Successive approximation type analog-to-digital converter using unit bridge capacitor and quantization method of successive approximation type analog-to-digital converter

Abstract

The invention discloses a successive approximation analog-to-digital converter using unit bridge capacitors and a quantization method thereof, the analog-to-digital converter comprises a DAC segmented capacitor array and two operational amplifiers, the N-bit DAC segmented capacitor array is divided into M high-bit binary quantization capacitors and N-M low-bit binary quantization capacitors through bridge capacitors, the low-order capacitor array further comprises a redundant capacitor and is connected to the high-order capacitor array through a unit negative feedback operational amplifier and a bridge capacitor. Compared with a traditional sectional type capacitor array, the bridge capacitor is the same as the lowest-order capacitor in size, fractional capacitors are avoided, and the matching precision of the capacitor array is improved; in addition, the design requirement of an internal operational amplifier of the DAC is lowered through reasonable sequential control, and compared with a traditional SAR ADC architecture adopting a sectional capacitor array DAC, the SAR ADC architecture has the advantage of being high in capacitor matching precision.

Description

technical field [0001] The invention belongs to the technical field of integrated circuits, and in particular relates to a successive approximation analog-to-digital converter using unit bridge capacitance and a quantization method thereof. Background technique [0002] As a bridge connecting real-world analog signals and system internal signals, analog-to-digital converters (ADCs) are widely used in multimedia, communication, biomedical, and sensor control fields. [0003] In recent years, with the further development of deep submicron technology, SAR ADC (Successive Approximation Analog-to-Digital Converter) has gradually gained the widest application in medium-to-high-precision, medium-to-high-speed occasions. There are also many implementation methods for SAR ADC. Among them, the structure based on capacitive charge redistribution was first proposed by James L.McCreary of the University of California, Berkeley. It can achieve relatively small power consumption and is ver...

AI Technical Summary

Problems solved by technology

[0006] In order to ensure that the sum of all the capacitors of the low-order array and the capacitance value obtained after being connected in series with the bridge capacitor is equal to the value of the lowest-order capacitor of the high-order array, the bridge capacitor needs to take a fractional value of the unit capacitance value. In the layout design of integrated circuits, it is generally designed first A good unit capacitor, and then multiple unit capacitors in parallel to achieve double the unit capacitance value, four times the unit capacitance value and other effects; and the fractional capacitance value obviously cannot be achieved in this way, so the fractional capacitance value of the bridge capacitor is difficult to achieve Match the unit capacitance value, that is, the capacitance value of the bridge capacitor is prone to errors

Since the bridge capacitor is connected in series with the entire low-level capacitor array, according to the capacitor series formula, the mismatch of the bridge capacitor will cause a large deviation when the low-level capacitor array is equivalent to the high-level capacitor array, resulting in the failure of the low-level capacitor array, resulting in a sharp drop in ADC performance. decline

[0007] The segmented capacitor array connected by bridge capacitors can solve the problem of too large layout area of ​​the capacitor array, but at the same time, because the bridge capacitor must be designed as a fractional value, it is difficult to achieve in the layout design of the integrated circuit, and the process deviation is large, which will affect the final ADC. The conversion accuracy has a large impact

Images