Switched capacitor D/A converter

Claim 1

A digital-to-analog converter (DAC) for converting a set of N data bits to an analog voltage comprising: N capacitors (CO-C5), one capacitor for each one of said N data bits; each capacitor having first and second plates; and means connecting the first plate of each capacitor to an output node; characterized by: N switching transistors (M26-M25) one for each one of said N data bits, each one of said N switching transistors having first and second electrodes defining the ends of a conduction path and a gate electrode, each gate electrode having associated therewith a relatively small capacitance; means connecting the conduction path of each switching transistor between the second plate of its associated capacitor and a first power terminal (ground); an input node (3) adapted to receive serially supplied digital data signals during a data load interval and a precharge signal during a precharge interval; N selectively enabled data transfer paths, (M10, M30, ...M15,M35) one data transfer path per each one of said N switching transistors, each data transfer path connected between said input node and the gate electrode of its associated switching transistor; means (CSj;BO-B5) for selectively turning-on said N data transfer paths, one at time, during said data load interval for selectively sampling the digital data signals and for applying and storing a voltage corresponding to each one of said digital data signals on the gate of a corresponding one of said N switching transistors; and means (M3) for selectively applying a voltage across said capacitors for charging them in accordance with the data responsive voltage levels present on the gate of their respective switching transistors.