A Pixel Unit Circuit Based on Correlated Double Sampling and Its Correlated Double Sampling Method

Abstract

The invention discloses a pixel unit circuit based on correlated double sampling and a correlated double sampling method thereof, belonging to the technical field of integrated circuits. The pixel unit circuit includes: an integrating circuit, a correlated double sampling circuit and a source follower circuit; the correlated double sampling circuit comprises a sampling switch, a first capacitor, a second capacitor and a first reset switch; the output terminal of the integrating circuit is connected to the sampling switch The input end is connected, the output end of the sampling switch is respectively connected with one end of the first capacitor and one end of the second capacitor, the other end of the first capacitor is grounded, and the other end of the second capacitor is respectively connected with the output end of the first reset switch and the source follower The input terminal of the switch circuit is connected, and the input terminal of the first reset switch is connected with the first reset voltage. The unit pixel circuit in the present invention has a simple overall structure, and the correlated double sampling circuit not only effectively suppresses the KTC noise of the integral capacitance and the 1 / f noise of the integral operational amplifier, improves the signal-to-noise ratio, but also has easy operation of timing control.

Description

technical field [0001] The invention relates to the technical field of integrated circuits, in particular to a pixel unit circuit based on correlated double sampling and a correlated double sampling method thereof. Background technique [0002] With the development of science and technology, infrared imaging technology is becoming more and more mature. Thanks to its good concealment, long range, no electromagnetic interference, and strong detection ability, it is widely used in national defense, scientific research, civil, industrial and other related fields. Applications. The core component of the infrared imaging system is the infrared focal plane detector assembly, which consists of two parts: the infrared detector assembly and the infrared focal plane readout circuit; the infrared signal is collected through the infrared detector assembly, and then the signal is realized by the infrared focal plane readout circuit. conversion, and finally the obtained original image is ...

AI Technical Summary

Problems solved by technology

In the pixel unit circuit, since the infrared detector outputs a weak current, usually in the order of nanoampere or even picoampere, in order to obtain a larger output voltage, the integrating capacitor in the pixel unit circuit needs to be very small, and this It will inevitably lead to the introduction of large KTC noise due to the on-off of the reset switch of the integrating circuit, plus the thermal noise and 1 / f noise of the integrating operational amplifier, etc., these noises will have a great impact on the performance of the pixel unit circuit; And the initial value of the output voltage of the traditional pixel unit circuit is determined by the bias voltage V of the integral operational amplifier cm It is determined that for an integral operational amplifier with a small swing, when the integral time is too long, the integral voltage no longer increases linearly, but increases slowly, and then approaches a voltage value, so it is also very useful to be able to freely set the initial value of the output voltage necessary

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