Mean voltage generating circuit and method for providing reference voltage for pixel array

Abstract

The invention relates to the field of integrated circuits, and provides an average reference voltage generation circuit for improving detectability to external light intensity, particularly weak light and strong light, on the basis of PWM (pulse width modulation) digital pixels, that is, improving the dynamic range, so as to realize a PWM pixel array structure of which Vref can automatically adapt to the external light intensity. The invention adopts the technical scheme that the average voltage generation circuit for providing reference voltage for the pixel array is structurally characterized in that a PWM pixel array is divided into groups, and each group comprises N adjacent pixels; each group of pixels forms a working unit together with an AVG (average Vref generator), each VPD node in the unit is connected to N input ends (in 1-in N) of the AVG, and the input end of each reference voltage is connected to the output end (Vout) of the AVG; the AVG comprises N input switches (S 1-S N), one sampling capacitor CH, one amplifier AMP and one n-bit memorizer. The average voltage generation circuit and the average voltage generation method are mainly applied to the design of the integrated circuit.

Description

technical field [0001] The present invention relates to the field of integrated circuits, in particular to a pixel array architecture based on the PWM principle, and in particular to an average voltage generating circuit for providing a dynamic reference voltage for a PWM pixel array. technical background [0002] The light detection of CMOS (Complementary Metal Oxide Semiconductor, Complementary Metal Oxide Semiconductor) image sensor can be realized by way of PWM (Pulse Width Modulation, pulse width modulation), refer to figure 1 , the PWM-based pixel structure and working process are as follows: a typical PWM pixel consists of a PD (Photo Diode, photodiode), a reset transistor M RST , pixel level, column level comparator and pixel level, column level or array level memory ( figure 1 Take pixel-level comparator and pixel-level memory as an example). The input terminals of the pixel-level comparator are respectively the PD node voltage and the set reference voltage V ref...

AI Technical Summary

Problems solved by technology

In summary, the classic PWM pixel structure requires higher and lower V ref , to shorten or lengthen t sig can be detected by subsequent circuits, so the fixed V in this type of PWM pixel ref The value is often not suitable for the current lighting environment, resulting in a small DR

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