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Analog digital converter, A/D conversion stage, method for generating digital signal corresponding to analog signal, and method for generating signal indicating conversion error in the A/D conversion stage

  • US 7,889,111 B2
  • Filed: 06/08/2007
  • Issued: 02/15/2011
  • Est. Priority Date: 06/08/2006
  • Status: Expired due to Fees
First Claim
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1. An analog-digital converter comprising:

  • first to N-th A/D conversion stages connected in series, each stage having a stage input and a stage output, each of the first to N-th A/D conversion stages including a sub A/D conversion circuit, a control circuit, a D/A converter and a gain stage, the sub A/D conversion circuit generating a digital signal of a predetermined number of bits in response to a signal from the stage input, the digital signal indicating a conversion result, the control circuit generating a control signal from the digital signal, the D/A converter generating a predetermined voltage in accordance with the control signal, the gain stage having a first input, a second input and an output, the first input of the gain stage receiving the signal from the stage input, the second input of the gain stage receiving one of the predetermined voltage and the signal from the stage input, the output of the gain stage being connected to the stage output, and the number “

    N”

    being 3 or 4;

    an analog input for receiving an analog signal;

    an input switch, connected between the analog input and the stage input of the first A/D conversion stage, for sampling first and second sample analog signals in first and second sampling periods, respectively;

    a cyclic switch, connected between the stage input of the first A/D conversion stage and the stage output of the N-th A/D conversion stage, for providing a path from the N-th A/D conversion stage to the first A/D conversion stage in a cycle period, the cycle period being different from the first and second sampling periods; and

    a digital operational circuit, the digital operational circuit receiving the conversion result from each of the first to N-th A/D conversion stages, the digital operational circuit generating an A/D conversion digital code, and the A/D conversion digital code indicating a analog/digital conversion result;

    wherein the gain stage has first and second capacitors and an operational amplification circuit,the gain stage stores electric charges from the stage input in the first and second capacitors, again stores an electric charge from the stage input in one of the first and second capacitors, rearranges the electric charges using the first and second capacitors and the operational amplification circuit in response to application of the predetermined voltage to one of the first and second capacitors, and rearranges the rearranged electric charges in the first and second capacitors in response to application of the predetermined voltage to another one of the first and second capacitors to generate the operational value in the output of the operational amplification circuit; and

    the gain stage comprises;

    a first switch for connecting one terminal of the first capacitor to the stage input in a first period;

    a second switch for connecting one terminal of the second capacitor to the stage input in the first period;

    a third switch for connecting the one terminal of the first capacitor to the output of the operational amplification circuit in a second period, the second period being different from the first period;

    a fourth switch, connected between the other terminal of the first capacitor and an inverting input of the operational amplification circuit, for disconnecting the other terminal of the first capacitor from the inverting input in a third period, the third period being between the first period and the second period; and

    a fifth switch, connected between the one terminal of the second capacitor and the output of the operational amplification circuit, for connecting the one terminal of the second capacitor to the output of the operational amplification circuit in a fourth period that is different from the first to third periods, andwherein the inverting input of the operational amplification circuit is connected to another terminal of the first capacitor and to another terminal of the second capacitor in the second period, and the output of the operational amplification circuit is connected to the stage output, andwherein the D/A converter provides the predetermined voltage to the one terminal of the second capacitor in the second period and provides the predetermined voltage to the one terminal of the first capacitor in the fourth period.

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