulator can be maintained above a given value or within a given frequency range over a wide range of load conditions and also over input voltage variations and output voltage settings.

Optimal ripple injection for a boost regulator

Granted: April 5, 2016
Patent Number: 9306454
A boost switching regulator incorporates a ripple injection circuit to generate a voltage ripple signal for feedback control that mimics the actual ripple signal of the regulated output voltage. In this manner, the ripple injection circuit achieves optimal ripple injection for stable and enhanced feedback control. In one embodiment, the injected ripple signal is generated from a current injection signal that mimics the difference between the inductor current that flows through the…

ESD protection for MEMS resonator devices

Granted: February 23, 2016
Patent Number: 9266722
Disclosed herein are MEMS resonator device designs and fabrication techniques that provide protection against electrostatic charge imbalances. In one aspect, a MEMS resonator device includes a substrate, an electrode including a first microstructure supported by the substrate, a resonant element including a second microstructure spaced from the first microstructure by a gap for resonant displacement of the second microstructure within the gap during operation, and a disabled shunt…

PLL frequency synthesizer with multi-curve VCO implementing closed loop curve searching

Granted: January 19, 2016
Patent Number: 9240796
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…

Current sharing method for COT buck converter

Granted: December 15, 2015
Patent Number: 9214866
A power system for providing an output current at a regulated system output voltage includes a first power stage and a second power stage, each being a constant on-time (COT) controlled power converter. The first and second power stages generate respective first and second regulated output voltage having reduced or very small output ripple at a common output voltage node. The first and second power stages each includes a ripple injection circuit to inject a ripple signal to the feedback…

Buck DC-DC converter with accuracy enhancement

Granted: December 1, 2015
Patent Number: 9201438
A buck switching regulator includes a feedback control circuit including a first gain circuit generating a first feedback signal indicative of the regulated output voltage; a ripple generation circuit generating a ripple signal that is injected to the first feedback signal; and a comparator receiving a first reference signal and the first feedback signal to generate a comparator output signal. The switching regulator further includes an offset compensation circuit including a second gain…

Time-to-digital converter

Granted: November 17, 2015
Patent Number: 9188961
A time-to-digital converter (TDC) incorporates a resistor-stabilized delay line, a sampling circuit and a processing circuit. The resistor-stabilized delay line operates to limit the variation in delay values for the delay elements in the delay line due to fabrication process variations. In some embodiments, the resistor-stabilized delay line limits the delay variation of each delay element to a fraction of the delay.

Planar vertical DMOS transistor with a conductive spacer structure as gate

Granted: November 10, 2015
Patent Number: 9184278
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…

Planar vertical DMOS transistor with reduced gate charge

Granted: November 3, 2015
Patent Number: 9178054
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…

Signal level detect circuit with reduced loss-of-signal assertion delay

Granted: October 20, 2015
Patent Number: 9166702
A signal level detect circuit configured to assess an input signal with varying amplitude signal levels and to generate an indicator signal includes an input circuit configured to receive the input signal and to process the input signal, the input circuit including a first node on which the input signal is sampled; a comparator configured to compare the processed input signal to a signal level threshold and generate a comparator output signal; and an active discharge circuit configured…

Battery charger voltage control method for instant boot-up

Granted: October 6, 2015
Patent Number: 9153987
A battery charger voltage control method dynamically adjusts the system voltage generated by a battery charger circuit based on the operating conditions to ensure that sufficient power is supplied to power up the circuitry of the electronic device when the battery charger circuit is connected to a current-limited power source and the battery of the electronic device is deeply depleted or is missing. In embodiments of the present invention, the battery charger voltage control method sets…