CN102158193B - Second-order band-pass filter based on negative feedback - Google Patents

Abstract

The invention relates to a second-order band-pass filter based on negative feedback, belonging to the design field of analog filters. The second-order band-pass filter based on negative feedback is implemented by PMOS (P-channel Metal Oxide Semiconductor) tubes or NMOS (N-channel Metal Oxide Semiconductor) tubes, and comprises a first NMOS (N-channel Metal Oxide Semiconductor) tube M3l, a second NMOS (N-channel Metal Oxide Semiconductor) tube M3r, a third NMOS (N-channel Metal Oxide Semiconductor) tube M2l, a fourth NMOS (N-channel Metal Oxide Semiconductor) tube M2r, a fifth NMOS (N-channel Metal Oxide Semiconductor) tube M1l, a sixth NMOS (N-channel Metal Oxide Semiconductor) tube M1r, a first capacitor C11, a second capacitor C21, a third capacitor C2r, a fourth capacitor C1r, a first current source Ib1 and a second current source Ib2. The invention is based on negative feedback process, does not need a common mode feedback circuit, and effectively reduces the power consumption; only eight transistors are used for implementing a double second-order unit, and the four-order band-pass filter can be implemented by only sixteen transistors; the second-order band-pass filter based on negative feedback process is symmetrical in structure and easy to design and effectively reduces the complexness of the band-pass filter structure; the band-pass gain can be adjusted via transconductance proportions of a first PMOS (P-channel Metal Oxide Semiconductor) tube to a second PMOS (P-channel Metal Oxide Semiconductor) tube, and a fifth PMOS (P-channel Metal Oxide Semiconductor) tube to a sixth PMOS (P-channel Metal Oxide Semiconductor) tube.

Description

A kind of based on degenerative second-order bandpass filter

Technical field

The invention belongs to the analog filter technical field, particularly a kind of based on degenerative second-order bandpass filter.

Background technology

Usually, second-order bandpass filter (the logical double-two-order unit of band) transfer function is as follows:

$H\left(s\right)=\frac{K\frac{{\mathrm{\ω}}_0}{Q_0}s}{s^2+\frac{{\mathrm{\ω}}_0}{Q_0}s+{\mathrm{\ω}}_0^2}---\left(1\right)$

In the formula (1) as can be known second-order bandpass filter plural limit will be arranged, therefore require will to have in the transistor level double-two-order unit can comprehensive plural limit circuit structure.

In actual applications, the demand to higher order filter is more.Usually second-order bandpass filter is mainly used in adopting in the cascade method design high-order low-pass filter.About the cascade method and the inductance method of substitution design higher order filter relevant knowledge of active filter can be with reference to Deliyannis, T., Sun, Y., and Fidler, J., K.: ' Continuous-Time Active Filter Design ' Boca Raton, FL:CRC, 1999.

Will realize frequency-selecting at traditional superheterodyne receiver by the one-level band pass filter after the frequency conversion first time, adopt the outer Surface Acoustic Wave Filter (SAW filter) of sheet usually, hardware costs is very big.At present integrated circuit fully integrated (System on Chip) direction on the sheet develops, and replaces the outer Surface Acoustic Wave Filter of sheet by fully integrated band pass filter on the sheet.Le-Thai is at list of references " Ha Le-Thai, Huy-Hieu Nguyen, Hoai-Nam Nguyen, Hong-Soon Cho, Jeong-Seon Lee, and Sang-Gug Lee, " An IF Bandpass Filter Based on a Low Distortion Transconductor; " IEEE Journal of Solid-State Circuits, pp.2250-2261, Nov.2010 " in a kind of fourth-order band-pass filter has been described, form by seven transconductance cell altogether, and each transconductance cell as shown in Figure 1, comprises the main circuit that 16 transistors are formed, the symmetrical negative impedance circuit of the counteracting main circuit output node impedance of 4 transistor compositions and 8 common mode feedback circuits that transistor is formed.The subject matter that exists is: (1) needs common mode feedback circuit; (2) more than the number of transistors, the circuit complexity.

