Asynchronous successive approximation analog-to-digital converter and conversion method

Abstract

The invention discloses an asynchronous successive approximation analog-to-digital converter and a conversion method. The asynchronous successive approximation analog-to-digital converter comprises: a sampling network, a main capacitor array, an auxiliary capacitor array, a comparator and a logic control circuit. The sampling network of the main capacitor array uses a bootstrap switch. The sampling network of the auxiliary capacitor array uses a CMOS switch. Each two same capacitors in the main capacitor array are in a group. A capacitance value size is reduced as two times relationship. Top crowns of all the capacitors and the bootstrap switch are connected and output to the comparator. The each two same capacitors in the auxiliary capacitor array are in one group. The capacitance value size is reduced as four times relationship. The top crowns of all the capacitors and the CMOS switch are connected and output to the comparator. The comparator comprises a preamplifier and a latch and compares the size of an output voltage of the main capacitor array and the auxiliary capacitor array. The logic control circuit uses an asynchronous sequential control capacitor array to successively complete switching. A power consumption efficiency of the analog-to-digital converter can be effectively raised. And demands of capacitor coupling and a peripheral circuit can be reduced. The method is suitable for a deep-submicron low voltage design.

Description

technical field [0001] The present invention relates to an asynchronous successive approximation analog-to-digital converter and a conversion method, in particular to an asynchronous successive approximation converter which improves power consumption efficiency, reduces capacitance matching and peripheral circuit requirements by improving the retrieval method, and is suitable for deep submicron low power supply voltage. approximation to the analog-to-digital converter. technical background [0002] The successive approximation analog-to-digital converter is a type used in medium precision and medium sampling rate. Compared with other types of analog-to-digital converters such as flash type and pipeline type, it has the highest power consumption efficiency. It is widely used in medical and portable equipment. Applications. [0003] The traditional synchronous successive approximation analog-to-digital converter requires a high-speed system clock (sampling frequency times the...

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Problems solved by technology

[0003] The traditional synchronous successive approximation analog-to-digital converter requires a high-speed system clock (sampling frequency times the number of converter resolution digits), whether it is generated internally or directly input from off-chip will increase the extra power consumption of the chip, so that the successive approximation The high power efficiency of the

[0004] Since the successive approximation ADC requires an array of capacitors in increments of two, the matching between the minimum and maximum capacitors limits the overall accuracy of the ADC

The use of unit capacitance and centrosymmetric layout can reduce the impact of this limitation, but it cannot fundamentally solve this problem. Many designs use digital correction to improve the accuracy of capacitance matching.

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