Patent application number | Description | Published |
20080297382 | PULSE-WIDTH MODULATION OF PULSE-CODE MODULATED SIGNALS AT SELECTABLE OR DYNAMICALLY VARYING SAMPLE RATES - Digital audio circuitry including modulation circuitry ( | 12-04-2008 |
20090319065 | Efficient Asynchronous Sample Rate Conversion - Asynchronous sample rate conversion for use in a digital audio receiver is disclosed. Different algorithms are applied for the upsampling and downsampling cases. In the upsampling case, the input signal is upsampled and filtered, before the application of a finite impulse response (FIR) filter. In the downsampling case, the input signal is filtered by an FIR filter, and then filtered and downsampled. The FIR coefficients of the fractional delay FIR filter are calculated by evaluation of polynomial expressions over intervals of the filter impulse response, at times corresponding to the input sample points. | 12-24-2009 |
20110043398 | CASCADED DAC ARCHITECTURE WITH PULSE WIDTH MODULATION - An embodiment of the invention provides one or more cascade circuits that are cascaded together to form a cascaded circuit. The cascaded circuit reduces noise at an analog output of the cascaded circuit. Each of the cascade circuits contains a noise-shaping circuit, a PCM (Pulse Code Modulation)-to-PWM (Pulse Width Modulation) converter and a 1-bit P-tap AFIR (Analog Finite Impulse Response) filter DAC. Noise at the output of the cascaded circuit may be further reduced by increasing the number of cascade circuits. | 02-24-2011 |
20110267210 | Shaping Inter-Symbol-Interference in Sigma Delta Converter - A signal converting system is described that has a multi-segment digital to analog converter coupled to one or more error shaping loops. Each error shaping loop includes a quantizer with a feedback loop configured to generate a control signal responsive to a stream of symbols and to an error signal. Each error shaping loop also includes an inter-symbol-interference (ISI) shaping loop coupled to receive the control signal and to produce an ISI portion of the error signal that is responsive to inter-symbol transition rate. | 11-03-2011 |
Patent application number | Description | Published |
20080297244 | PWM Loop Filter with Minimum Aliasing Error - One embodiment of an apparatus for filtering an electrical signal includes a loop filter with an input and an output that applies a transfer function to a signal at the input. The transfer function has substantially no real part. The loop filter has a dominant pole placed substantially at or above an upper frequency in the frequency range of interest for the loop filter. | 12-04-2008 |
20090028361 | SYSTEM FOR AMPLIFIERS WITH LOW DISTORTION AND LOW OUTPUT IMPEDANCE - System for pulse-width-modulated class D audio amplifiers. In one preferred embodiment an adder is described to generate a difference signal responsive to an input signal and a feedback signal, a pulse-width-modulator coupled to the adder to compare the difference signal to a reference signal and produce a pulse-width-modulated signal based on the comparing, a filter coupled to an output of the pulse-width-modulator, and a loop filter having a first input coupled to the output of the filter and a second input coupled to the input of the filter, the loop filter to generate a feedback signal by applying transfer functions to signals at its inputs. The loop transfer function of the amplifier is minimum aliasing error transfer function. The minimum aliasing error properties provide low distortion and taking the feedback from the output of the filter reduces high frequency output impedance. | 01-29-2009 |
20090077149 | ASYNCHRONOUS SAMPLING RATE CONVERSION - Asynchronous sampling rate converter using multistage oversampling with final stage polyphase filter coefficients approximated by polynomials of the filter index. The approximation polynomial coefficients occupy smaller memory than the polyphase filter coefficients being approximated. | 03-19-2009 |
20090116654 | ON-THE-FLY INTRODUCTION OF INTER-CHANNEL DELAY IN A PULSE-WIDTH-MODULATION AMPLIFIER - A multiple-channel audio processor ( | 05-07-2009 |
20130077794 | Thermal Control of Voice Coils in Loudspeakers - In an embodiment of the invention, the voice coil of an electro dynamic transducer is protected against thermal overload by estimating the temperature of a magnet in the electro dynamic transducer. When a power limit based on the temperature of the magnet and on a predetermined voice coil temperature limit is reached by an audio signal, the power applied to the voice coil is reduced. | 03-28-2013 |
20130077795 | Over-Excursion Protection for Loudspeakers - In an embodiment of the invention, over-excursion of a diaphragm in an electro dynamic transducer is reduced by attenuating low frequency content in an audio signal when the power of an audio signal exceeds a predetermined power limit. The audio signal is used to drive the input of an amplifier and the output of the amplifier drives the electro dynamic transducer. When the audio signal does not exceed a predetermined power limit, the low frequency content in the input audio signal is amplified. | 03-28-2013 |
20130077796 | Thermal Protection for Loudspeakers - In an embodiment of the invention, the voice coil of an electro dynamic transducer is protected by measuring the power of the input audio signal. When a predetermined power limit is reached by the input audio signal, the power of the input audio signal is reduced. | 03-28-2013 |