| 摘要 |
An R-2R-ladder network has n chained ladder cells, each controlled by an associated one of n control circuits wherein n corresponds to the number of digits of a digital signal to be converted. Each cell is composed of a series transistor inserted between two neighboring nodes of the ladder network and of a first, a second and a third cross transistor. The cross transistors are commonly connected by one main electrode to form a star circuit. The first, second and third cross transistors are connected by a second main electrode to the node of the cell, to a sum current output line and to ground, respectively. The gates of the series transistor and of the first cross transistor are directly connected to a reference voltage source whereas the gates of the second and the third cross transistor of each ladder cell are connected to a respective one of two signal outputs of the associated control circuit. Each control circuit has a signal input for receiving a digit of the digital input signal dependent upon which state the control circuit is operated to shunt the reference voltage alternatively to one of both signal outputs. |