Summary of the invention

The objective of the invention is for overcoming the weak point of prior art, propose a kind ofly, can under the situation that does not increase common mode feedback circuit, effectively reduce the power consumption of filter cell based on degenerative second-order bandpass filter.

For achieving the above object, the invention provides a kind of degenerative second-order bandpass filter, it is characterized in that, adopt the PMOS pipe to realize, this second-order bandpass filter comprises PMOS pipe M _3l, the 2nd PMOS manages M _3r, the 3rd PMOS manages M _2l, the 4th PMOS manages M _2r, the 5th PMOS manages M _1l, the 6th PMOS manages M _1r, first capacitor C _1l, second capacitor C _2l, the 3rd capacitor C _2r, the 4th capacitor C _1r, the first current source I _B1With the second current source I _B2Wherein, PMOS pipe M _3lDrain electrode meet the negative terminal V of output node _Op, a PMOS manages M _3lGrid connect the input node anode V _Ip, a PMOS manages M _3lSource electrode meet supply voltage VDD; The 2nd PMOS manages M _3rDrain electrode meet the anode V of output node _Op, the 2nd PMOS manages M _3rGrid connect the input node negative terminal V _In, the 2nd PMOS manages M _3rSource electrode meet supply voltage VDD; The 3rd PMOS manages M _2lGrid meet the negative terminal V of output node _On, the 3rd PMOS manages M _2lSource electrode meet supply voltage VDD; The 4th PMOS manages M _2rGrid meet the anode V of output node _Op, the 4th PMOS manages M _2rSource electrode meet supply voltage VDD; The 5th PMOS manages M _1lGrounded drain voltage GND, the 5th PMOS manages M _1lSource electrode meet the negative terminal V of output node _OnThe 6th PMOS manages M _1rGrounded drain voltage GND, the 6th PMOS manages M _1rSource electrode meet the anode V of output node _OpFirst capacitor C _1lMinus earth voltage GND; Second capacitor C _2lPositive pole meet the negative terminal V of output node _On, second capacitor C _2lMinus earth voltage GND; The 3rd capacitor C _2rPositive pole meet the anode V of output node _Op, the 3rd capacitor C _2rMinus earth voltage GND; The 4th capacitor C _1rMinus earth voltage GND; The first current source I _B1Positive pole, the 3rd PMOS manage M _2lDrain electrode, the 5th PMOS manage M _1lThe grid and first capacitor C _1lPositive pole link together the first current source I _B1Minus earth voltage GND; The second current source I _B2Positive pole, the 4th PMOS manage M _2rDrain electrode, the 6th PMOS manage M _1rThe grid and second capacitor C _2lPositive pole link together the second current source I _B2Minus earth voltage GND.

The invention allows for another kind of degenerative second-order bandpass filter, it is characterized in that, adopt the NMOS pipe to realize, this second-order bandpass filter comprises NMOS pipe M _3l, the 2nd NMOS manages M _3r, the 3rd NMOS manages M _2l, the 4th NMOS manages M _2r, the 5th NMOS manages M _1l, the 6th NMOS manages M _1r, first capacitor C _1l, second capacitor C _2l, the 3rd capacitor C _2r, the 4th capacitor C _1r, the first current source I _B1With the second current source I _B2Wherein, NMOS pipe M _3lDrain electrode meet the negative terminal V of output node _Op, a NMOS manages M _3lGrid connect the input node anode V _Ip, a NMOS manages M _3lSource ground voltage GND; The 2nd NMOS manages M _3rDrain electrode meet the anode V of output node _Op, the 2nd NMOS manages M _3rGrid connect the input node negative terminal V _In, the 2nd NMOS manages M _3rSource ground voltage GND; The 3rd NMOS manages M _2lGrid meet the negative terminal V of output node _On, the 3rd NMOS manages M _2lSource ground voltage GND; The 4th NMOS manages M _2rGrid meet the anode V of output node _Op, the 4th NMOS manages M _2rSource ground voltage GND; The 5th NMOS manages M _1lDrain electrode meet supply voltage VDD, the 5th NMOS manages M _1lSource electrode meet the negative terminal V of output node _OnThe 6th NMOS manages M _1rDrain electrode meet supply voltage VDD, the 6th NMOS manages M _1rSource electrode meet the anode V of output node _OpFirst capacitor C _1lNegative pole meet supply voltage VDD; Second capacitor C _2lPositive pole meet the negative terminal V of output node _On, second capacitor C _2lNegative pole meet supply voltage VDD; The 3rd capacitor C _2rPositive pole meet the anode V of output node _Op, the 3rd capacitor C _2rNegative pole meet supply voltage VDD; The 4th capacitor C _1rNegative pole meet supply voltage VDD; The first current source I _B1Positive pole, the 3rd NMOS manage M _2lDrain electrode, the 5th NMOS manage M _1lThe grid and first capacitor C _1lPositive pole link together the first current source I _B1Negative pole meet supply voltage VDD; The second current source I _B2Positive pole, the 4th NMOS manage M _2rDrain electrode, the 6th NMOS manage M _1rThe grid and second capacitor C _2lPositive pole link together the second current source I _B2Negative pole meet supply voltage VDD.

