CN103227620A - Reconfigurable Gm_C filter circuit - Google Patents
Reconfigurable Gm_C filter circuit Download PDFInfo
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Abstract
The invention discloses a reconfigurable Gm_C filter circuit which comprises an I path in-phase signal channel, a Q path orthogonal signal channel and a transconductance gyrator group outside the channels. The circuit is characterized in that the I path in-phase signal channel and the Q path orthogonal signal channel are same Gm_C low pass filters with a trapezoid jump coupling structure; symmetrical capacitive elements in the two signal channels are connected through one transconductance gyrator in the transconductance gyrator group outside the channels; and each of the differential input end and the differential output end of each transconductance gyrator in the transconductance gyrator group outside the channels are connected with a digital switch. According to reconfigurable Gm_C filter circuit disclosed by the invention, a Gm_C filter is configured to two working modes, namely, a plurality of band-pass filters and low pass filters through the digital switches, so that switching between the plurality of band-pass filters and low pass filters of the Gm_C filter in the on-chip trapezoid jump coupling structure is realized. Configuration switching among three-order, five-order, seven-order or even higher order of the filters is realized, and the reconfigurable Gm_C filter circuit can be widely applied to electronic communication systems.
Description
Technical field
The present invention relates to filter circuit, be specifically related to reconfigurable Gm_C filter circuit.
Background technology
Filter is that a kind of frequency to input signal has optionally two-port network.Its amplitude-frequency response comprises passband, transition band and stopband, it allows the signal in free transmission range to pass through with smaller decay, signal in transition band is subjected to decay in various degree, and the signal in stopband is subjected to decaying significantly and be inhibited, signal not only can change its amplitude according to the difference of frequency after by filter accordingly, and shaping to a certain degree also can appear in its phase characteristic simultaneously.
Along with the continuous progress of information technology and integrated circuit technique, active filter obtains application more and more widely in transceiver.At present, the frequency difference of filtering as required, active filter mainly comprises Gm-C filter, RC filter, MOSFET-C filter and SC filter etc.The Gm-C filter is compared to the active filter of other type, has operating frequency height, simple in structure, low in energy consumption and be easy to advantages such as tuning, is more favored in the transceiver of low-power consumption.The implementation of integrated Gm-C filter has a variety of, commonly used structures to mainly contain cascade structure and trapezoidal jumping coupling structure on the sheet, and the Gm unit in the trapezoidal jumping coupling structure is subjected to the influence of direct current offset very little, and circuit element parameter sensitivity is low.
The proposition of software and radio technique, provide effectively and the solution of safety making up single chip integrated multi-mode, multifrequency and multi-functional transceiver, this also has higher requirement to wireless transceiver system simultaneously, needs to consider architectural framework, broadband programmable, configurable radio frequency and intermediate frequency technology etc.Multimode multi-frequency radio transceiver is based on configurable if architectures mostly at present, to reduce chip cost and power consumption, this requires the analog intermediate frequency filter to have plural number and is with configurable and programmable bandwidth and centre frequency logical and two kinds of mode of operations of low pass, filter order.The present invention is directed to the problems referred to above thus and proposed a kind of logical and low pass of plural number band that can be configured to, also can be configured to the Gm_C filter of five stairsteppings jumping coupling structure and the Gm_C filter that three stairsteppings are jumped the coupling structure under the mode of operation arbitrarily simultaneously.
Summary of the invention
Technical problem to be solved by this invention is the Gm_C filter circuit that provides reconfigurable.
In order to solve the problems of the technologies described above, technical scheme of the present invention is, reconfigurable Gm_C filter circuit, comprise: I road in-phase signal passage, Q road quadrature signal path and be positioned at the outer mutual conductance gyrator group of passage is characterized in that: I road in-phase signal passage and Q road quadrature signal path are the Gm_C low pass filter of identical trapezoidal jumping coupling structure; The capacitive element of the symmetry in two signalling channels is connected by a mutual conductance gyrator in the outer mutual conductance gyrator group of passage, and the differential input end and the difference output end of each the mutual conductance gyrator in the outer mutual conductance gyrator group of passage all are connected with a digital switch.
