Capacitor unit for high-precision capacitor array

Abstract

The invention discloses a capacitor unit for a high-precision capacitor array, and the capacitor unit comprises an xth layer of metal, an effective capacitor unit is composed of a middle cross-shaped metal and a peripheral square metal, four quadrants formed by taking the cross-shaped metal as an x axis and a y axis are provided with comb-shaped metals in different directions, and the comb-shaped metals connect the cross-shaped metal and the square metal, x layers of metal are used as a part of a lower electrode plate of the capacitor, and upward through holes are formed in the periphery; and the x-layer redundant capacitor part is the same as the effective capacitor part. The basic structure of the effective capacitor unit is that the peripheral square metal serves as a lower pole plate, the middle cross-shaped metal serves as an upper pole plate, and the comb-shaped structures of the four quadrants are staggered in an interdigitated shape to form a capacitor or are all connected to the peripheral square lower pole plate to serve as a shield. According to the invention, multi-directional effective capacitance can be realized, the upper electrode plate is well shielded, and the capacitor matching degree is high.

Description

technical field [0001] The invention relates to a capacitor unit of a high-precision capacitor array. Background technique [0002] High-precision capacitor arrays are commonly used in analog-to-digital converters (ADCs), especially successive approximation analog-to-digital converters and pipelined analog-to-digital converters. In an ADC without a capacitance calibration function, the matching degree of the capacitor array often becomes an important factor that limits the effective number of bits of the ADC and integral nonlinearity and differential nonlinearity. Especially in ADCs with 12bit resolution, the resolution is at the critical value of capacitance calibration benefits. Under this specification, the implementation of high-precision capacitor array can avoid the complexity caused by capacitance calibration. In a common design, the physical realization of the capacitor array is more biased towards the distribution of the capacitor units, and it is necessary to impr...

AI Technical Summary

Problems solved by technology

Since the metal direction of the effective side wall of the capacitor is single, and the lower plate of the capacitor is prone to parasitic with the substrate, resulting in a decrease in capacitance matching

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