Characteristics of the present invention and effect:

The present invention is based on negative-feedback technology, do not need common mode feedback circuit, reduce power consumption effectively; Only used eight transistors to realize a double-two-order unit, realize that the fourth-order band-pass filter only needs 16 transistors, symmetrical configuration is simple, is easy to design, has reduced the complexity of band pass filter circuit structure effectively.

The present invention can also further control PMOS pipe and the 2nd PMOS pipe is adjusted passband gain with the mutual conductance ratio of the 5th PMOS pipe and the 6th PMOS pipe.

Description of drawings

Fig. 1 is the schematic diagram of transconductance cell in the existing band pass filter;

Fig. 2 is a kind of schematic diagram based on degenerative second-order bandpass filter that the present invention proposes;

Fig. 3 is a kind of schematic diagram based on degenerative second-order bandpass filter that the present invention proposes;

Fig. 4 is the amplitude transmission curve of the 4 rank active band-pass filters that propose of the present invention.

Embodiment

Degenerative second-order bandpass filter of the present invention reaches embodiment in conjunction with the accompanying drawings and is described in detail as follows:

A kind of degenerative second-order bandpass filter that the present invention proposes as shown in Figure 2, is characterized in that, adopts the PMOS pipe to realize, this second-order bandpass filter comprises PMOS pipe M _3l, the 2nd PMOS manages M _3r, the 3rd PMOS manages M _2l, the 4th PMOS manages M _2r, the 5th PMOS manages M _1l, the 6th PMOS manages M _1r, first capacitor C _1l, second capacitor C _2l, the 3rd capacitor C _2r, the 4th capacitor C _1r, the first current source I _B1With the second current source I _B2Wherein, PMOS pipe M _3lDrain electrode meet the negative terminal V of output node _Op, a PMOS manages M _3lGrid connect the input node anode V _Ip, a PMOS manages M _3lSource electrode meet supply voltage VDD; The 2nd PMOS manages M _3rDrain electrode meet the anode V of output node _Op, the 2nd PMOS manages M _3rGrid connect the input node negative terminal V _In, the 2nd PMOS manages M _3rSource electrode meet supply voltage VDD; The 3rd PMOS manages M _2lGrid meet the negative terminal V of output node _On, the 3rd PMOS manages M _2lSource electrode meet supply voltage VDD; The 4th PMOS manages M _2rGrid meet the anode V of output node _Op, the 4th PMOS manages M _2rSource electrode meet supply voltage VDD; The 5th PMOS manages M _1lGrounded drain voltage GND, the 5th PMOS manages M _1lSource electrode meet the negative terminal V of output node _OnThe 6th PMOS manages M _1rGrounded drain voltage GND, the 6th PMOS manages M _1rSource electrode meet the anode V of output node _OpFirst capacitor C _1lMinus earth voltage GND; Second capacitor C _2lPositive pole meet the negative terminal V of output node _On, second capacitor C _2lMinus earth voltage GND; The 3rd capacitor C _2rPositive pole meet the anode V of output node _Op, the 3rd capacitor C _2rMinus earth voltage GND; The 4th capacitor C _1rMinus earth voltage GND; The first current source I _B1Positive pole, the 3rd PMOS manage M _2lDrain electrode, the 5th PMOS manage M _1lThe grid and first capacitor C _1lPositive pole link together the first current source I _B1Minus earth voltage GND; The second current source I _B2Positive pole, the 4th PMOS manage M _2rDrain electrode, the 6th PMOS manage M _1rThe grid and second capacitor C _2lPositive pole link together the second current source I _B2Minus earth voltage GND.