The present invention can be configured to complex bandpass filters and two kinds of mode of operations of low pass filter by digital switch, when the digital switch on being connected on the mutual conductance gyrator is all closed, filter is a complex bandpass filters, when above-mentioned switch all disconnects, filter is a low pass filter, and the plural number band of the Gm_C filter of coupling structure leads to and the switching of low pass thereby realization sheet upper trapezoid is jumped; After turn-offing the frequency displacement network, can realize that complex filter arrives the conversion of real filter, and have and utilize programming device to carry out the repeatedly characteristic of repeated configuration logic state.Change the structure of circuit as required when work, thereby it is flexible, easy that whole system is had, the hardware resource reusable is easy to multiple superperformances such as upgrading.
According to a kind of preferred version of reconfigurable Gm_C filter circuit of the present invention, this I road in-phase signal passage and Q road quadrature signal path are the Gm_C low pass filter of identical trapezoidal jumping coupling structure; This Gm_C low pass filter comprises that continuous successively operational transconductance amplifier, input side artifical resistance, mutual conductance gyrator one are to mutual conductance gyrator four, outlet side artifical resistance; And the difference output end of mutual conductance gyrator two is connected with the differential input end of mutual conductance gyrator three by digital switch 25, digital switch 26 respectively; The difference output end that connects the mutual conductance gyrator four of outlet side artifical resistance is connected with the differential input end of outlet side artifical resistance by digital switch 27, digital switch 28 respectively; One of them differential input end of outlet side artifical resistance is by the input of digital switch 33 linking number word switch 25, and another differential input end of outlet side artifical resistance is by the input of digital switch 34 linking number word switch 26.
Thus, I road in-phase signal passage constitutes the Gm_C low pass filter that 5 identical stairsteppings are jumped the coupling structure with Q road quadrature signal path, by the bias current of digital switch and mutual conductance gyrator is controlled, realize can be configured under any mode of operation five rank filters and three rank filters.
According to a kind of preferred version of reconfigurable Gm_C filter circuit of the present invention, second digital switch 25, mutual conductance gyrator five, mutual conductance gyrator six and second digital switch 27 also have been linked in sequence between the connected node of one of them difference output end of mutual conductance gyrator two with digital switch 25 and digital switch 33; Second digital switch 26, mutual conductance gyrator five, mutual conductance gyrator six and second digital switch 28 also have been linked in sequence between the connected node of another difference output end of mutual conductance gyrator two with digital switch 26 and digital switch 34; And second digital switch 27 is connected with a difference output end of mutual conductance gyrator two by second digital switch 33 with the connected node of digital switch 25 and digital switch 33; Second digital switch 28 is connected with another difference output end of mutual conductance gyrator two by second digital switch 34 with the connected node of digital switch 26 and digital switch 34.
Thus, in-phase signal passage in I road constitutes the Gm_C low pass filter that 7 identical stairsteppings are jumped the coupling structure with Q road quadrature signal path.By the bias current of digital switch and mutual conductance gyrator is controlled, realize can be configured under any mode of operation seven rank filters, five rank filters or three rank filters.
According to a kind of preferred version of reconfigurable Gm_C filter circuit of the present invention, described digital switch includes inverter INV, PMOS pipe M1 and NMOS pipe M2; The source electrode of described PMOS pipe M1 is connected the input as digital switch with the drain electrode of described NMOS pipe M2, the drain electrode of described PMOS pipe M1 is connected the output as digital switch with the source electrode of described NMOS pipe M2, the grid of described NMOS pipe M2 is the control end of digital switch, and is connected with the input of inverter INV; The output of inverter INV is connected with the grid of PMOS pipe M1.
A kind of preferred version according to reconfigurable Gm_C filter circuit of the present invention, described mutual conductance gyrator is that the output of two operational transconductance amplifiers and input interconnection are constituted, one of them operational transconductance amplifier is that anti-phase input connects, and another operational transconductance amplifier is that the homophase input connects.
