# US 5,708,434 A · Resistor string digital/analog converter with resetting switches > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,708,434 A - Document ID: US5708434A - Status: Granted - Kind: A - Application number: 08/706,535 - Filed: 1996-09-05 - Granted: 1998-01-13 - Earliest claimed: 1995-09-06 - Assignees: NEC Corporation - Inventors: Hiroshi Hasegawa - Web page: https://patentgrep.com/patent/US5708434A ## CPC - H03M 1/08: of noise {(H03M1/0617 takes precedence)} - H03M 1/168: {and delivering the same number of bits} - H03M 1/76: using switching tree - 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 In a digital/analog (D/A) converter, a plurality of resistors are connected in series between first and second power supply voltage terminals, and a plurality of switches are arranged in a tree configuration between first nodes of the resistors and an output terminal. The switches are turned ON and OFF in response to input bits. At least one reset switch is connected to a second node of at least one of the switches on a side of said output terminal, thus resetting the second node to a predetermined voltage. ## Claims ### Claim 1 A digital/analog (D/A) converter comprising: first and second power supply voltage means; an output terminal; a plurality of resistors connected in series between said first and second power supply voltage means; a plurality of switches arranged in a tree configuration between first nodes of said resistors and said output terminal, said switches being turned ON and OFF in response to input bits; and at least one reset switch, connected to a second node of at least one of said switches on a side of said output terminal, for resetting said second node to a predetermined voltage. ### Claim 2 (depends on 1) The D/A converter as set forth in claim 1, wherein said reset switch is connected to one of the first nodes of said resistors, for resetting said second node to a voltage at said one of the first nodes of said resistors. ### Claim 3 A digital/analog (D/A) converter comprising: first and second power supply voltage means; an output terminal; a plurality of first resistors connected in series between, said first and second power supply voltage means, each of said first resistors including a pair of second resistors in series; a plurality of switches arranged in a tree configuration between first nodes of said first resistors and said output terminal, said switches being turned ON and OFF in response to input bits; and a plurality of reset switches, each connected between one second node of said pair of second resistors and one node of one of said switches on a side of said output terminal. ### Claim 4 An analog/digital (A/D) converter apparatus comprising: at least first and second A/D converters, said first A/D converter performing an A/D conversion upon an analog input voltage; and at least one digital/analog (D/A) converter, connected to said first A/D converter, for performing a D/A conversion upon output bits of said first A/D converter, said second A/D converter performing an A/D conversion upon a difference between said analog input voltage and an analog output voltage of said D/A converter, said D/A converter comprising: first and second power supply voltage means; an output terminal; a plurality of resistors connected in series between said first and second power supply voltage means; a plurality of switches arranged in a tree configuration between first nodes of said resistors and said output terminal, said switches being turned ON and OFF in response to the output bits of said first A/D converter; and at least one reset switch, connected to a second node of at least one of said switches on a side of said output terminal, for resetting said second node to a predetermined voltage. ### Claim 5 (depends on 4) The A/D converter apparatus as set forth in claim 4, wherein said reset switch is connected operatively to an input of said first A/D converter, for resetting said second node to said analog input voltage. ### Claim 6 (depends on 4) The A/D converter apparatus as set forth in claim 4, wherein said reset switch is tuned ON before said D/A converter performs said D/A conversion upon the output bits of said first A/D converter. ### Claim 7 (depends on 4) The A/D converter as set forth in claim 4, further comprising at least first and second sample/hold circuits each connected to inputs of said first and second A/D converters, respectively, said first and second A/D converters being pipelined. ### Claim 8 (depends on 4) The A/D converter as set forth in claim 4, further comprising a sample/hold circuit connected to an input of said first A/D converter, said first and second A/D converters being not pipelined. ### Claim 9 An analog/digital (A/D) converter apparatus comprising: first and second A/D converters for performing A/D conversions upon an analog input voltage; and a digital/analog (D/A) converter, connected to said first and second A/D converters, for applying first and second comparison reference voltages to said first and second A/D converters, respectively, said D/A converter comprising: first and second power supply voltage means; a plurality of output terminals for generating said second comparison reference voltages; a plurality of first resistors, connected in series between said first and second power supply voltage means, for generating said first comparison reference voltages, each of said first resistors including a plurality of second resistors in series; a plurality of switches arranged in a tree configuration between first nodes of said second resistors and said output terminals, said switches being turned ON and OFF in response to output bits of said first A/D converter; and a plurality of reset switches, each connected to one second node of one of said switches on a side of said output terminals. ### Claim 10 (depends on 9) The A/D converter apparatus as set forth in claim 9, wherein said reset switches are connected operatively to inputs of said first and second A/D converters for resettling said second node to said analog input voltage. ### Claim 11 (depends on 9) The A/D converter apparatus as set forth in claim 9, wherein said reset switches are turned ON before said D/A converter is operated.