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Integrated operational amplifying circuit capable of increasing bandwidth to short-wave frequency band and reducing noise

A technology for integrating operational amplifiers and amplifier circuits, applied in the field of high-bandwidth preamplifier circuits, can solve the problems of large feedback resistors that are difficult to achieve high bandwidth, and achieve the effects of simple structure, increased bandwidth, and reduced noise

Inactive Publication Date: 2015-09-02
HENAN NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The technical problem solved by the present invention is to provide an integrated op-amp amplifying circuit that increases the bandwidth to the short-wave frequency band and reduces noise. The technical scheme of the amplifying circuit overcomes the The large feedback resistance is difficult to achieve high bandwidth and high bandwidth will inevitably bring high noise problems, while achieving the ideal effect of high bandwidth and low noise

Method used

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  • Integrated operational amplifying circuit capable of increasing bandwidth to short-wave frequency band and reducing noise
  • Integrated operational amplifying circuit capable of increasing bandwidth to short-wave frequency band and reducing noise
  • Integrated operational amplifying circuit capable of increasing bandwidth to short-wave frequency band and reducing noise

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Embodiment 1

[0030] The selected integrated operational amplifier is the integrated operational amplifier of Texas Instruments (TI) company in the United States, whose model is OPA627BP, and its nominal value of gain-bandwidth product is 16MHz. Input resistance R in =2MW, feedback resistance R f =10MW. (R in with R f The values ​​are all within the resistance selection range of STM 1M-1GW). by Theory R in 'C in =R f 'C f Calculated: the input capacitor needs to be 5 times the feedback capacitor, that is, C in =5C f . In order to reduce the influence of parasitic capacitance which is difficult to measure, the input capacitance C is selected here in =100pF, feedback capacitance C f =20pF, the data analysis is as follows:

[0031] Without input capacitor C in =100pF and the feedback capacitance C f =20pF, input resistance R in and the feedback resistor R f There is a parallel parasitic capacitance of less than 1pF at both ends, the bandwidth obtained by the test is less than ...

Embodiment 2

[0038] (1) Without input capacitor C in =100pF and the feedback capacitance C f =20pF, input resistance R in and the feedback resistor R f When there is only less than 1pF of parasitic capacitance between the upper and lower ends, the tested bandwidth is less than 150kHz, and the frequency response in the bandwidth area is extremely uneven.

[0039] (2) Add the input capacitor C in =100pF and the feedback capacitance C f After =20pF, the bandwidth reaches 4.1MHz, and the frequency response in the bandwidth area is relatively flat, as shown in the attached Figure 4 shown. Only due to the limitation of the gain-bandwidth product of the integrated operational amplifier itself, the gain slowly decreases. If you choose an integrated operational amplifier with a larger gain-bandwidth product (GBPW) and more accurately satisfy the relationship R in 'C in =R f 'C f , or reduce the gain, the bandwidth will be higher.

[0040] This example applies C in =100pF and the feedbac...

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Abstract

The invention discloses an integrated operational amplifying circuit capable of increasing the bandwidth to the short-wave frequency band and reducing noise and belongs to the technical field of high-bandwidth and low-noise front amplifying circuits. The technical scheme is as follows: the circuit is characterized in that an input resistor Rin and an input capacitor Cin which are connected in parallel are arranged between a negative signal input end Vin- and an inverting input end V- of an integrated operational amplifier OPA, the negative signal input end Vin- is connected with an input signal, a feedback resistor Rf and a feedback capacitor Cf which are connected in parallel are arranged between the inverting input end V- of the integrated operational amplifier OPA and a signal output end Vout of the integrated operational amplifier OPA, a non-inverting input end V+ of the integrated operational amplifier OPA is grounded through a positive signal input end Vin+ or connected with reference potential. On the premise that the used integrated operational amplifying gain bandwidth product effect is not considered, if Rin'Cin is equal to Rf'Cf, the bandwidth of the amplifying circuit is infinite. The circuit is simple in structure and reasonable in design, can realize double effects of increasing the bandwidth and reducing the noise simultaneously, and has the broader application prospect.

Description

Technical field: [0001] The invention belongs to the technical field of high-bandwidth preamplifier circuits, and in particular relates to an integrated op-amp amplifier circuit that increases the bandwidth to the short-wave frequency band and reduces noise. Background technique [0002] At present, with the rapid development of high-speed and high-precision nanotechnology, the importance of high-bandwidth and low-noise preamplifier circuits has become increasingly prominent, such as in the development of high-speed imaging scanning tunneling microscopes (STM). However, the current high-bandwidth preamplifier circuits have the following problems: (1) When the high-bandwidth circuit amplifies the useful signal, it will inevitably amplify the noise in the frequency band, resulting in a decrease in the signal-to-noise ratio. It is difficult to be compatible with low noise, and usually has to choose a compromise between high bandwidth and low noise; (2) The feedback resistance o...

Claims

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Application Information

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IPC IPC(8): H03F1/26H03F1/42H03F3/45
Inventor 李全锋王凯涛张宗哲
Owner HENAN NORMAL UNIV