The beneficial effect of reconfigurable Gm_C filter circuit of the present invention is: the present invention is complex bandpass filters and two kinds of mode of operations of low pass filter by digital switch with the Gm_C filter configuration, thereby realizes that the sheet upper trapezoid jumps the logical switching with low pass of the plural number band of Gm_C filter of coupling structure; And can realize filter three rank and five rank and seven rank even the more configuration switching of high-order under the mode of operation arbitrarily, realize the multiplexing of circuit, thereby saved chip area, reduced system power dissipation, and it is flexible, easy that whole system is had concurrently, is easy to multiple superperformances such as upgrading; The present invention also can be by changing corresponding mutual conductance the mode of bias current realize the able to programme of filter bandwidht and centre frequency, can be widely used in the electronic communication system, have a good application prospect.
Description of drawings
Fig. 1 is the structural representation of embodiment 1.
Fig. 2 is the forward part structural representation of embodiment 2.
Fig. 3 is the rear section structural representation of embodiment 2.
Fig. 4 is the structural representation of digital switch.
Fig. 5 is the equivalent circuit diagram of Fig. 4.
Fig. 6 is the structural representation that Fig. 1 is transformed to complex bandpass filters.
Fig. 7 is the structural representation that Fig. 1 is transformed to low pass filter.
Embodiment
Referring to Fig. 1 to Fig. 3, reconfigurable Gm_C filter circuit, comprise: I road in-phase signal passage, Q road quadrature signal path and be positioned at the outer mutual conductance gyrator group of passage is characterized in that: I road in-phase signal passage and Q road quadrature signal path are the Gm_C low pass filter of identical trapezoidal jumping coupling structure; The capacitive element of the symmetry in two signalling channels is connected by a mutual conductance gyrator in the outer mutual conductance gyrator group of passage, and the differential input end and the difference output end of each the mutual conductance gyrator in the outer mutual conductance gyrator group of passage all are connected with a digital switch.
This I road in-phase signal passage and Q road quadrature signal path are the Gm_C low pass filter of identical trapezoidal jumping coupling structure; This Gm_C low pass filter comprises that continuous successively operational transconductance amplifier, input side artifical resistance, mutual conductance gyrator one are to mutual conductance gyrator four, outlet side artifical resistance; And the difference output end of mutual conductance gyrator two is connected with the differential input end of mutual conductance gyrator three by digital switch 25, digital switch 26 respectively; The difference output end that connects the mutual conductance gyrator four of outlet side artifical resistance is connected with the differential input end of outlet side artifical resistance by digital switch 27, digital switch 28 respectively; One of them differential input end of outlet side artifical resistance is by the input of digital switch 33 linking number word switch 25, and another differential input end of outlet side artifical resistance is by the input of digital switch 34 linking number word switch 26.Thus, I road in-phase signal passage constitutes the Gm_C low pass filter that 5 identical stairsteppings are jumped the coupling structure with Q road quadrature signal path, by the bias current of digital switch and mutual conductance gyrator is controlled, realize can be configured under any mode of operation five rank filters and three rank filters.
According to above-mentioned principle, the present invention can also realize the switching of seven rank complex bandpass filters and five rank complex bandpass filters and three rank complex bandpass filters, is specially also be linked in sequence between the connected node of one of them difference output end with digital switch 25 and digital switch 33 of mutual conductance gyrator two second digital switch 25, mutual conductance gyrator five, mutual conductance gyrator six and second digital switch 27; Second digital switch 26, mutual conductance gyrator five, mutual conductance gyrator six and second digital switch 28 also have been linked in sequence between the connected node of another difference output end of mutual conductance gyrator two with digital switch 26 and digital switch 34; And second digital switch 27 is connected with a difference output end of mutual conductance gyrator two by second digital switch 33 with the connected node of digital switch 25 and digital switch 33; Second digital switch 28 is connected with another difference output end of mutual conductance gyrator two by second digital switch 34 with the connected node of digital switch 26 and digital switch 34.
