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A 12-Bit Voltage DAC Based on Dual 8-Bit Resistive Divider DACs | IEEE Conference Publication | IEEE Xplore

A 12-Bit Voltage DAC Based on Dual 8-Bit Resistive Divider DACs


Abstract:

A 12-bit voltage digital-to-analog converter (DAC) based on a dual 8-bit resistive divider DACs is proposed. The resistor ladder structure is used to achieve two 8-bit DA...Show More

Abstract:

A 12-bit voltage digital-to-analog converter (DAC) based on a dual 8-bit resistive divider DACs is proposed. The resistor ladder structure is used to achieve two 8-bit DACs. Then, analog addition, subtraction, multiplication, and division operations are performed on the outputs of the two 8-bit DACs, achieving a final 12-bit DAC output voltage. The circuit structure is simple, it only uses a total of 512 resistors, avoiding the problem of requiring a larger area and being susceptible to process mismatch as in traditional structures that use 4096 resistors. The proposed 12-bit voltage DAC is designed using HHGRACE 110nm process, and the entire area is 0.144\ \text{mm}^{2}. The post-simulation results show that, under typical process and temperature conditions, the simulated DNL is −0.17~0.13 LSB, INL is −0.06~0.23 LSB, SFDR is 87.7734 dB, and ENOB is 11.8604 bits.
Date of Conference: 27-30 October 2023
Date Added to IEEE Xplore: 29 December 2023
ISBN Information:
Conference Location: Huzhou, China

Funding Agency:


I. Introduction

With the rapid development of electronic medical devices, aerospace, automotive, and radar fields, the demand for high-precision DACs is also rising. For example, in control fields such as radar systems, the accuracy and linearity of DACs directly affect the performance indicators of the system [1], requiring the design of high-precision and high-linearity DACs. There are mainly charge-redistribution type, current steering type, and resistor divide type structures for DACs. Charge-redistribution DACs have higher resolution but poor monotonicity. They require high matching accuracy of capacitors in the circuit and often occupy a large chip area [2]. Therefore, it is rarely considered to achieve a resolution above 12 bits using charge-redistribution DACs. The structures suitable for high-precision and high-linearity DACs are mainly resistive divider type and current steering type. When the accuracy of the current steering DAC exceeds 10 bits, the units current source control switch regularly adopts a segmented decoding structure. Usually, the Most Significant Bits (MSB) use thermometer decoding, and the Least Significant Bits (LSB) use binary-weighted decoding. However, in this way, the current steering type DACs may produce large glitches in certain specific input codes, such as transitioning from all 1 to all 0 for low bits and carrying over to the high-order bits, which introduces the risk of code error [3]. Resistive divider DACs have the advantages of a simple structure and good linearity. However, in standard CMOS processes, most resistive divider DACs can only achieve an accuracy of 8–9 bits [4]. This is mainly because the accuracy is primarily limited by the matching of the resistors. As the resolution of the DAC increases, the number of resistors needs to increase exponentially, and the impact of mismatch in the resistor string will be greater.

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References

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