摘要:
A switching amplifier drives a load or audio transducer. A digital integral noise shaping circuit converts a digital input such as audio content to an output digital pulse width modulated signal using an integrator. The integrator integrates the digital input, a variable frequency reference pulse width modulated signal and an inverse of the output digital pulse width modulated signal. A half bridge amplifier receives the output digital pulse width modulated signal and drives the load or audio transducer. A variable frequency generator generates the variable frequency reference pulse width modulated signal with an approximately equal duty ratio or alternatively varies the variable frequency pulse width modulated signal above and below about a fifty percent duty ratio.
摘要:
A system and method for analog-to-digital conversion using digital pulse width modulation (PWM) is disclosed. The method and system according to the disclosed invention converts an analog input signal to a digital signal in pulse code modulated (PCM) form. The disclosed invention uses a feedback circuit to perform PWM of the analog input signal. The PWM signal is then decimated to obtain the digital signal in PCM form. The system according to the disclosed invention requires lower operating frequency and dissipates lesser power than prior art systems providing the same sampling frequency and resolution. The operation at a lower frequency is achieved by obtaining two samples from every pulse of the PWM signal; the first sample being obtained from the right duty ratio, and the second sample being obtained form the left duty ratio. Further, the disclosed invention has lesser implementation complexity and higher signal-to-noise ratio than prior art.
摘要:
A circuit (104, 106) includes a comparison circuit (202, 504, 506, 602) and a correction circuit (204, 508, 510, 604). The comparison circuit provides a comparison signal (212, 524, 526, 612) in response to an error value (210, 520, 522, 610) and a reference value (214). The error value is based on a pulse modulated input signal (114) and a pulse modulated output signal (118). The correction circuit asynchronously provides a corrected pulse modulated signal (116) by selectively delaying and advancing an edge of the pulse modulated input signal based on the comparison signal. The pulse modulated output signal is based on the corrected pulse modulated signal.
摘要:
A system for a continuous time noise shaping analog-to-digital converter (“ADC”) with a suppressed carrier pulse width modulated (“PWM”) quantizer is disclosed. In particular, a suppressed carrier feedback signal may expand the dynamic range of a sigma delta modulated ADC and enhance the stability of the noise shaping loop.
摘要:
A system for a continuous time noise shaping analog-to-digital converter (“ADC”) with a suppressed carrier pulse width modulated (“PWM”) quantizer is disclosed. In particular, a suppressed carrier feedback signal may expand the dynamic range of a sigma delta modulated ADC and enhance the stability of the noise shaping loop.
摘要:
A method for preserving phase information during quantization of pulse width modulation (PWM) signals used in power system applications. In one embodiment, a digital audio amplifier (12) implements a method of noise shaping, where the quantization error is used in coordination with a noise shaping filter (64) to remove the noise from the desired baseband of the output. A phase-preserving expression is used to provide additional information for generating the amplified output (40). In one embodiment, the filter (64) includes a series of integrators (70, 72), where non-linear integration terms are added at each stage of integration to provide the phase information. In one embodiment the filter is implemented in software to run on a digital signal processor, and in another the filter is implemented in a hardware accelerator.
摘要:
The subject disclosure is directed towards preventing the exploitation by malicious code of object state corruption vulnerabilities, such as use-after-free vulnerabilities. An object class is configured with a secret cookie in a virtual function table of the object, e.g., inserted at compile time. An instrumentation check inserted in the program code evaluates the secret cookie to determine whether the object state has been corrupted before object access (e.g., a call to one of the object's methods) is allowed. If corrupted, access to the object is prevented by the instrumentation check. Another instrumentation check may be used to determine whether the object's virtual table pointer points to a location outside of the module that contains the legitimate virtual function table; if so, object access is prevented.
摘要:
A converter continuously converts an input signal (110) to an output signal (112) even during correction and compensation. A primary converter (124) converts the signal along a forward primary path (104). A feedback converter (140) along a feedback path (106) outputs a feedback signal (116). A reference device (136) employs reference indicator (134) to provide a digital reference signal (135). A selection device (132) passes the digital reference signal (135) to an element (204) of the feedback converter (140) for outputting reference portion (208) of the feedback signal (116). The passing of the digital reference signal (135) to the element (204) is contemporaneous with the converting of the input signal (110) to the output signal (112). The evaluator (142) determines a conversion characteristic of the element (204) by employing a characteristic of the reference indicator (134).
摘要:
The subject disclosure is directed towards preventing the exploitation by malicious code of object state corruption vulnerabilities, such as use-after-free vulnerabilities. An object class is configured with a secret cookie in a virtual function table of the object, e.g., inserted at compile time. An instrumentation check inserted in the program code evaluates the secret cookie to determine whether the object state has been corrupted before object access (e.g., a call to one of the object's methods) is allowed. If corrupted, access to the object is prevented by the instrumentation check. Another instrumentation check may be used to determine whether the object's virtual table pointer points to a location outside of the module that contains the legitimate virtual function table; if so, object access is prevented.
摘要:
An analogue-to-digital converter apparatus comprises a first integrator coupled to a second integrator. The first and second integrators are coupled so as to provide a complex pole. The first integrator is selectively electrically decoupleable from the second integrator, thereby removing the complex pole.