Below in conjunction with specific embodiment, the present invention is described in detail:
Embodiment 1: referring to Fig. 1, reconfigurable Gm_C filter is the five stairsteppings jumping coupling low pass filter of same structure and is positioned at passage outer mutual conductance gyrator group and digital switch by I, Q two passages and constitutes.Wherein, I road five stairsteppings jumping coupling low pass filter is made of operational transconductance amplifier Gm1, input side artifical resistance Gm2, the first mutual conductance gyrator, one to first mutual conductance gyrator four, outlet side artifical resistance Gm11, electric capacity one～electric capacity six; The first mutual conductance gyrator one is made of operational transconductance amplifier Gm3, Gm4; The first mutual conductance gyrator two is made of operational transconductance amplifier Gm5, Gm6, the first mutual conductance gyrator three is made of operational transconductance amplifier Gm7, Gm8, the first mutual conductance gyrator four is made of operational transconductance amplifier Gm9, Gm10, and electric capacity one is made of capacitor C 1-1, C1-2 parallel connection; Electric capacity two is by capacitor C 2-1, C2-2 is in parallel to be constituted, electric capacity three is by capacitor C 3-1, C3-2 is in parallel to be constituted, electric capacity four is by capacitor C 4-1, C4-2 is in parallel to be constituted, electric capacity five is by capacitor C 5-1, C5-2 is in parallel to be constituted, electric capacity six is by capacitor C 6-1, C6-2 is in parallel to be constituted, electric capacity one two ends are connected on the difference output end of operational transconductance amplifier Gm1 respectively, electric capacity two two ends are connected on the difference output end of the first mutual conductance gyrator one respectively, electric capacity three two ends are connected on the difference output end of the first mutual conductance gyrator two respectively, electric capacity four two ends are connected on the differential input end of the first mutual conductance gyrator three respectively, electric capacity five two ends are connected on the difference output end of the first mutual conductance gyrator three respectively, and electric capacity six two ends connect the difference output end of the first mutual conductance gyrator four respectively;
Q road five stairsteppings are jumped the coupling low pass filter and are made of operational transconductance amplifier Gm24, input side artifical resistance Gm25, the second mutual conductance gyrator, one to second mutual conductance gyrator four, outlet side artifical resistance Gm34, electric capacity seven～electric capacity 12; The second mutual conductance gyrator one is made of operational transconductance amplifier Gm26, Gm27; The second mutual conductance gyrator two is made of operational transconductance amplifier Gm28, Gm29, and the second mutual conductance gyrator three is made of operational transconductance amplifier Gm30, Gm31, and the second mutual conductance gyrator four is made of operational transconductance amplifier Gm32, Gm33; Electric capacity seven is made of capacitor C 7-1, C7-2 parallel connection; Electric capacity eight is by capacitor C 8-1, C8-2 is in parallel to be constituted, electric capacity nine is by capacitor C 9-1, C9-2 is in parallel to be constituted, electric capacity ten is by capacitor C 10-1, C10-2 is in parallel to be constituted, electric capacity 11 is by capacitor C 11-1, C11-2 is in parallel to be constituted, electric capacity 12 is by capacitor C 12-1, C12-2 is in parallel to be constituted, electric capacity seven two ends are connected on the difference output end of operational transconductance amplifier Gm24 respectively, electric capacity eight two ends are connected on the difference output end of the second mutual conductance gyrator one respectively, electric capacity nine two ends are connected on the difference output end of the second mutual conductance gyrator two respectively, electric capacity ten two ends are connected on the differential input end of the second mutual conductance gyrator three respectively, electric capacity 11 two ends are connected on the difference output end of the second mutual conductance gyrator three respectively, and electric capacity 12 two ends connect the difference output end of the second mutual conductance gyrator four respectively;
