CN101442325B - Amplifier with band-pass filtering function - Google Patents
Amplifier with band-pass filtering function Download PDFInfo
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- CN101442325B CN101442325B CN2007100942633A CN200710094263A CN101442325B CN 101442325 B CN101442325 B CN 101442325B CN 2007100942633 A CN2007100942633 A CN 2007100942633A CN 200710094263 A CN200710094263 A CN 200710094263A CN 101442325 B CN101442325 B CN 101442325B
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- oxide
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- variable gain
- gain amplifier
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Abstract
The invention discloses an amplifier with band-pass filtering function, which comprises a variable gain amplifier, wherein the output end of the variable gain amplifier is connected with the input end of the variable gain amplifier through a Gm-C low-pass filter, which forms a feedback loop, so that the band-pass filtering function of the variable gain amplifier is realized. The input signal and the output signal of the variable gain amplifier are both differential signal, and the structure of the variable gain amplifier comprises ten MOS tubes, so that the amplifier has the advantages of simple circuit structure, small domain area and easy realization, and can effectively eliminate the influence of DC maladjustment of the low-frequency noise.
Description
Technical field
The present invention relates to a kind of variable gain amplifier, relate in particular to a kind of amplifier with bandpass filtering function.
Background technology
Superheterodyne receiver is a kind of widely used system configuration; Its basic principle is to convert a fixed intermediate frequency signal into after passing through amplification and down-conversion to the high-frequency signal that antenna receives; Intermediate-freuqncy signal is adjusted to suitable amplitude through variable gain amplifier, extracts useful signal through bandpass filtering again and gets into demodulation.Wherein existing band pass filter circuit design is generally all comparatively complicated, is example with the Gm-C band pass filter, and is as shown in Figure 1; Its circuit structure comprises 4 Gm, is respectively: Gm1, Gm2, Gm3, Gm4, wherein; The positive input terminal of Gm4 connects positive input voltage Vinp, negative input end ground connection, the positive input terminal ground connection of Gm3; Negative input end connects negative input voltage vin n, and the output of Gm4 and Gm3 is connected at the Vout point, on the one hand through capacitor C 1 ground connection; Connect the positive input terminal of Gm1 and the output of Gm2 on the other hand respectively, the negative input of Gm1 and the positive input terminal of Gm2 be ground connection respectively, and the output of Gm1 and the negative input end of Gm2 are at V
LPThe point connection is also passed through capacitor C 2 ground connection.Though sort circuit is on the filtering performance, have very big advantage on the Q value adjustable range, its has also increased circuit area and complexity simultaneously.
Summary of the invention
Technical problem to be solved by this invention provides a kind of amplifier with bandpass filtering function; It can be through adopting simple Gm-C low-pass-filter feedback loop; Make VGA (variable gain amplifier) output signal and input signal subtract each other the realization high pass characteristic; Again because the low-pass characteristic of VGA self, the amplifier of having realized having the bandpass filtering function.
In order to solve above technical problem; The invention provides a kind of amplifier with bandpass filtering function, comprise a variable gain amplifier, its output is connected to its input through a Gm-C low pass filter; Form feedback control loop, realize the bandpass filtering function of variable gain amplifier.
Because the present invention uses above-mentioned circuit structure, it is simple to have form, and chip area is little, and characteristics such as easy realization have effectively been eliminated the influence of low-frequency noise and DC maladjustment.
Description of drawings
Below in conjunction with accompanying drawing and embodiment the present invention is done further explain.
Fig. 1 is existing band pass filter circuit;
Fig. 2 is the circuit structure with amplifier of bandpass filtering function of the present invention;
Fig. 3 is the circuit structure of variable gain amplifier of the present invention.
Embodiment
As shown in Figure 2; Be the circuit structure with amplifier of bandpass filtering function of the present invention, comprise a variable gain amplifier VGA, its output is connected to its input through a Gm-C low pass filter; Form feedback control loop, realize the bandpass filtering function of variable gain amplifier.Wherein the input signal VIN of variable gain amplifier is differential signal with output signal VOUT.
Fig. 3 is the circuit structure of variable gain amplifier VGA of the present invention; Comprise ten metal-oxide-semiconductors, metal-oxide-semiconductor M1 and M2 are for importing pipe, and its grid end connects positive and negative differential input signal respectively; Its source end links together through current source metal-oxide-semiconductor M5 ground connection; Its drain terminal is connected to power supply through load metal-oxide-semiconductor M0 and M6 respectively, and metal-oxide-semiconductor M3 and M4 import pipe for feedback, and its grid end connects positive and negative feedback differential input signal respectively; Its source end links to each other with the source end of metal-oxide-semiconductor M1 and M2 respectively; The drain terminal of metal-oxide-semiconductor M4 is connected to the drain terminal of metal-oxide-semiconductor M1, and the drain terminal of metal-oxide-semiconductor M3 is connected to the drain terminal of metal-oxide-semiconductor M2, and metal-oxide-semiconductor M8 and M9 connect into the drain terminal sampling that the diode mode is connected to metal-oxide-semiconductor M1 and M2 respectively; And coming the grid end of control load metal-oxide-semiconductor M0 and M6 through common-mode feedback, the source end of metal-oxide-semiconductor M8 and M9 links together and is connected to ground through current source metal-oxide-semiconductor M7.
