CN103543310A - Oscillograph with frequency response compensation circuit - Google Patents
Oscillograph with frequency response compensation circuit Download PDFInfo
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- CN103543310A CN103543310A CN201210238510.3A CN201210238510A CN103543310A CN 103543310 A CN103543310 A CN 103543310A CN 201210238510 A CN201210238510 A CN 201210238510A CN 103543310 A CN103543310 A CN 103543310A
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Abstract
The invention discloses an oscillograph with a frequency response compensation circuit. The oscillograph comprises a front-end circuit, an AD (analog/digital) converter circuit and at least one RLC (radio link control) series resonance circuit, wherein the front-end circuit comprises a signal inputting module, an inputting resistor module and an analog front-end amplifying circuit module which are successively connected with one another in series; one ends of the RLC series resonance circuits are grounded; the other ends of the RLC series resonance circuits are connected to a series connection line between the signal inputting module and the inputting resistor module, or are connected to a series connection line between the inputting resistor module and the analog front-end amplifying circuit module; the RLC series resonance circuits are used for compensating frequency response of the front-end circuit when at least one certain frequency has a crest; and the resonance frequency of the RLC series resonance circuits is the same with the frequency of the position with the crest. The RLC series resonance circuits can be in cascade connection, so that the problem that a frequency response curve of the front-end circuit has a plurality of crests can be solved; and moreover, the value of direct-current input resistance is not affected.
Description
Technical field
The present invention relates to thermometrically technical field, particularly a kind of oscillograph with frequency response compensation circuit.
Background technology
That conventionally oscillograph input interface adopts is BNC(Bayonet Nut Connector) or the form of compatible BNC, oscillographic input end has common two kinds of input resistance patterns, low-resistance input (being generally 50 Ω or 75 Ω) and high resistant input (being generally 1M Ω).Oscillographic input resistance is an oscillographic important indicator, and oscillograph is connected to after circuit-under-test, and oscillographic input resistance has just become a part for circuit-under-test.Angle from voltage measurement, for little on circuit-under-test impact, oscillograph can adopt the high input resistance of 1M Ω, but, the bandwidth of high impedance circuit is easy to be subject to the impact of stray capacitance, bandwidth is not high, so the input resistance of 1M Ω is widely used in lower than the waveform signal of 500MHZ, measures.For the measurement of higher frequency, carry out impedance matching to measured signal, conventionally adopt low-resistance coupling.Below, with 50 Ω low-resistances, be input as example and describe.50 Ω input resistances are used for and output impedance is that the circuit-under-test of 50 Ω carries out impedance matching, if the two does not mate, signal reflex can occur, and are unfavorable for the realization of high bandwidth.During 50 Ω input resistance, it is very high that oscillographic bandwidth can be done.
With reference to Fig. 1, it is the structural representation of prior art oscillograph 10.Oscillograph 10 comprises BNC input interface 101, input attenuation module 102, input resistance module 103, AFE (analog front end) amplifying circuit module 104, the A/D change-over circuit 105 of series connection successively and controls processing module 106, and be connected on the D/A modular converter 107 of controlling between processing module 106 and AFE (analog front end) amplifying circuit module 104, input resistance module 103 comprises an input resistance 1011, and terminal resistance 1011 one end ground connection, the other end are connected with the input end of AFE (analog front end) amplifying circuit module 104 by a connected node 1012.Input resistance 1011 is terminal build-out resistors of source resistance, and source resistance is the output resistance of circuit-under-test namely.
Measured signal a is accessed by BNC input interface, and inputs to input attenuation module 102 and carry out gain-adjusted; Measured signal after gain-adjusted inputs to AFE (analog front end) amplifying circuit module 104 by input attenuation module 102, by AFE (analog front end) amplifying circuit module 104 amplify, the pre-service such as decay, limit bandwidth, driving; Afterwards, pretreated measured signal inputs to A/D change-over circuit 105, carries out analog-to-digital conversion process, also measured signal is sampled, and obtains digital signal; Finally, digital signal is inputed to control processing module 106 and carry out digital processing, control the data output end output of processing module 106 for the sampled data b of waveform demonstration.In addition, the control output end of controlling processing module 106 also produces a control signal c, in order to control D/A modular converter 107, produces offset signal, and AFE (analog front end) amplifying circuit module 104 is carried out bias treatment according to this offset signal.