Be positioned at the outer mutual conductance gyrator group of passage and comprise that mutual conductance gyrator nine is to mutual conductance gyrator 14; Mutual conductance gyrator nine is made of operational transconductance amplifier Gm12, Gm13, and its differential input end connects the two ends of electric capacity one respectively by digital switch SW1, SW2, and difference output end connects the two ends of electric capacity seven respectively by digital switch SW3, SW4; Mutual conductance gyrator ten is made of operational transconductance amplifier Gm14, Gm15, and its differential input end connects the two ends of electric capacity two respectively by digital switch SW5, SW6, and difference output end connects the two ends of electric capacity eight respectively by digital switch SW7, SW8; Mutual conductance gyrator 11 is made of operational transconductance amplifier Gm16, Gm17, and its differential input end connects the two ends of electric capacity three respectively by digital switch SW9, SW10, and difference output end connects the two ends of electric capacity nine respectively by digital switch SW11, SW12; Mutual conductance gyrator 12 is made of operational transconductance amplifier Gm18, Gm19, and its differential input end connects the two ends of electric capacity four respectively by digital switch SW13, SW14, and difference output end connects the two ends of electric capacity ten respectively by digital switch SW15, SW16; Mutual conductance gyrator 13 is made of operational transconductance amplifier Gm20, Gm21, and its differential input end connects the two ends of electric capacity five respectively by digital switch SW17, SW18, and difference output end connects the two ends of electric capacity 11 respectively by digital switch SW19, SW20; Mutual conductance gyrator 14 is made of operational transconductance amplifier Gm22, Gm23, and its differential input end connects the two ends of electric capacity six respectively by digital switch SW21, SW22, and difference output end connects the two ends of electric capacity 12 respectively by digital switch SW23, SW24.
The switching of complex bandpass filters and low pass filter is disposed by the digital switch of connecting with gyrator between I, Q two passages.When being connected on the whole closure of the digital switch SW1～SW24 of mutual conductance gyrator nine to mutual conductance gyrator 14, filter is a complex bandpass filters, as Fig. 6; When above-mentioned switch all disconnected, filter was a low pass filter, as Fig. 7.
When digital switch SW25～SW28, SW33, SW34 are inserted I road in-phase signal passage, digital switch SW29～SW32, SW35, SW36 insert Q road quadrature signal path, can realize can be configured under any mode of operation five rank filters or three rank filters; Be about to digital switch SW25～SW26 and be connected the difference output end of the first mutual conductance gyrator two and the differential input end of the first mutual conductance gyrator three; Digital switch SW27～SW28 is connected the difference output end of the first mutual conductance gyrator four and the differential input end of outlet side artifical resistance Gm11, and digital switch SW33～SW34 is connected the difference output end of the first mutual conductance gyrator two and the differential input end of outlet side artifical resistance Gm11; Digital switch SW29～SW30 is connected the difference output end of the second mutual conductance gyrator two and the differential input end of the second mutual conductance gyrator three; Digital switch SW31～SW32 is connected the difference output end of the second mutual conductance gyrator four and the differential input end of outlet side artifical resistance Gm34, and digital switch SW33～SW34 is connected the difference output end of the second mutual conductance gyrator two and the differential input end of outlet side artifical resistance Gm34; The switching of five rank filters and three rank filters is controlled by digital switch SW25～SW32:
At the I passage, when digital switch SW25～SW28 closure, when digital switch SW33, SW34 disconnected, filter constituted the Gm_C low pass filter that five stairsteppings are jumped the coupling structure; When digital switch SW25～SW38 disconnection, digital switch SW33, SW34 closure, when simultaneously the bias current among operational transconductance amplifier Gm7～Gm10 all being changed to zero, then filter constitutes the Gm_C low pass filter that becomes three stairsteppings jumping coupling structure.
At the Q passage, when digital switch SW29～SW32 closure, when digital switch SW35, SW36 disconnected, filter constituted the Gm_C low pass filter that five stairsteppings are jumped the coupling structure; When digital switch SW29～SW32 disconnection, digital switch SW35, SW36 closure, when simultaneously the bias current among operational transconductance amplifier Gm30～Gm33 all being changed to zero, then filter constitutes the Gm_C low pass filter that becomes three stairsteppings jumping coupling structure.
