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公开(公告)号：US11451215B1
公开(公告)日：2022-09-20
申请号：US17343084
申请日：2021-06-09
Inventor： Miao Song , Xin Zhao , Tejasvi Das , Jason Wardlaw , Michael A. Kost
Abstract: A piece-wise linear (PWL) waveform generator includes a current generator that generates a reference current, an output capacitor across which an output voltage is developed to form a PWL waveform, charging and discharging current sources for charging/discharging the output capacitor based on the reference current, a clock-controlled switch network for controlling the charging/discharging of the output capacitor, and a feedback control loop that senses the output voltage and controls the current generator to vary the reference current based on the output voltage. A first switch controlled by a first clock signal periodically connects/disconnects a current source output to/from a load impedance and a second switch controlled by a second clock signal periodically connects/disconnects a capacitor to/from the current source while disconnected from the load impedance. The capacitor capacitance is based on a predetermined voltage to mitigate glitching when the first switch connects the current source output to the load impedance.
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公开(公告)号：US11206487B2
公开(公告)日：2021-12-21
申请号：US16709075
申请日：2019-12-10
Inventor： John Paul Lesso , Mark James Mccloy-Stevens , John Bruce Bowlerwell , Yanto Suryono , Xin Zhao , Morgan Timothy Prior
Abstract: This application relates to audio driving circuitry (100), and in particular to audio driving circuitry for outputting first and second audio driving signals for driving a stereo audio load (106), which may be a stereo audio load of an accessory apparatus (102) removably coupled to the audio driving circuitry in use. A load monitor (111) is provided for monitoring to monitor, from a monitoring node (112), an indication of a common mode return current passing through a common return path, together with an indication of a common mode component of the first and second audio driving signals and to determine an impedance characteristic of the stereo audio load. The load monitor (111) can provide dynamic monitoring of any significant change in load impedance. In some embodiments the load monitor (111) comprises an adaptive filter (301) which adapts a parameter of the filter which is related to the load impedance so as to determine the indication of load impedance.
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公开(公告)号：US10763811B2
公开(公告)日：2020-09-01
申请号：US16181762
申请日：2018-11-06
Inventor： Lei Zhu , Tejasvi Das , John L. Melanson , Wai-shun Wilson Shum , Jing Bai , Xin Zhao , Xiaofan Fei
Abstract: A system may include a digital modulator configured to modulate an input signal received at an input of the digital modulator to generate a modulated input signal at an output of the digital modulator, a digital gain element having a digital gain and coupled to the digital modulator, an open-loop Class-D amplifier coupled to an output of the digital modulator and configured to amplify the modulated input signal, wherein the open-loop Class-D amplifier is powered from a variable power supply having a variable supply voltage which is variable in response to one or more characteristics of the input signal, and a control circuit configured to control the digital gain to approximately cancel changes in an analog gain of the open-loop Class-D amplifier due to variation in the variable supply voltage in response to the one or more characteristics of the input signal.
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公开(公告)号：US10663531B2
公开(公告)日：2020-05-26
申请号：US16156069
申请日：2018-10-10
Inventor： Lei Zhu , Jing Bai , Xiaofan Fei , Xin Zhao
Abstract: An apparatus detects a short of a class-D amplifier. A pulse detector detects an output PWM pulse exceeds a predetermined width and a controller differentiates whether the pulse width exceeding is caused by a short or by a large digital input signal occurring during normal operation based on an expected level of the digital input signal to a level of the digital input signal when the pulse width exceeds the predetermined width. The expected level is dynamically obtained in response to one or more previous PWM pulses exceeding the predetermined width during the normal operation and may be selected based on an amount the pulse exceeds the predetermined width. A lookup table of predetermined levels, selected based on impedance of a load, provides the expected level if the expected level has not yet been dynamically obtained when the pulse width exceeds.
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公开(公告)号：US10594310B2
公开(公告)日：2020-03-17
申请号：US16144104
申请日：2018-09-27
Inventor： Ku He , Tejasvi Das , Xin Zhao , Xiaofan Fei
Abstract: A method may include, in a system comprising a digital PWM subsystem having a tunable digital gain, a first path coupled to an output of the digital PWM subsystem and configured to drive an open-loop driver stage, and a second path coupled to the output of the digital PWM subsystem and configured to drive a closed-loop driver stage having a tunable analog gain: selecting one of the first path and the second path for processing an input signal to generate an output signal based on one or more characteristics of the input signal, setting the digital gain to a maximum digital gain and the analog gain to a minimum analog gain when the input signal is lesser than a first threshold, setting the digital gain to a minimum digital gain and the analog gain to a maximum analog gain when the input signal is greater than a second threshold magnitude, and varying the analog gain and the digital gain when the input signal is in a range greater than the first threshold and lesser than a second threshold.