The another kind of degenerative second-order bandpass filter that the present invention proposes is characterized in that as shown in Figure 3, adopts the NMOS pipe to realize, this second-order bandpass filter comprises NMOS pipe M _3l, the 2nd NMOS manages M _3r, the 3rd NMOS manages M _2l, the 4th NMOS manages M _2r, the 5th NMOS manages M _1l, the 6th NMOS manages M _1r, first capacitor C _1l, second capacitor C _2l, the 3rd capacitor C _2r, the 4th capacitor C _1r, the first current source I _B1With the second current source I _B2Wherein, NMOS pipe M _3lDrain electrode meet the negative terminal V of output node _Op, a NMOS manages M _3lGrid connect the input node anode V _Ip, a NMOS manages M _3lSource ground voltage GND; The 2nd NMOS manages M _3rDrain electrode meet the anode V of output node _Op, the 2nd NMOS manages M _3rGrid connect the input node negative terminal V _In, the 2nd NMOS manages M _3rSource ground voltage GND; The 3rd NMOS manages M _2lGrid meet the negative terminal V of output node _On, the 3rd NMOS manages M _2lSource ground voltage GND; The 4th NMOS manages M _2rGrid meet the anode V of output node _Op, the 4th NMOS manages M _2rSource ground voltage GND; The 5th NMOS manages M _1lDrain electrode meet supply voltage VDD, the 5th NMOS manages M _1lSource electrode meet the negative terminal V of output node _OnThe 6th NMOS manages M _1rDrain electrode meet supply voltage VDD, the 6th NMOS manages M _1rSource electrode meet the anode V of output node _OpFirst capacitor C _1lNegative pole meet supply voltage VDD; Second capacitor C _2lPositive pole meet the negative terminal V of output node _On, second capacitor C _2lNegative pole meet supply voltage VDD; The 3rd capacitor C _2rPositive pole meet the anode V of output node _Op, the 3rd capacitor C _2rNegative pole meet supply voltage VDD; The 4th capacitor C _1rNegative pole meet supply voltage VDD; The first current source I _B1Positive pole, the 3rd NMOS manage M _2lDrain electrode, the 5th NMOS manage M _1lThe grid and first capacitor C _1lPositive pole link together the first current source I _B1Negative pole meet supply voltage VDD; The second current source I _B2Positive pole, the 4th NMOS manage M _2rDrain electrode, the 6th NMOS manage M _1rThe grid and second capacitor C _2lPositive pole link together the second current source I _B2Negative pole meet supply voltage VDD.

In order to illustrate that in further detail the double-two-order unit that the embodiment of the invention provides can realize band pass filter, carry out following quantitative analysis.As shown in Figure 2, if ignore output mutual conductance and transistorized parasitic capacitance, and establish PMOS pipe M _3lAnd M _3rMutual conductance be g _M3, establish PMOS pipe M _2lAnd M _2rMutual conductance be g _M2, establish PMOS pipe M _1lAnd M _1rMutual conductance be g _M1, capacitor C _1lAnd C _1rCapacitance be C ₁, capacitor C _2lAnd C _2rCapacitance be C ₂, can obtain the S territory transfer function (being that variable is the function H (s) of s) of filter thus:

$H\left(s\right)=\frac{g_{m3}}{g_{m1}}\frac{s\frac{g_{m1}}{C_2}}{s^2+s\frac{g_{m1}}{C_2}+\frac{g_{m1}{g}_{m2}}{C_1{C}_2}}---\left(2\right)$

Can obtain the characterisitic parameter of filter by following formula (2), comprise the pole characteristics angular frequency ₀, the gain of quality factor q and centre frequency place K, wherein f ₀Be the pole characteristics frequency:

${\mathrm{\ω}}_0=2\mathrm{\π}{f}_0=\sqrt{\frac{g_{m1}{g}_{m2}}{C_1{C}_2}}---\left(3\right)$

$Q=\sqrt{\frac{C_1}{C_2}\frac{g_{m1}}{g_{m2}}}---\left(4\right)$

$K=\frac{g_{m3}}{g_{m1}}---\left(5\right)$

Second-order bandpass filter shown in Figure 2 and second-order bandpass filter cascade shown in Figure 3 are formed the fourth-order band-pass filter, adopt CMOS 90nm mixed signal technology to carry out emulation, to verify correctness of the present invention.The fourth-order band-pass filter is realized the transfer function curve chart of quadravalence Butterworth mode filter, and as shown in Figure 4, the vertical axis of ordinates of this curve chart and horizontal axis represent with decibel (dB) to be the amplitude characteristic and the correspondent frequency (MHz) of unit respectively.Can learn from this curve: (1) has realized pass band filter characteristic, and centre frequency is 100MHz, and the fourth-order band-pass filter is 10 frequency multiplication places decay 40dB outside band; (2) passband gain that can know the second-order bandpass filter of realizing among Fig. 2 from formula (5) is 9.5dB.By Fig. 5 curve as can be seen, the filtering characteristic of side circuit simulation result and MATLAB modeling differs little, and upwarping by non-ideal factor in the circuit that low-frequency channel emulation occurs causes.

The present invention is based on negative-feedback technology, does not need common mode feedback circuit, reduces power consumption effectively; Only used eight transistors to realize a double-two-order unit, realize that the fourth-order band-pass filter only needs 16 transistors, symmetrical configuration is simple, is easy to design, has reduced the complexity of band pass filter circuit structure effectively.

The present invention can also adjust passband gain with the mutual conductance ratio of the 5th PMOS pipe and the 6th PMOS pipe by controlling PMOS pipe and the 2nd PMOS pipe.

Above-described specific embodiment; purpose of the present invention, technical scheme and beneficial effect are further described; institute is understood that; the above only is specific embodiments of the invention; be not limited to the present invention; within the spirit and principles in the present invention all, any modification of being made, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (2)