As shown in Figure 2 (a) shows, be a kind of structural representation of input attenuation module, attenuator circuit 1013 consists of straight-through decay switching module.When little vertical sensitivity, relay R L1 switches to top direct circuit 1014; During large vertical sensitivity, relay R L1 switches to 50 Ω attenuation module 1015 of below, after measured signal is decayed, exports to 50 Ω input resistances, and wherein, the input resistance of attenuator circuit 1013 is also 50 Ω, for source resistors match.
As shown in Fig. 2 (b), be the schematic diagram of another kind of input attenuation module, attenuator circuit 1013 consists of attenuation network.Attenuation network may be a semi-conductor chip, may be also controlled resistor network.Its input resistance is also 50 Ω, for source resistors match, output also need the terminal resistance that meets 50 Ω to carry out impedance matching.It is 1 that attenuation network can arrange attenuation multiple, can be to be also less than 1, and the multiple of decay is controlled.
In prior art, the frequency response of front end is mainly determined by the frequency response of input attenuation module 102, input resistance module 103 and AFE (analog front end) amplifying circuit module 104.If the frequency response curve of input attenuation module 102, input resistance module 103 or AFE (analog front end) amplifying circuit module 104 is uneven, inconsistent in different frequency place response magnitude, exceed index request, or wished that frequency response curve is more smooth, at this moment just need to carry out compensating for frequency response.
In order to address the above problem, the way of prior art is to increase corrective network between AFE (analog front end) amplifying circuit module 104 and A/D change-over circuit 105, frequency response curve is compensated, to reach the flatness needing, with reference to Fig. 3, for prior art is a kind of, there is the structural representation of the oscillograph 30 of compensating for frequency response circuit.Part in figure before AFE (analog front end) amplifying circuit module 104 is identical with Fig. 1, so not shown.Between the AFE (analog front end) amplifying circuit module 104 of oscillograph 30 and A/D change-over circuit 105, be connected in series with successively RC corrective network 301 and LC corrective network 302, these two corrective networks can exist separately, also can jointly exist.Between the first input end of RC corrective network 301 and the first output terminal, be connected with the RC circuit of R1, C1 parallel connection, between its second input end and the second output terminal, be connected with the RC circuit of R2, C2 parallel connection.Between the first input end of LC corrective network 302 and the first output terminal, be connected with L1, between the second input end and the second output terminal, be connected with L2, the first output terminal and the second output terminal are connected with C3.
The principle of work of RC corrective network 301 is as follows: the input resistance of high-speed a/d change-over circuit 105 is generally smaller, be generally difference 100 Ω, by increasing RC parallel network, when signal frequency is lower, C1, C2 are approximate to open circuit, and signal is through resistance R 1, R2 and A/D change-over circuit 105 internal resistance dividing potential drops; When signal frequency raises gradually, the capacitive reactance of C1, C2 diminishes gradually, the amplitude of A/D change-over circuit 105 input signals is exactly the dividing potential drop of R1, C1, R2, C2 parallel impedance and A/D change-over circuit 105 input resistances, because C1, C2 capacitive reactance diminish, cause R1, C1, R2, C2 parallel impedance to diminish, thereby the signal amplitude of A/D change-over circuit 105 inputs become large.As shown in Figure 4, be the frequency response compensation principle schematic diagram of prior art.The effect increasing after RC corrective network 301 is to raise when measured signal frequency, and the input of A/D change-over circuit 105 increases gradually, makes the front end of frequency response curve toward upwarping.
The principle of work of LC corrective network 302 is as follows: the 104 difference outputs of AFE (analog front end) amplifying circuit module above increase inductance L 1, L2, are connected to two input ends of A/D change-over circuit 105, connect C3 between above-mentioned two input ends simultaneously.Formed LC low-pass network.In conjunction with Fig. 4, when the frequency response curve of AFE (analog front end) amplifying circuit module 104 is when high-frequency ratio is larger, can be by adjusting LC corrective network, while making high frequency, amplitude reduces, and reaches the effect that regulates frequency response curve.
