Micrel, Incorporated

Apple Inc.

Freescale Semiconductor,inc.

Dashun Xue

William MacLean

Michael Couleur

Fabio Ongaro

Leland Swanson

Jay B Fletcher

Ruopeng Wang

Yesim Inam

Jiandong Jiang

A power converter circuit that includes a switch node coupled to a regulated power supply node via an inductor may, during a discharge cycle, sink current from the regulated power supply node. A control circuit may generate the rising and falling ramp signals using voltage levels of an input power supply node and the regulated power supply node. The control circuit may also determine a duration of the discharge cycle using results of comparing respective voltage levels of the generated rising and falling ramp signals.

Phase regulation in a peak current mode power converter

A regulator circuit that employs coupled inductors with on-time modulation is disclosed. The regulator circuit includes a driver circuit coupled via first and second inductors to a power supply node of a load circuit, and may charge the power supply node via the first inductor for a first charging period, and charge the power supply node via the second inductor for a second charging period. A control circuit may determine durations of the first and second charging periods using respective pluralities of currents.

On-time modulation for phase locking in a buck converter using coupled inductors

Systems, apparatuses, and methods for efficiently generating a stable output voltage for one or more components are described. In various embodiments, current sensing circuitry within a power converter includes one or more current mirrors in addition to at least a first resistor, a second resistor, a switch and a bias current source. The sizes of these latter components scales the sensing current output of the current sensing circuitry from a value of an inductor current flowing through the low pass filter output of the power converter. In addition, the sizes generate an offset which maintains the sensing current as a positive value even when the inductor current becomes a negative value. The boosted sensing current makes a zero detection function and a protection function for the power converter relatively simple with current comparisons.

Systems and methods for sensing current in a power converter

A voltage regulator having a pre-regulator circuit is disclosed. A low dropout (LDO) voltage regulator includes an amplifier circuit, a current buffer circuit, and a pre-regulator circuit. The current buffer circuit includes a transistor having a gate terminal coupled to the amplifier output. The current buffer provides a current based at least in part on the output signal generated by the amplifier. The pre-regulator circuit is coupled to provide a dynamic supply voltage to the current buffer. They dynamic supply voltage depends at least in part on a fixed supply voltage provided thereto, as well as the output voltage provided by the LDO voltage regulator.

High current LDO voltage regulator with dynamic pre-regulator

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 loop, implementing a phase-locked loop control scheme, is configured to adjust the on-time of the high-side switch so as to regulate the switching frequency to be equal to or be proportional to the reference frequency.

Buck DC-DC converter with fixed frequency

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 control the switching of the power switches. The buck switching regulator generates an output voltage with increased accuracy and fast transient response. Furthermore, the buck switching regulator can be used with output capacitor having any value of ESR.

Hysteretic buck DC-DC converter

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 circuit generating a second feedback signal indicative of the regulated output voltage; and an operational transconductance amplifier (OTA) configured to receive the second feedback signal and the first reference signal and to generate an output signal. The output signal of the OTA is coupled to the comparator to adjust an offset to the comparator so as to cancel the offset at the regulated output voltage due to the injected ripple signal.

Buck DC-DC converter with accuracy enhancement

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.

Buck DC-DC converter with improved accuracy

A filter circuit in a phase-locked loop circuit includes a capacitor coupled between a control voltage node and a first node; and a variable resistive element coupled between the first node and a ground potential. The variable resistive element has a resistance value modulated by a current proportional to the charge pump current of the charge pump. In one embodiment, the variable resistive element is a MOS transistor biased in the linear region and having a drain-to-source resistance modulated by the current proportional to the charge pump current.

Phase-locked loop having a constant damping ratio

A PLL including an adaptive loop filter. The PLL includes a feedback circuit which provides a feedback signal based on an output signal and a phase detector generating an adjust signal based on a frequency of the feedback signal compared with a reference frequency. A charge pump receives the adjust signal and provides a control voltage. The adaptive loop filter includes a capacitor and an adaptive resistance with a current control input. A VCO has an output providing the output signal based on a voltage level of the control voltage. A bias generator converts the control voltage to a loop bias current, and has a bias output based on the loop bias current coupled to the current control input of the adaptive resistance. The bias output of the bias generator may also be used to control the charge current and the VCO using currents proportional to the loop bias current.

Phase locked loop with adaptive loop filter

A buck switching regulator includes a feedback control circuit including a first gain circuit configured to generate a first feedback signal indicative of the regulated output voltage; a ripple generation circuit configured to generate a ripple signal using the switching output voltage and to inject the ripple signal to the first feedback signal; a second gain circuit configured to generate a second feedback signal indicative of the regulated output voltage; an operational transconductance amplifier (OTA) configured to generate an output signal having a magnitude indicative the difference between the second feedback signal and the first reference signal; and a comparator configured to generate a comparator output signal having an output level indicative of the difference between the output signal of the OTA and the first feedback signal. As thus configured, the buck switching regulator generates an output voltage with increased accuracy and fast transient response.

Buck DC-DC converter with dual feedback control

A phase locked loop including first and second charge pumps, a voltage buffer and a bias generator for adaptive biasing for improved performance. A voltage controlled oscillator, feedback circuit and phase detector portions may be provided to operate similar to conventional configurations. The first charge pump receives an adjust signal, such as from the phase detector, and selectively charges an intermediate node. The second charge pump receives the adjust signal and selectively charges a control node developing the control voltage for the VCO. A loop filter capacitor is referenced to the intermediate node. The voltage buffer, replacing the loop filter resistor, buffers the intermediate node and drives the control node. The bias generator converts the control voltage to a converter bias current based on the control voltage and adjusts the charge pump currents and a bias current of the voltage buffer.

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Austin, TX, United States of America

Dashun Xue