A/D and D/A converter using C-2C ladder network

DETAILED DESCRIPTION It is therefore an object of the present invention to provide A/D and D/A converters employing a capacitor ladder network which may be manufactured using monolithic, integrated circuit fabrication techniques and which can be trimmed electrically.
The foregoing and other objects are attained by providing a capacitor ladder network formed as a multilayer structure that includes a substrate, diffusion regions in the substrate, a polysilicon layer and an aluminum layer wherein the capacitances are formed between the aluminum layer and the polysilicon layer and between the polysilicon layer and the diffusion regions such that the capacitances are in the ratio of 2C-C.
In addition, trimming networks are provided which comprise a series of parallel capacitors formed by the diffusion regions in the substrate and the polysilicon layers.
After the capacitor ladder network has been manufactured using monolithic, integrated circuit techniques, the trimming capacitors can be connected or disconnected using a laser technique to electrically trim the capacitor ladder network.