| Today,with the rapid development of integrated circuit and communication technology,various electronic products such as mobile phones,smart watches,and notebooks are emerging in an endless stream.Meeting the requirements of auditory effects while providing functions such as call,playback,navigation,and voice wake-up,has become a major new selling point for modern electronic products.However,most widely used high-precision audio processing chips,such as Sigma-Delta ADC(Analog to Digital Converter),only support single audio processing and fixed frequency output,with low flexibility.The improved methods for this application scenario have certain limitations.Therefore,multiple chips are commonly used in portable devices to simultaneously process audio data from different channels,which increases the volume,cost,and power consumption of the product.Therefore,this article focuses on the implementation of multi-channel audio processing and different audio quality adjustment in Sigma-Delta ADC chips.This article proposes a multimode scheme for the digital filter chip in Sigma-Delta ADC to simultaneously process audio data from multiple channels and different tasks,to reduce the volume and cost of electronic products,and improve the equipment’s endurance.The main research content and innovation points of this article are summarized as follows:(1)Aiming at the problems of poor adjustability and difficulty in removing low-frequency noise when current audio Sigma-Delta ADC chips process different audio frequencies,a new four-stage cascade decimation filter structure with adjustable sampling rate is proposed.Compared to traditional four stage cascade decimation filters,using CIC(Cascade Integrator Comb)filters with adjustable decimation rates to achieve the output of variable frequency audio signals improves processing flexibility.By replacing the FIR(Finite Impulse Response)filters used in traditional methods with cascaded IIR(Infinite Impulse Response)filters,the chip’s noise reduction ability in the low frequency region is improved,the filter order is reduced,and the hardware structure is simplified.(2)Aiming at the current functional requirements of multi audio processing,an 8-channel dynamic filtering processing structure is designed.Integrating eight sets of four stage filtering structures into a single Sigma-Delta ADC chip has stronger processing power compared to traditional single channel audio Sigma-Delta ADC chips.Compared with existing 4,6,and 8 channel audio processing chips,it adds independent audio quality adjustment functions for each channel,making it more suitable for application scenarios that handle different audio tasks.(3)Aiming at the complex control methods of multi audio parallel processing and independent adjustment of each channel,a mode configuration method based on IPS(IP Interface Standard)bus is proposed.Fast access to CHEN,OSR,and QSEL bits in registers through a bus interface enables the opening and closing of any channel,as well as the control of output sound quality and switching of operating modes under different tasks.Compared with the method of directly manipulating registers,it simplifies the configuration steps and facilitates chip integration.(4)In order to more fully verify the design of this article,Python and VCS are used to verify the filtering performance,and build a dedicated UVM(Universal Verification Methodology platform)platform to verify the function of the module.Use 16nm process library for synthesis,with an area of 50638.417366μm2 and a maximum signal to noise ratio of 122.73dB.Compared with other research results in recent years,the design area and signal-tonoise ratio in this article are superior to most design schemes.In terms of functional comparison,the multi-channel and multimode improvement scheme of the digital filter chip in the audio Sigma-Delta ADC in this article is more suitable for the needs of portable consumer electronics for multiple audio processing. |
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