Patent ID: 6333709
Filing Date: 2001-12-25
Classification: G06F,H03K,H03M

Abstract:
A sequential analog/digital converter comprising:an N bit analog/digital conversion unit having an input terminal for which analog input is provided and N (N is a plural number) bits output terminals, for which binary output is provided, said conversion unit comprising:N unit circuits arranged in parallel, each including:an input capacitor having one electrode connected to said input terminal;a first inverter connected to the other electrode of said input capacitor; anda second inverter connected to said first inverter,wherein outputs of said second inverters of said unit circuits are respectively provided for said output terminals,wherein inverted outputs of said outputs for said unit circuits are fed back via feedback capacitors to inputs of said first inverters of said unit circuits respectively corresponding to lower bits, andwherein a capacitance of said feedback capacitor, which corresponds to said inverted output of the M-th (M is an integer) unit circuit from the most significant bit, is of 1/2.sup.M of a capacitance of said input capacitor of said unit circuit that is fed back;said converter further comprising:a remainder input capacitor, one electrode of which is connected to said input terminal;an amplifier for amplifving a voltage at the other electrode of said remainder input capacitor (2.sup.N+1 -1) times; anda remainder output terminal, for which the output of said amplifier is provided,wherein said inverted output of said output for each of said unit circuits is supplied via a remainder feedback capacitor to an input terminal of said amplifier, and a capacitance of said remainder feedback capacitor, which corresponds to said inverted output of an M-th unit circuit from the most significant bit, is 1/2.sup.M times of a capacitance of said remainder input capacitor;a sample-and-hold circuit for sampling and holding an analog input and for transmitting a hold value to said N bit analog/digital conversion unit; andswitch means for transmitting, to said sample-and-hold circuit, a remainder output of said analog/digital conversion unit.