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Patent Agency Ranking
公开(公告)号：US20200058326A1
公开(公告)日：2020-02-20
申请号：US16103288
申请日：2018-08-14
Inventor： Ku He , Tejasvi Das , Xin Zhao , Xiaofan Fei
IPC: G11B27/034 , G11B27/19
Abstract: A polymorphic playback system is disclosed in which one or more parameters of a signal path of the polymorphic playback system are varied based on one or more characteristics of a playback signal processed by the signal path, wherein the polymorphic playback system may include a lower-latency detection filter, a higher-latency detection filter, and a control subsystem that uses the lower-latency detection filter for detecting the one or more first characteristics of the playback signal and uses the higher-latency detection filter for detecting the one or more second characteristics of the playback signal.
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公开(公告)号：US10476444B1
公开(公告)日：2019-11-12
申请号：US16142498
申请日：2018-09-26
Inventor： Tejasvi Das , Xin Zhao , Ku He , Nishant Jain , Lei Zhu , Xiaofan Fei
Abstract: A system may include a plurality of playback paths comprising an open-loop playback path configured to drive an output load and a closed-loop playback path. The closed-loop playback path may include an outer feedback loop comprising one or more integrators, a quantizer, and an output driver for driving the output load, the outer feedback loop having an outer loop feedback gain and an inner feedback loop comprising the one or more integrators and the quantizer and excluding the output driver, wherein the inner feedback loop has a variable inner loop feedback gain which is adjustable to match the outer loop feedback gain.
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公开(公告)号：US10447217B2
公开(公告)日：2019-10-15
申请号：US15884912
申请日：2018-01-31
Inventor： Xin Zhao , Tejasvi Das , Xiaofan Fei , Alan Mark Morton
Abstract: An amplifier may include a first stage configured to receive an input signal at an amplifier input and generate an intermediate signal which is a function of the input signal, and a final output stage configured to generate an output signal which is a function of the intermediate signal at an amplifier output, and a signal feedback network coupled between the amplifier output and input. The final output stage may be switchable among a plurality of modes including at least a first mode in which the final output stage generates the output signal as a modulated output signal which is a function of the intermediate signal, and a second mode in which the final output stage generates the output signal as an unmodulated output signal which is a function of the intermediate signal. Structure of the feedback network and the first stage may remain static when switching between modes.
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公开(公告)号：US10412479B2
公开(公告)日：2019-09-10
申请号：US15154350
申请日：2016-05-13
Inventor： Xin Zhao , Bradley A. Lambert , Xiaofan Fei , Eric J. Swanson
IPC: H04R1/10 , H04R5/04 , H04M1/60 , H03M1/66 , H03M1/12 , G06F1/3287 , G06F3/16 , G06F1/3215
Abstract: A headset power management system provides robust and low-power operation by detecting various connection conditions by measuring a voltage at the microphone terminal with and without injection of current from the headset. A power management circuit controls an operating state of the headset using a microphone terminal voltage detector and can determine whether a short circuit is present indicating a connection to a device that does not have a microphone input, a negative polarity voltage is present indicating that the device may be determining a connection and type of the headset using the microphone terminal, a normal connection, or whether the headset is not connected to a device at all. Depending on the connection state, some or all of the headset electronics may be disabled until a normal connection is detected. For example the microphone processing circuits may be disabled if the connection does not support a microphone input.
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20.发明申请公开(公告)号：US20190199215A1
公开(公告)日：2019-06-27
申请号：US16226454
申请日：2018-12-19
Inventor： Xin Zhao , John L. Melanson , Eric King , Xiaofan Fei
CPC classification number: H02M3/1582 , G05F1/62 , H02M3/157
Abstract: The overall performance of single input multiple output (SIMO) switching DC-DC power converters may be improved by controlling power and output switches to adjust inductor current delivered to one output while maintaining substantially constant the current delivered to other outputs, thereby reducing cross regulation interference across outputs. Power converter systems of this disclosure may be configured to calculate an inductor current value and a duty cycle value based on voltages at each of the voltage outputs. The power converter systems may be configured to control at least one main power switch to increase or decrease the current in the inductor based on the calculated inductor current value. Additionally, the power converter systems may be configured to control at least one output power switch to divert current from the inductor to one of the plurality of output nodes based on the calculated duty cycle value.
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