Analog Devices,inc.

Analog Devices Global Unlimited Company

Eric C Gaalaas

Mark Stewart Cantrell

Baoxing Chen

Bikiran Goswami

Ruida Yun

Robert W Adams

Brian Kirk Jadus

David MacDonald Hossack

Jason J Ziomek

Dongwan Ha

Jason Ma

Gabriel Menard

Felix Qin

Methods and apparatus are disclosed for communicating multiple logic states across a digital isolator. The digital isolator is a universal serial bus (USB) isolator in some embodiments. The digital isolator includes one or more single-bit data channels. Three or more logic states of information are transmitted across the single-bit data channel(s). The logic states are distinguished by a pulse sequence, and in particular a number of edges of the pulse sequence and a final value or final edge of the pulse sequence.

Coding schemes for communicating multiple logic states through a digital isolator

A device for providing a reset signal to one or more sequential logic circuits in an electronic system responsive to a supply voltage condition includes a first voltage detector circuit to generate a first pulse after the supply voltage rises to a first threshold voltage level. The device further includes a second voltage detector circuit to generate a second pulse after the supply voltage falls below a second threshold voltage level. The device additionally includes a latch circuit to store a first value based on the first pulse after the supply voltage rises to the first threshold voltage level, disable the first voltage detector circuit after storing the first value, reset to store a second value based on the second pulse after the supply voltage falls below the second threshold voltage level, and to disable the second voltage detector circuit after the resetting.

Low quiescent current power on reset circuit

A receiver system for an on-off key ('OOK') isolator system may include a pair of receivers. A first receiver may generate a first current signal representing a received OOK signal, and a second receiver may generate a second current signal from a common mode representation of the received OOK signal. The receiver system may include circuitry to compare the first and second current signals and generate an output signal therefrom.

Demodulation of on-off-key modulated signals in signal isolator systems

A receiver system for an on-off key ('OOK') isolator system may include a receiver that generates an intermediate current signal based on an OOK input signal. The intermediate current may be provided at a first current level when the input signal has a first OOK state and a second current level when the input signal has a second OOK state. The system also may include an output driver to generate a voltage representation of the intermediate current signal. Performing signal processing in a current domain permits fast transitions between OOK states.

A USB-based isolator system conveys USB signals between a pair of galvanically isolated circuit systems and supports controlled enumeration by a downstream device on upstream USB signal lines. The isolator system provides a multi-mode voltage regulator to support multiple voltage supply configurations. The isolator system further provides control systems for each of the isolated circuit systems and provides robust control in a variety of start up conditions. Additionally, the isolator system includes refresh timers and watchdog mechanisms to support persistent operation but manage possible communication errors that can arise between the isolated circuit systems.

USB isolator with advanced control features

The invention is directed to a multi-bit digital signal isolation system including a plurality of micro-transformers, each having a primary winding and a secondary winding, a transmitter circuit receiving a multi-bit signal and transmitting an encoded logic signal across the plurality of micro-transformers corresponding to the multi-bit signal, the primary winding of each micro-transformer receiving a signal corresponding to one of at least three possible states, and a receiver circuit receiving the encoded logic signal from the secondary windings of the plurality of transformers, decoding the encoded logic signal and reconstructing the received multi-bit signal based upon the decoded signal.

Multi-bit digital signal isolator

Noise reduction for a switching amplifier system having a differential output stage and demodulator filter responsive to complementary PWM signals includes generating in-phase PWM signals and gradually adjusting their duty cycle between a low duty cycle and the full duty cycle of the complementary PWM signals, generating full duty cycle PWM signals and gradually shifting their relative phase between in-phase and out-of-phase; and in response to a turn-on signal, adjusting the in-phase PWM signals from low to full duty cycle and shifting the relative phase from in-phase to out-of-phase, and in response to a turn-off signal shifting the relative phase from out-of-phase to in-phase and adjusting the in-phase PWM signals from full to low duty cycle for maintaining balanced charge on the demodulation filter to reduce audible noise.

Noise reduction system and method for audio switching amplifier

An apparatus for controlling the state variable of an integrator stage in a modulator including a detector circuit for generating an overload signal when the modulator is overdriven, a control circuit responsive to the overload signal for generating switching control signals during the overdriven condition, and an integrating capacitance circuit having an unswitched portion and a switched portion and responsive to the switching signals for repeatedly connecting the switched portion between the unswitched portion and a discharge path to receive and drain charge when the modulator is overdriven to increase the lossiness of the integrator stage and control a state variable of the modulator.

Apparatus and method for controlling the state variable of an integrator stage in a modulator

A sigma delta modulator includes a modulator module that includes a quantizer with variable hysteresis, which receives an input signal to perform necessary modulation operations. A non-linear mapping module receives a signal associated with said input signal and tabulates the necessary hysteresis control information so as to reduce the transition rate of the modulator module.

Growing community of inventors

Bedford, MA, United States of America

Eric C Gaalaas