When the switch of I, Q passage disposes simultaneously in a manner described, can realize the switching of five rank complex bandpass filters and three rank complex bandpass filters.When switching to three rank complex bandpass filters,, make the power consumption of Gm_C filter circuit reduce because the bias current among operational transconductance amplifier Gm7～Gm10, Gm18～Gm23, the Gm30～Gm33 is zero.
Embodiment 2: referring to Fig. 2 and Fig. 3, reconfigurable Gm_C filter is the seven stairsteppings jumping coupling low pass filter of same structure and is positioned at passage outer mutual conductance gyrator group and digital switch by I, Q two passages and constitutes.Difference from Example 1 is:
I road seven stairsteppings are jumped the coupling low pass filter by operational transconductance amplifier Gm1, input side artifical resistance Gm2, the first mutual conductance gyrator one, the first mutual conductance gyrator two, operational transconductance amplifier Gm7A, the first mutual conductance gyrator five that Gm8A constitutes, operational transconductance amplifier Gm9A, the first mutual conductance gyrator six that Gm10A constitutes, the first mutual conductance gyrator three, the first mutual conductance gyrator four, outlet side artifical resistance Gm11, electric capacity one～electric capacity three, electric capacity four A～electric capacity six A, electric capacity four～electric capacity six constitutes; Electric capacity four A are made of capacitor C 4-1A, C4-2A parallel connection, and electric capacity five A are made of capacitor C 5-1A, C5-2A parallel connection, and electric capacity six A are made of capacitor C 6-1A, C6-2A parallel connection; Electric capacity four A two ends are connected on the differential input end of the first mutual conductance gyrator five respectively, and electric capacity five A two ends are connected on the difference output end of the first mutual conductance gyrator five respectively, and electric capacity six A two ends connect the difference output end of the first mutual conductance gyrator six respectively.
The formation of Q road quadrature signal path is identical with I road in-phase signal passage formation, this tired stating.
Be positioned at the outer mutual conductance gyrator group of passage and comprise that mutual conductance gyrator nine is to mutual conductance gyrator 17; The differential input end of mutual conductance gyrator 15 connects the two ends of electric capacity four A respectively by digital switch SW13A, SW14A, the differential input end of mutual conductance gyrator 16 connects the two ends of electric capacity five A respectively by digital switch SW17A, SW18A, the differential input end of mutual conductance gyrator 17 connects the two ends of electric capacity six A respectively by digital switch SW21A, SW22A; Mutual conductance gyrator 15 to the difference output end of mutual conductance gyrator 17 connects the two ends of the corresponding electric capacity of Q road quadrature signal path respectively by digital switch, this not tired stating.
When digital switch SW25～SW28, SW33, SW34, SW25A～SW28A, SW33A, SW34A are inserted I road in-phase signal passage, digital switch SW29～SW32, SW35, SW36, SW29A～SW32A, SW35A, SW36A insert Q road quadrature signal path, can realize can be configured under any mode of operation seven rank filters, five rank filters or three rank filters; Being specially digital switch SW25A～SW26A is connected between the differential input end of the difference output end of the first mutual conductance gyrator two and the first mutual conductance gyrator five; Be connected with digital switch SW27A between one of them difference output end of the connected node of digital switch SW25 and digital switch SW33 and the first mutual conductance gyrator six; Be connected with digital switch SW28A between another difference output end of the connected node of digital switch SW26 and digital switch SW34 and the first mutual conductance gyrator six; And digital switch SW27A is connected with a difference output end of the first mutual conductance gyrator two by digital switch SW33A with the connected node of digital switch SW25 and digital switch SW33; Digital switch SW28A is connected with another difference output end of the first mutual conductance gyrator two by digital switch SW34A with the connected node of digital switch SW26 and digital switch SW34; The method that digital switch SW29～SW32, SW35, SW36, SW29A～SW32A, SW35A, SW36A insert Q road quadrature signal path is identical with I road in-phase signal passage, this not tired stating.
