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High-speed low-noise scanning tunnel microscope pre-amplification circuit

A pre-amplifier circuit and scanning tunnel technology, which is applied in the field of high-speed and low-noise scanning tunneling microscope pre-amplifier circuits, can solve the problems of unusable performance and difficulty in normal use of UNC-OPA, and achieve the effect of high signal-to-noise ratio.

Pending Publication Date: 2019-05-24
HENAN NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Or some circuits only need to be amplified by a small multiple, and the UNC-OPA with superior performance cannot be used
[0007] In order to solve the dilemma that the above-mentioned UNC-OPA is difficult to be used normally, the present invention designs a scanning tunneling microscope preamplifier based on an incompletely compensated operational amplifier.

Method used

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  • High-speed low-noise scanning tunnel microscope pre-amplification circuit
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  • High-speed low-noise scanning tunnel microscope pre-amplification circuit

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] as attached figure 1 As shown, the method of using UNC-OPA is: first, select the feedback resistor R of the scanning tunneling microscope preamplifier circuit F The resistance value, such as 1GOhm; secondly, set the noise gain (1+R f / R 0 ) is greater than or equal to the minimum noise gain G of the amplifier circuit containing the UNC-OPA Nmin =5, that is, R 0 =250MOhm; Finally, carry out STM test, which can achieve higher signal-to-noise ratio and speed.

[0023] In the specific STM test, select the appropriate feedback resistor R f and R 0 value, we finally got a line speed of more than 10,000 lines per second and a frame rate of more than 100 pictures per second, realizing the atomic resolution image of the world's highest speed STM, the sample is highly ordered graphite (HOPG), as attached figure 2 shown. This amplifying circuit will have extremely high bandwidth and signal-to-noise ratio.

Embodiment 2

[0025] as attached image 3 shown, the resistor R 0 It can be replaced by a potentiometer R with adjustable resistance. Because the noise gain of the amplifying circuit including UNC-OPA is (1+R f / R), when R changes, its noise gain also changes accordingly, so we can change the gain of the amplifier circuit containing UNC-OPA by adjusting the potentiometer R, so as to find the The minimum gain of the amplifier circuit.

Embodiment 3

[0027] as attached Figure 4 shown, the R 0 A switch is connected in series on the branch. When the STM collects the sample information, the probe will gradually approach the sample. In the case of coarse approximation, the equivalent resistance value of the probe-sample junction tends to infinity, and the noise gain of the STM preamplifier is almost 1. When approached to a certain extent, the probe-sample equivalent resistance is no longer infinite, but reaches a value that is small enough and cannot be ignored. At this time, do not connect a resistor R in parallel across the probe-sample junction 0 , can also meet the minimum gain requirement of the amplifying circuit including UNC-OPA. Therefore, the resistor R can be removed at this time 0 , without affecting the stability of the STM preamplifier circuit. At the same time, because R 0 There is unavoidable thermal noise, so when detecting extremely weak signals, which are weak enough to match the intensity of thermal...

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Abstract

The invention discloses a high-speed low-noise scanning tunnel microscope pre-amplification circuit. The circuit comprises a non-complete compensation operational amplifier UNC-OPA, Probe-sample junction, Feedback resistor RF, a bias voltage UB and a resistor R0, wherein one end of the probe-sample junction is connected with the inverting input end of the incomplete compensation operational amplifier; wherein the other end of the probe-sample junction is grounded, the resistor R0 is connected in parallel with two ends of the probe-sample junction, a feedback resistor RF is connected between the inverting input end and the output end of the incomplete compensation operational amplifier, the in-phase input end of the incomplete compensation operational amplifier is connected with the positive electrode of the bias voltage UB, and the negative electrode of the bias voltage UB is grounded. The amplifier circuit with any gain can use the UNC-OPA, and high-speed and high-signal-to-noise-ratio output is realized.

Description

technical field [0001] The invention belongs to the technical field of incompletely compensated operational amplifiers, in particular to a high-speed and low-noise scanning tunneling microscope preamplifier circuit. Background technique [0002] The uncompensated operational amplifier (uncompensated operational amplifier, referred to as UNC-OPA) has almost all the advantages of high speed, low noise and more ideal op amp. Its only disadvantage is non-unity-gain-stable (UGS for short), that is, only when its noise gain reaches a certain minimum noise gain, can it amplify the signal stably. [0003] Due to the background of current STM technology, the equivalent resistance value of the probe-sample junction tends to infinity when STM is roughly approximated, and the noise gain is almost 1. This situation makes only unity-gain stable operational amplifiers can be applied to STM put forward. [0004] The probe-sample junction parallel resistance method mentioned in the patent ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03F1/26H03F3/45H03G3/34G01Q60/10
Inventor 李全锋郑文静吴黎明
Owner HENAN NORMAL UNIV
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