# US 5,351,048 A · One bit high speed signal processing system utilizing controlled spectrum of quantization noise > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,351,048 A - Document ID: US5351048A - Status: Granted - Kind: A - Application number: 07/866,316 - Filed: 1992-04-09 - Granted: 1994-09-27 - Earliest claimed: 1992-04-09 - Inventors: Yoshio Yamasaki - Web page: https://patentgrep.com/patent/US5351048A ## CPC - H03M 3/476: {Non-linear conversion systems} - H03M 3/50: {Digital/analogue converters using delta-sigma modulation as an intermediate step (digital delta-sigma modulators per se H03M7/3004)} - H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C) ## Abstract A 1-bit high speed method for analog-to-digital and digital-to-analog conversion of an analog input signal of a given form is provided for accomplishing a more accurate digital-to-analog conversion of a digitized signal at a higher speed and over a wider frequency range at a comparable data rate to relatively lower speed and narrower frequency range conventional systems. The method comprises the steps of emphasizing the analog input signal to form a high frequency emphasized signal; processing the emphasized signal to form a 1-bit digital signal; and low pass filtering the digital signal to obtain an analog signal of a form substantially the same as the form of the analog input signal without use of a multi-bit dequantizer for digital-to-analog conversion. The invention also provides a novel 1-bit, high speed processing system for carrying out the foregoing method. ## Claims ### Claim 1 A 1-bit high speed analog-to-digital and digital-to-analog conversion system for improved digital-to-analog conversion at higher speed and over a wider frequency range comparable to relatively lower speed and narrower frequency range conversion systems, said system comprising: input circuit means for receiving an analog input signal; analog-to-digital conversion means for quantizing said analog input signal using a controlled spectrum of quantizing noise to produce a 1-bit high speed digital signal so that quantization noise of said 1-bit high speed digital signal is concentrated at a high frequency band, the frequency of the high frequency band being higher than the frequency band of said analog input signal; and digital-to-analog conversion means for receiving and band-limiting said 1-bit high speed digital signal to produce an analog output signal of a form substantially similar to the form of the analog input signal, wherein said analog-to-digital conversion means comprises: an integration circuit, comprising a plurality of cascaded integrators, for integrating the analog input signal, a 1-bit quantizer connected to the integration circuit for quantizing the output signal of the integration circuit, and a delay circuit for delaying the output signal of the 1-bit quantizer and supplying the delayed signal to the integration circuit. ### Claim 2 (depends on 1) A system according to claim 1, further comprising an emphasis circuit interposed ahead of said analog-to-digital conversion means for amplifying said analog input signal in a predetermined frequency band and a de-emphasis circuit following said digital-to-analog conversion means for attenuating said analog output signal in the predetermined frequency band. ### Claim 3 (depends on 1) A system according to claim 1, wherein said analog-to-digital conversion means further comprises a plurality of feedback loops provided in the integration circuit. ### Claim 4 (depends on 1) A system according to claim 1, wherein said digital-to-analog conversion means comprises a low pass filter circuit. ### Claim 5 (depends on 1) A system according to claim 1, further comprising processing means for conducting a predetermined processing of said 1-bit high speed digital signal. ### Claim 6 (depends on 5) A system according to claim 5, wherein said predetermined processing comprises recording said 1-bit high speed digital signal onto a recording medium and reproducing the recorded signal. ### Claim 7 A 1-bit high speed analog-to-digital and digital-to-analog conversion method for accomplishing an improved digital-to-analog conversion at higher speed and over a wider frequency range comparable to relatively lower speed and narrower frequency range conversion systems, said method comprising the steps of: receiving an analog input signal; quantizing said analog input signal using a controlled spectrum of quantizing noise to produce a 1-bit high speed digital signal so that quantization noise of said 1-bit high speed digital signal is concentrated at a high frequency band, the frequency of the high frequency band being higher than the frequency band of said analog input signal; and receiving said 1-bit high speed digital signal and band-limiting said 1-bit high speed digital signal to produce an analog output signal of a form substantially similar to the form of the analog input signal, wherein said analog-to-digital conversion step comprises the steps of: integrating the analog input signal using a plurality of cascaded integrators, quantizing the integrated signal by a 1-bit quantizer connected to the integrators, and delaying the output signal of the 1-bit quantizer and supplying the delayed signal to the integrators. ### Claim 8 (depends on 7) A method according to claim 7, further comprising the steps of: emphasizing said analog input signal in a predetermined frequency band before quantizing the same; and de-emphasizing said analog output signal in the predetermined frequency band. ### Claim 9 (depends on 7) A method according to claim 7, further comprising conducting a predetermined processing of said 1-bit high speed digital signal. ### Claim 10 (depends on 9) A system according to claim 9, wherein said predetermined processing comprises recording said 1-bit high speed digital signal onto a recording medium and reproducing the recorded signal. ### Claim 11 (depends on 7) A method according to claim 7, wherein said band-limiting step further includes de-emphasizing said analog output signal in the predetermined frequency band. ### Claim 12 (depends on 7) A method according to claim 7, wherein said converting step comprises low pass filtering said analog output signal.