At the I passage, when digital switch SW25～SW28, SW25A～SW28A closure, when digital switch SW33, SW34, SW33A, SW34A disconnection, filter constitutes the Gm_C low pass filter that seven stairsteppings are jumped the coupling structure; When digital switch SW25～SW28, SW33A～SW34A closure, when digital switch SW25A～SW28A, SW33, SW34 disconnection, when simultaneously the bias current among operational transconductance amplifier Gm7A～Gm10A all being changed to zero, filter constitutes the Gm_C low pass filter that five stairsteppings are jumped the coupling structure; When digital switch SW25～SW28, SW25A～SW28A disconnects, digital switch SW33A, SW34A, SW33, SW34 closure, when simultaneously the bias current among operational transconductance amplifier Gm7～Gm10, the Gm7A～Gm10A all being changed to zero, then filter constitutes the Gm_C low pass filter that becomes three stairsteppings jumping coupling structure.
At the Q passage, when digital switch SW29～SW32, SW29A～SW32A closure, when digital switch SW35, SW36, SW35A, SW36A disconnection, filter constitutes the Gm_C low pass filter that seven stairsteppings are jumped the coupling structure; When digital switch SW29～SW32, SW35A～SW36A closure, when digital switch SW29A～SW32A, SW35, SW36 disconnection, when simultaneously the bias current among operational transconductance amplifier Gm30A～Gm33A all being changed to zero, filter constitutes the Gm_C low pass filter that five stairsteppings are jumped the coupling structure; When digital switch SW29～SW32, SW29A～SW32A disconnects, digital switch SW35, SW36, SW35A, SW36A closure, when simultaneously the bias current among operational transconductance amplifier Gm30～Gm33, the Gm30A～Gm33A all being changed to zero, then filter constitutes the Gm_C low pass filter that becomes three stairsteppings jumping coupling structure.
Referring to Fig. 4,5, in the above-described embodiments, described digital switch includes inverter INV, PMOS pipe M1 and NMOS pipe M2; The source electrode of described PMOS pipe M1 is connected the input as digital switch with the drain electrode of described NMOS pipe M2, the drain electrode of described PMOS pipe M1 is connected the output as digital switch with the source electrode of described NMOS pipe M2, the grid of described NMOS pipe M2 is the control end of digital switch, and is connected with the input of inverter INV; The output of inverter INV is connected with the grid of PMOS pipe M1.
In the above-described embodiments, described mutual conductance gyrator is that the output of two operational transconductance amplifiers and input interconnection are constituted, and one of them operational transconductance amplifier is anti-phase input connection, and another operational transconductance amplifier is a homophase input connection.With mutual conductance gyrator nine is the example explanation: mutual conductance gyrator nine is made of operational transconductance amplifier Gm11, Gm12, the input anode of operational transconductance amplifier Gm11 connects the output negative terminal of operational transconductance amplifier Gm12, the input negative terminal of operational transconductance amplifier Gm11 connects the output plus terminal of operational transconductance amplifier Gm12, the output plus terminal of operational transconductance amplifier Gm11 connects the input anode of operational transconductance amplifier Gm12, and the output negative terminal of operational transconductance amplifier Gm11 connects the input negative terminal of operational transconductance amplifier Gm12.
According to above-mentioned principle, the present invention can also realize the more switching of high-order complex bandpass filters and seven rank, five rank complex bandpass filters and three rank complex bandpass filters, this tired stating.
The transconductance value of Gm-C filter except with operational transconductance amplifier in form mutual conductance transistor size have outside the Pass, main directly related with its quiescent bias current.Because designed good operational transconductance amplifier wherein transistor size after chip manufacturing can not change, can change its bias current value, thereby change its transconductance value, so the control of filter bandwidht and centre frequency can only realize by the mode that changes its corresponding mutual conductance Gm electric current, corresponding bias current is designed to programmable, thereby can realize the able to programme of filter bandwidht and centre frequency.
Above the specific embodiment of the present invention is described, still, the scope that is not limited only to embodiment of the present invention's protection.
