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Low-noise, high-bandwidth tunnel current preamplifier circuit

A technology of preamplification circuit and tunnel current, which is applied in the field of scanning tunneling microscope, can solve the problems that cannot meet the high dynamic measurement requirements, and achieve the effect of increasing bandwidth and reducing noise

Inactive Publication Date: 2012-10-17
ZHEJIANG UNIV
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Problems solved by technology

However, the traditional tunnel current preamplifier circuit used in scanning tunneling microscopes is generally composed of a single-stage or two-stage negative feedback transimpedance amplifier circuit. The bandwidth of the circuit is affected by the parasitic capacitance of the reference resistor. The bandwidth is generally below 1KHz, which cannot meet high Dynamic Measurement Requirements

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  • Low-noise, high-bandwidth tunnel current preamplifier circuit

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Embodiment Construction

[0012] Below in conjunction with accompanying drawing, this patent is further described.

[0013] Such as figure 1 As shown, the low-noise and high-bandwidth tunnel current preamplifier circuit is connected between the probe and the follow-up control circuit. It consists of two stages of amplification units. The first stage of amplification unit is used to reduce signal noise; Increase signal bandwidth;

[0014] The first-stage amplifying unit is a transimpedance amplifying circuit, which includes a first amplifier A1, a first resistor R1, and a first capacitor C1, wherein one end of the first resistor R1 and one end of the first capacitor C1 are connected to the probe, The other end of the first resistor R1 and the other end of the first capacitor C1 are connected to the output end of the first amplifier A1, the inverting input end of the first amplifier A1 is connected to the probe, and the non-inverting input end of the first amplifier A1 is grounded;

[0015] The second-...

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Abstract

The invention discloses a low-noise, high-bandwidth tunnel current preamplifier circuit. The low-noise, high-bandwidth tunnel current preamplifier circuit is connected between a probe and a subsequent control circuit, and comprises two stages of amplifier units; the first stage of amplifier unit is used for decreasing signal noise; the second stage of amplifier unit is used for increasing signal bandwidth; the first stage of amplifier unit is a transimpedance amplifier circuit, which comprises a first amplifier, a first resistor and a first capacitor; and the second stage of amplifier unit is a push-pull amplifier circuit, which comprises a second amplifier, a third amplifier, a second capacitor, a second resistor, a third capacitor, a third resistor, a fourth capacitor, a fourth resistor and an adjustable resistor. Since the low-noise, high-bandwidth tunnel current preamplifier circuit comprises the first stage of transimpedance amplifier circuit and the second stage of push-pull amplifier circuit, the introduction of the push-pull amplifier circuit greatly increases the bandwidth of tunnel current signal detection. Moreover, the joint end of the circuit and the probe is insulated by a teflon insulating column and suspended to be soldered, and therefore is not in contact with a circuit board, consequently, the noise of signal detection is greatly reduced, and while the bandwidth is increased, the precision of tunnel current signals is increased.

Description

technical field [0001] The invention relates to the field of scanning tunneling microscopes, in particular to a tunnel current preamplifier circuit with low noise and high bandwidth. Background technique [0002] Scanning Tunneling Microscopy (STM) mainly utilizes the quantum tunneling effect caused by the nano-space between needle-tip samples, and the tunnel current is exponentially related to the space to realize the local detection of the sample, thus achieving the microstructure of the surface of the new material. Atomic resolution. Tunneling current is an exponential function of pitch. If the tip-sample gap changes by 10%, the tunneling current changes by an order of magnitude. This exponential relationship gives the STM a high sensitivity. The two working modes of the STM need to be based on the high-speed and high-precision detection of the tunnel current: in the constant-height mode, the needle tip runs on a horizontal plane above the sample, and the tunnel current...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01Q60/10H03F1/42
Inventor 居冰峰陈远流张威朱吴乐姜燕
Owner ZHEJIANG UNIV
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