| 摘要 |
1. Integrated voltage divider consisting of a series arrangement of a number (N) of resistors (R0, R1...R8, Rr), operated from a biasing voltage (Ur), with the tapping points thereof, each via a switching connection consisting of one individual switching transistor or a series arrangement of switching transistors, and in dependence upon a digital selecting signal (A...D), capable of being connected through to the voltage output (U) by means of a selection circuit, with said selection circuit, said resistors (R...) and said switching connections being materialized by employing transistors according to the insulated-gate field-effect transistor technique, characterized by the combination of the following features : - each switching connection is realized by the switching section of one single switching transistor (T1...T8) of the one channel conductivity type (n-channel in the drawings), - the selection circuit consists of a 1-ex-n-short-circuit decoder (KD) and of a 1-ex-n-open circuit decoder (SD) whose like inputs are arranged in parallel and supplied with the corresponding bits (A...D) of the selecting signal, - the open-circuit decoder (SD) consists only of transistors of the one channel conductivity type which are arranged in the semiconductor body of the integrated voltage divider as connected to the reference potential (UO) of the source of biasing voltage (Ur), ans its potential input is connected to the reference potential (UO), - the short-circuit decoder (KD) consists only of transistors of the other channel conductivity type (p-channel in the drawings), which are arranged within a separate insulating island (NW) of the one channel conductivity type, and its potential input is connected to this insulating island (NW) ans to the operating voltage (Ud), and - like outputs (1...8) of both the open-circuit and the short-circuit decoders (SD, KD) are connected to one another and to the respective gate of the switching transistors (T...). |