1. a degenerative second-order bandpass filter is characterized in that, adopts the PMOS pipe to realize, this second-order bandpass filter comprises PMOS pipe (M _3l), the 2nd PMOS manages (M _3r), the 3rd PMOS manages (M _2l), the 4th PMOS manages (M _2r), the 5th PMOS manages (M _1l), the 6th PMOS manages (M _1r), the first electric capacity (C _1l), the second electric capacity (C _2l), the 3rd electric capacity (C _2r), the 4th electric capacity (C _1r), the first current source (I _B1) and the second current source (I _B2); Wherein, PMOS pipe (M _3l) drain electrode meet the negative terminal (V of output node _On), a PMOS manages (M _3l) grid connect the input node anode (V _Ip), a PMOS manages (M _3l) source electrode connect supply voltage (VDD); The 2nd PMOS manages (M _3r) drain electrode meet the anode (V of output node _Op), the 2nd PMOS manages (M _3r) grid connect the input node negative terminal (V _In), the 2nd PMOS manages (M _3r) source electrode connect supply voltage (VDD); The 3rd PMOS manages (M _2l) grid meet the negative terminal (V of output node _On), the 3rd PMOS manages (M _2l) source electrode connect supply voltage (VDD); The 4th PMOS manages (M _2r) grid meet the anode (V of output node _Op), the 4th PMOS manages (M _2r) source electrode connect supply voltage (VDD); The 5th PMOS manages (M _1l) grounded drain voltage (GND), the 5th PMOS manages (M _1l) source electrode meet the negative terminal (V of output node _On); The 6th PMOS manages (M _1r) grounded drain voltage (GND), the 6th PMOS manages (M _1r) source electrode meet the anode (V of output node _Op); First electric capacity (the C _1l) minus earth voltage (GND); Second electric capacity (the C _2l) positive pole meet the negative terminal (V of output node _On), the second electric capacity (C _2l) minus earth voltage (GND); The 3rd electric capacity (C _2r) positive pole meet the anode (V of output node _Op), the 3rd electric capacity (C _2r) minus earth voltage (GND); The 4th electric capacity (C _1r) minus earth voltage (GND); First current source (the I _B1) positive pole, the 3rd PMOS manage (M _2l) drain electrode, the 5th PMOS manage (M _1l) the grid and the first electric capacity (C _1l) positive pole link together the first current source (I _B1) minus earth voltage (GND); Second current source (the I _B2) positive pole, the 4th PMOS manage (M _2r) drain electrode, the 6th PMOS manage (M _1r) the grid and the second electric capacity (C _2l) positive pole link together the second current source (I _B2) minus earth voltage (GND).

2. a degenerative second-order bandpass filter is characterized in that, adopts the NMOS pipe to realize, this second-order bandpass filter comprises NMOS pipe (M _3l), the 2nd NMOS manages (M _3r), the 3rd NMOS manages (M _2l), the 4th NMOS manages (M _2r), the 5th NMOS manages (M _1l), the 6th NMOS manages (M _1r), the first electric capacity (C _1l), the second electric capacity (C _2l), the 3rd electric capacity (C _2r), the 4th electric capacity (C _1r), the first current source (I _B1) and the second current source (I _B2); Wherein, NMOS pipe (M _3l) drain electrode meet the negative terminal (V of output node _On), a NMOS manages (M _3l) grid connect the input node anode (V _Ip), a NMOS manages (M _3l) source ground voltage (GND); The 2nd NMOS manages (M _3r) drain electrode meet the anode (V of output node _Op), the 2nd NMOS manages (M _3r) grid connect the input node negative terminal (V _In), the 2nd NMOS manages (M _3r) source ground voltage (G _ND); The 3rd NMOS manages (M _2l) grid meet the negative terminal (V of output node _On), the 3rd NMOS manages (M _2l) source ground voltage (GND); The 4th NMOS manages (M _2r) grid meet the anode (V of output node _Op), the 4th NMOS manages (M _2r) source ground voltage (GND); The 5th NMOS manages (M _1l) drain electrode connect supply voltage (VDD), the 5th NMOS manages (M _1l) source electrode meet the negative terminal (V of output node _On); The 6th NMOS manages (M _1r) drain electrode connect supply voltage (VDD), the 6th NMOS manages (M _1r) source electrode meet the anode (V of output node _Op); First electric capacity (the C _1l) negative pole connect supply voltage (VDD); Second electric capacity (the C _2l) positive pole meet the negative terminal (V of output node _On), the second electric capacity (C _2l) negative pole connect supply voltage (VDD); The 3rd electric capacity (C _2r) positive pole meet the anode (V of output node _Op), the 3rd electric capacity (C _2r) negative pole connect supply voltage (VDD); The 4th electric capacity (C _1r) negative pole connect supply voltage (VDD); First current source (the I _B1) positive pole, the 3rd NMOS manage (M _2l) drain electrode, the 5th NMOS manage (M _1l) the grid and the first electric capacity (C _1l) positive pole link together the first current source (I _B1) negative pole connect supply voltage (VDD); Second current source (the I _B2) positive pole, the 4th NMOS manage (M _2r) drain electrode, the 6th NMOS manage (M _1r) the grid and the second electric capacity (C _2l) positive pole link together the second current source (I _B2) negative pole connect supply voltage (VDD).

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