Digital-to-analog converter
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsKurumi Nakayama, Yasuyuki Doi
Life of this patent
Estimating the term…
Abstract
For example, in order to convert a 6-bit digital signal into an analog signal, a reference voltage generating circuit for generating 17 reference voltages, a first switch circuit having 19 switch pairs each including a MOS transistor for two reference voltages adjacent to each other in accordance with upper four bits, a second switch circuit including a series circuit of 12 MOS transistors and for dividing the difference between the two selected reference voltages using combined ON-resistances into four so as to obtain three intermediate voltages, and a third switch circuit for selectively outputting the lower voltage of the two selected reference voltages or one of the three intermediate voltages in accordance with lower two bits, are provided.
Claims14
A converter for converting a digital signal having N bits (N is an integer of 3 or more) into an analog signal using a plurality of reference voltages different from each other, comprising:
- a selective voltage dividing circuit having a plurality of MOS transistors functioning as switches, and for selecting two reference voltages of the plurality of reference voltages via the same number of MOS transistors of the plurality of MOS transistors in accordance with upper (N−m) bits of the digital signal, and dividing a difference between the two selected reference voltages into M using combined ON-resistances of M MOS transistor groups connected in series to each other of the plurality of MOS transistors to obtain (M-1) intermediate voltages, wherein M is any one of integers from 2m to 2m-1+1 where m is an integer of 1 or more;
- and
- an output circuit for selectively outputting one of the two selected reference voltages or one of the (M−1) intermediate voltages in accordance with lower m bits of the digital signal.
Dependencies are inferred from the claim text.