Analog-to-digital converter

Claim 2

An analog-to-digital converter for providing a digital signal at an N-bit resolution, comprising: first means for digitizing analog signals at an M-bit resolution, M being approximately equal to N/2 and including a digital-to-analog converter for providing the analog equivalent thereof; second means for storing M-bit digital signals as digitized by the first means; third means connected for receiving analog signals to be digitized and further connected to the second means to provide an error signal as the difference between the analog equivalent Of the digital signal generated by the first and stored by the second means and an analog signal received directly by the third means and including means to store representation of the sign of the error signal; signal means connected to the third means for amplifying the error signal by a factor corresponding to a factor in the order of 2 M; fourth means for sequentially connecting the first means to receive a digitized analog signal, bypassing the signal means, and to store the resulting digital signal in the second means and to subsequently cause the first means to receive the resulting amplified error signal from the signal means, for the first means to digitize said amplified error signal, and means connected to be responsive to the sign representation for arithmetically combining the content of the second means and of the digitized error signal to obtain an N-bit digital number.

Claim 3

An analog-to-digital converter comprising: first means for digitizing analog signals at an M-bit resolution; second means for forming the amplified difference between an analog information signal and the analog equivalent of an M-bit digital signal as formed by the first means by a factor equivalent to the M-bit resolution and the corresponding scale factor; third means connected to the first and second means for sequentially operating the first and second means and including means for applying in P-steps, P not exceeding M, respectively residual signals formed from the analog information signal and the analog equivalent of digital residual signals formed in previous steps by the first means, the residual signal digitized by the first means during the first step being the unamplified analog information signal itself; and fourth means for arithmetically combining the digital signals as sequentially formed by the first means under control of the third means to provide an N-bit resolution digital equivalent of the analog information signal.

Claim 4

An analog-to-digital converter comprising: first means for digitizing analog signals at an M-bit resolution; second means for forming the amplified difference between an analog information signal and the analog equivalent of an M-bit digital signal as formed by the first means by a factor equivalent to the M-bit resolution and the corresponding scale factor; third means connected to the first and second means for sequentially operating the first and second means and including means for applying in P-steps, P not exceeding M, respectively residual signals formed from the analog information signal and the analog equivalent of digital residual signals formed in previous steps by the first means, the residual signal digitized by the first means during the first step being the unamplified analog information signal itself; and fourth means for arithmetically combining the digital signals as sequentially formed by the first means under control of the third means to provide an N-bit resolution digital equivalent of the analog information signal.

Claim 5

An analog-to-digital converter system for converting an analog input signal to a group of digital output signals at an N-bit resolution comprising: first means for converting an analog input signal to a first resolution group of digital signals and storing said digital signals in a first storage means; second means for producing an analog error signal equal to the difference between the analog equivalent of the first resolution group of digital signals and the input analog signal, said second means including means for amplifying the analog difference signal by a factor having an order of magnitude substantially equivalent to the absolute value of the first resolution group of digital signals; third means operating for connecting the means for amplifying to the first means for substituting the analog difference signal for the analog input signal at the input of the first means so as to cause said first means to convert said difference signal and to store a second group of digital signals representative thereof in a second storage means; and fourth means for arithmetically combining said group of digital signals in the first and second storage means.

Claim 6

An analog-to-digital converter system for converting an analog input signal to a group of digital output signals at an N-bit resolution comprising: first means for converting an analog input signal to a first resolution group of digital signals and storing said digital signals in a first storage means; second means for producing an analog error signal equal to the difference between the analog equivalent of the first resolution group of digital signals and the input analog signal, said second means including means for amplifying the analog difference signal by a factor having an order of magnitude substantially equivalent to the absolute value of the first resolution group of digital signals; third means operating for connecting the means for amplifying to the first means for substituting the analog difference signal for the analog input signal at the input of the first means so as to cause said first means to convert said difference signal and to store a second group of digital signals representative thereof in a second storage means; and fourth means for arithmetically combining said group of digital signals in the first and second storage means.

Claim 7

A converter system as in claim 3, the first means including a single comparator and a first resistance ladder operated for progressively building up the analog equivalent upon sequential generation of digit bits, the second means including a second resistance ladder holding a duplicate of the analog equivalent for production of the error signal as the first means converts the amplified error signal into the second group of digital signals.

Claim 8

A converter as in claim 1, the first means including a single comparator, the third means including a second digital-to-analog converter for holding a duplicate of the digitized analog signal for the first converter to participate in digitization of the error signal.

Claim 9

An analog-to-digital conversion system comprising: a high-speed serial analog-to-digital converter fOr providing for digitizing analog signals applied to its input on a low resolution scale and including a digital-to-analog converter for progressive build up of an analog reference signal upon sequential generation of digit bits by the analog-to-digital converter; a second digital to analog converter responsive to the generated digit bits and providing an analog equivalent signal in representation thereof; signal means for receiving an analog information signal to be converted into digital signals; error signal means connected to the signal means and to the second converter to produce an error signal; an amplifier connected to receive the error signal and amplifying same corresponding to the resolution scale of the high-speed converter; control means operating to connect the signal means directly to the high-speed converter bypassing the amplifier in a first phase of operation, and to connect the amplifier output to the high-speed converter in a second phase of operation, to obtain sequential low-resolution digitization of the analog information and low-resolution digitization of the amplified error signal; and digital means for arithmetically combining the digitized amplified error signals at a reduced position order of the latter, digitized error signals corresponding to a digital elimination of the amplification, for providing a digital output of twice the resolution of the high-speed converter.

Claim 10

An analog-to-digital conversion system comprising: a high-speed serial analog-to-digital converter fOr providing for digitizing analog signals applied to its input on a low resolution scale and including a digital-to-analog converter for progressive build up of an analog reference signal upon sequential generation of digit bits by the analog-to-digital converter; a second digital to analog converter responsive to the generated digit bits and providing an analog equivalent signal in representation thereof; signal means for receiving an analog information signal to be converted into digital signals; error signal means connected to the signal means and to the second converter to produce an error signal; an amplifier connected to receive the error signal and amplifying same corresponding to the resolution scale of the high-speed converter; control means operating to connect the signal means directly to the high-speed converter bypassing the amplifier in a first phase of operation, and to connect the amplifier output to the high-speed converter in a second phase of operation, to obtain sequential low-resolution digitization of the analog information and low-resolution digitization of the amplified error signal; and digital means for arithmetically combining the digitized amplified error signals at a reduced position order of the latter, digitized error signals corresponding to a digital elimination of the amplification, for providing a digital output of twice the resolution of the high-speed converter.