Prior art utilizes RC corrective network 301 and 302 pairs of frequency responses of LC corrective network to regulate, and can make frequency response curve when high frequency, rise and decline, but has following shortcoming:
1, compensating frequency is limited in scope, the frequency response of AFE (analog front end) amplifying circuit often has crest when high frequency, if crest peak value is very large, the amplitude at crest place need to be reduced,, by low pass LC corrective network, very large crest could be decayed to smooth amplitude, but now, LC corrective network also can decay much to the amplitude of frequency lower, inevitably can affect the frequency response curve of part low-frequency range.
Gain when 2, RC corrective network can affect direct current.Because during direct current, the input of A/D change-over circuit 105 has become the dividing potential drop of resistance R 1, R2 and the internal resistance of A/D change-over circuit.
Summary of the invention
Technical matters to be solved by this invention is to provide a kind of oscillograph with frequency response compensation circuit, the gain when affecting the frequency response curve of low-frequency range while avoiding high frequency to carry out compensating for frequency response and avoiding affecting direct current.
In order to solve the problems of the technologies described above, the invention discloses a kind of oscillograph with frequency response compensation circuit, comprise front-end circuit and A/D convertor circuit, described front-end circuit comprises the signal input module being connected in series successively, input resistance module and AFE (analog front end) amplifying circuit module, described oscillograph also comprises at least one RLC series resonant circuit, one end ground connection of described RLC series resonant circuit, the other end is connected to being connected in series on line between signal input module and input resistance module, or be connected to being connected in series on line between input resistance module and AFE (analog front end) amplifying circuit module, frequency response while at least there is crest at a certain frequency place for compensating described front-end circuit, the resonance frequency of described RLC series resonant circuit is identical with the frequency that occurs crest place.
As a kind of, illustrate, between described signal input module and described input resistance module, be also connected in series an input attenuation module, between described signal input module and described input attenuation module, be at least connected a RLC series resonant circuit, described RLC series resonant circuit one end ground connection, the other end is connected to being connected in series on line between signal input module and input attenuation module.
As a kind of, illustrate, between described signal input module and described input resistance module, be also connected in series with an input attenuation module, between described input attenuation module and described input resistance module, be at least connected a RLC series resonant circuit, described RLC series resonant circuit one end ground connection, the other end is connected to being connected in series on line between input attenuation module and input resistance module.
As a kind of, illustrate, between described signal input module and described input resistance module, be also connected in series with an input attenuation module, between input resistance module and AFE (analog front end) amplifying circuit module, be at least connected a RLC series resonant circuit, described RLC series resonant circuit one end ground connection, the other end is connected to being connected in series on line between input resistance module and AFE (analog front end) amplifying circuit.
As a kind of, illustrate, described A/D convertor circuit has the first differential input end and the second differential input end, described AFE (analog front end) amplifying circuit has the first difference output end and the second difference output end, described the first difference output end connects described the first differential input end, described the second difference output end connects described the second differential input end, a RLC series resonant circuit at least in parallel between described the first difference output end and the second difference output end.
As a kind of, illustrate, in described RLC series resonant circuit, the position of resistance, inductance and electric capacity exchanges arbitrarily.
As a kind of, illustrate, the frequency response of described RLC series resonant circuit is identical at the height of the crest at same frequency place with the frequency response of described front-end circuit in the trough degree of depth at resonance frequency place.
In order to solve the problems of the technologies described above, the invention also discloses a kind of oscillograph with frequency response compensation circuit, comprise front-end circuit and A/D convertor circuit, described front-end circuit comprises the signal input module being connected in series successively, input resistance module and AFE (analog front end) amplifying circuit module, described A/D convertor circuit has the first differential input end and the second differential input end, described AFE (analog front end) amplifying circuit has the first difference output end and the second difference output end, described the first difference output end connects described the first differential input end, described the second difference output end connects described the second differential input end, a RLC series resonant circuit at least in parallel between described the first difference output end and the second difference output end, frequency response while at least there is crest at a certain frequency place for compensating described front-end circuit, the resonance frequency of described RLC series resonant circuit is identical with the frequency that occurs crest place.