As shown in Figure 3; Vinp and Vinn are the voltage of intermediate frequency signal that radio-frequency front-end is sent here in the foregoing circuit; The differential pair of forming through M1 and M2 converts current signal into, and the voltage signal Vfbn and the Vfbp that send here by the Gm-C low-pass-filter feedback loop, also the differential pair through M3 and M4 composition converts current signal into; This two-way current signal subtracts each other at output node Vp and Vn, and is converted into voltage signal through the active load of M0 and M6.Because the signal that Vfbn and Vfbp send here is Vinp and the signal of Vinn behind LPF, this two paths of signals subtracts each other can realize the high-pass filtering characteristic, filtering the interference of low-frequency noise and DC maladjustment.And Vc+ that gain control circuit is sent here and Vc-signal convert electric current into through the differential pair of M5 and M7 composition, are controlling the size of current that flows through M1 ~ M4, thereby can control this Amplifier Gain.Because the low-pass characteristic of VGA self, what this structure realized at last is a variable gain amplifier with bandpass filter function.
Claims (1)
1. amplifier with bandpass filtering function; It is characterized in that, comprise a variable gain amplifier, its output is connected to its input through a Gm-C low pass filter, forms feedback control loop, realizes the bandpass filtering function of said variable gain amplifier; The input signal of said variable gain amplifier is differential signal with the output signal; Described variable gain amplifier structure comprises ten metal-oxide-semiconductors, and metal-oxide-semiconductor M1 and M2 are for importing pipe, and its grid end connects positive and negative differential input signal respectively; Its source end links together through current source metal-oxide-semiconductor M5 ground connection; Its drain terminal is connected to power supply through load metal-oxide-semiconductor M0 and M6 respectively, and metal-oxide-semiconductor M3 and M4 import pipe for feedback, and its grid end connects positive and negative feedback differential input signal respectively; Its source end links to each other with the source end of metal-oxide-semiconductor M1 and M2 respectively; The drain terminal of metal-oxide-semiconductor M4 is connected to the drain terminal of metal-oxide-semiconductor M1, and the drain terminal of metal-oxide-semiconductor M3 is connected to the drain terminal of metal-oxide-semiconductor M2, and metal-oxide-semiconductor M8 and M9 connect into the drain terminal sampling that the diode mode is connected to metal-oxide-semiconductor M1 and M2 respectively; And coming the grid end of control load metal-oxide-semiconductor M0 and M6 through common-mode feedback, the source end of said metal-oxide-semiconductor M8 and M9 links together and is connected to ground through current source metal-oxide-semiconductor M7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2007100942633A CN101442325B (en) | 2007-11-22 | 2007-11-22 | Amplifier with band-pass filtering function |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2007100942633A CN101442325B (en) | 2007-11-22 | 2007-11-22 | Amplifier with band-pass filtering function |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101442325A CN101442325A (en) | 2009-05-27 |
| CN101442325B true CN101442325B (en) | 2012-07-11 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN2007100942633A Active CN101442325B (en) | 2007-11-22 | 2007-11-22 | Amplifier with band-pass filtering function |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105897205B (en) * | 2016-04-06 | 2018-08-07 | 江苏星宇芯联电子科技有限公司 | A kind of variable gain instrument amplifier of low-pass filtering |
| US9973160B2 (en) * | 2016-10-17 | 2018-05-15 | Realtek Semiconductor Corp. | Amplifier device |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1369963A (en) * | 2001-02-14 | 2002-09-18 | 矽统科技股份有限公司 | DC drift eliminator for grain-variable amplifier |
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2007
- 2007-11-22 CN CN2007100942633A patent/CN101442325B/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1369963A (en) * | 2001-02-14 | 2002-09-18 | 矽统科技股份有限公司 | DC drift eliminator for grain-variable amplifier |
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| CN101442325A (en) | 2009-05-27 |
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Owner name: SHANGHAI HUAHONG GRACE SEMICONDUCTOR MANUFACTURING Free format text: FORMER OWNER: HUAHONG NEC ELECTRONICS CO LTD, SHANGHAI Effective date: 20131216 |
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Free format text: CORRECT: ADDRESS; FROM: 201206 PUDONG NEW AREA, SHANGHAI TO: 201203 PUDONG NEW AREA, SHANGHAI |
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Effective date of registration: 20131216 Address after: 201203 Shanghai city Zuchongzhi road Pudong New Area Zhangjiang hi tech Park No. 1399 Patentee after: Shanghai Huahong Grace Semiconductor Manufacturing Corporation Address before: 201206, Shanghai, Pudong New Area, Sichuan Road, No. 1188 Bridge Patentee before: Shanghai Huahong NEC Electronics Co., Ltd. |