Claims (5)
1. reconfigurable Gm_C filter circuit, comprise: I road in-phase signal passage, Q road quadrature signal path and be positioned at the outer mutual conductance gyrator group of passage is characterized in that: I road in-phase signal passage and Q road quadrature signal path are the Gm_C low pass filter of identical trapezoidal jumping coupling structure; The capacitive element of the symmetry in two signalling channels is connected by a mutual conductance gyrator in the outer mutual conductance gyrator group of passage, and the differential input end and the difference output end of each the mutual conductance gyrator in the outer mutual conductance gyrator group of passage all are connected with a digital switch.
2. reconfigurable Gm_C filter circuit according to claim 1 is characterized in that: this I road in-phase signal passage and Q road quadrature signal path are the Gm_C low pass filter of identical trapezoidal jumping coupling structure; This Gm_C low pass filter comprises that continuous successively operational transconductance amplifier, input side artifical resistance, mutual conductance gyrator one are to mutual conductance gyrator four, outlet side artifical resistance; And the difference output end of mutual conductance gyrator two is connected with the differential input end of mutual conductance gyrator three by digital switch 25, digital switch 26 respectively; The difference output end that connects the mutual conductance gyrator four of outlet side artifical resistance is connected with the differential input end of outlet side artifical resistance by digital switch 27, digital switch 28 respectively; One of them differential input end of outlet side artifical resistance is by the input of digital switch 33 linking number word switch 25, and another differential input end of outlet side artifical resistance is by the input of digital switch 34 linking number word switch 26.
3. reconfigurable Gm_C filter circuit according to claim 2 is characterized in that: second digital switch 25, mutual conductance gyrator five, mutual conductance gyrator six and second digital switch 27 also have been linked in sequence between the connected node of one of them difference output end of mutual conductance gyrator two with digital switch 25 and digital switch 33; Second digital switch 26, mutual conductance gyrator five, mutual conductance gyrator six and second digital switch 28 also have been linked in sequence between the connected node of another difference output end of mutual conductance gyrator two with digital switch 26 and digital switch 34; And second digital switch 27 is connected with a difference output end of mutual conductance gyrator two by second digital switch 33 with the connected node of digital switch 25 and digital switch 33; Second digital switch 28 is connected with another difference output end of mutual conductance gyrator two by second digital switch 34 with the connected node of digital switch 26 and digital switch 34.
4. according to claim 1 or 2 or 3 described reconfigurable Gm_C filter circuits, it is characterized in that: described digital switch includes inverter (INV), PMOS pipe (M1) and NMOS pipe (M2); The drain electrode that the source electrode of described PMOS pipe (M1) and described NMOS manage (M2) is connected the input as digital switch, the source electrode that the drain electrode of described PMOS pipe (M1) and described NMOS manage (M2) is connected the output as digital switch, the grid of described NMOS pipe (M2) is the control end of digital switch, and is connected with the input of inverter (INV); The output of inverter (INV) is connected with the grid of PMOS pipe (M1).
5. reconfigurable Gm_C filter circuit according to claim 4, it is characterized in that: described mutual conductance gyrator constitutes for output and the input interconnection with two operational transconductance amplifiers, one of them operational transconductance amplifier is that anti-phase input connects, and another operational transconductance amplifier is that the homophase input connects.
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| CN109565291B (en) * | 2016-08-16 | 2020-10-30 | 高通股份有限公司 | Center frequency and Q tuning of biquad filters through clipping oscillation based calibration |
| CN108418568A (en) * | 2018-01-26 | 2018-08-17 | 山东超越数控电子股份有限公司 | A kind of current multiplexing formula low-pass filter |
| CN108923768A (en) * | 2018-07-02 | 2018-11-30 | 北京无线电测量研究所 | Numerical control complex bandpass filters chip |
| CN111756348A (en) * | 2020-06-18 | 2020-10-09 | 哈尔滨工业大学 | N-path band-pass filter with configurable transconductance capacitor |
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