The present invention according to the frequency response of front-end circuit in the frequency that occurs crest place, determine the resonance frequency of described RLC series resonant circuit, by the value of control capacittance and inductance, determine this resonant frequency value, because the frequency response curve of RLC series resonant circuit at resonance frequency place presents trough shape, so the crest at same frequency place in the frequency response of front-end circuit has been played to the effect of compensation.Regulate resistance, inductance and the capacitance of RLC series circuit can determine the Q value of RLC series network simultaneously, and the size of Q value has determined the degree of depth of RLC series resonant circuit at the trough of the frequency response curve at resonance frequency place, adjust Q value, make RLC series resonant circuit identical at the height of the crest of the degree of depth of the trough of the frequency response curve at resonance frequency place and the frequency response of front-end circuit, can arrive the effect of the crest of the frequency response of eliminating front-end circuit.
The trough of RLC series circuit is corresponding with the crest of the frequency response curve of front-end circuit, during to high-frequency compensation, does not affect relatively low frequency range, does not affect DC current gain.The present invention can use the cascade of a plurality of RLC series resonant circuit, can solve the situation that occurs several crests in front-end circuit frequency response curve.In addition, the present invention has reduced the designing requirement to circuit, and circuit is simple, cost is low.Owing to adopting RLC series resonant circuit to compensate, DC current is without RLC series resonant circuit, so do not affect the size of direct current input resistance simultaneously.
Accompanying drawing explanation
Fig. 1 is the structural representation of prior art oscillograph 10
Fig. 2 is the structural representation of input attenuation module 102 in Fig. 1
Fig. 3 is the structural representation that prior art has the oscillograph 30 of frequency response compensation circuit
Fig. 4 is the frequency response compensation principle schematic diagram of prior art
Fig. 5 is the structural representation that the preferred embodiment of the present invention 1 has the oscillograph 50 of frequency response compensation circuit
Fig. 6 is the schematic diagram of the frequency response curve Y of RLC series resonant circuit of the present invention
Fig. 7 is preferred embodiment of the present invention frequency response compensation schematic diagram
Fig. 8 is the structural representation that the preferred embodiment of the present invention 2 has the oscillograph 60 of frequency response compensation circuit
Fig. 9 is the schematic diagram that a plurality of crests appear in front-end circuit frequency response
Figure 10 is the structural representation that the preferred embodiment of the present invention 3 has the oscillograph 70 of frequency response compensation circuit
Figure 11 is the structural representation that the preferred embodiment of the present invention 4 has the oscillograph 80 of frequency response compensation circuit
Figure 12 is the structural representation that the preferred embodiment of the present invention 5 has the oscillograph 90 of frequency response compensation circuit
Figure 13 is the structural representation that the preferred embodiment of the present invention 6 has the oscillograph 100 of frequency response compensation circuit
Embodiment
Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.
Preferred embodiment 1: with reference to Fig. 5, it is the structural representation with the oscillograph 50 of frequency response compensation circuit, comprise front-end circuit 501 and A/D convertor circuit 502, front-end circuit 501 comprises the signal input module 5011 being connected in series successively, input resistance module 5012 and AFE (analog front end) amplifying circuit module 5013, signal input module 5011 specifically refers to oscillograph input interface, that this preferred embodiment adopts is BNC(Bayonet Nut Connector) input interface, in this preferred embodiment, input resistance module 5012 is selected 50 Ω input resistances, described 50 Ω input resistance one end ground connection, one end is connected to series connection input end and the series connection output terminal of input resistance module, described oscillograph 50 also comprises controls processing module and D/A modular converter, signal input module 5011 receives external input signal, the amplification that described AFE (analog front end) amplifying circuit module 5013 completes external input signal, decay, after limit bandwidth and ADC drive, input to A/D convertor circuit 502 and carry out analog to digital conversion, data after conversion are sent into control processing module and are processed, AFE (analog front end) amplifying circuit module 5013 is also inputted offset signal simultaneously, controlling processing module control D/A modular converter regulates described offset signal.Described oscillograph 50 also comprises a RLC series resonant circuit 5014, one end ground connection of RLC series resonant circuit 5014, the other end is connected to being connected in series on line between signal input module 5011 and input resistance module 5012, frequency response while there is crest for compensating described front-end circuit 501 at a certain frequency f 0 place, the resonance frequency of described RLC series resonant circuit 5014 is identical with the f0 frequency that occurs crest place.Resonance frequency is exactly the frequency at trough place at the frequency response curve of RLC series resonant circuit 5014.Because the frequency response curve of RLC series resonant circuit 5014 at resonance frequency place presents trough shape, so the crest at same frequency place in the frequency response of front-end circuit has been played to the effect of compensation.
In the RLC series resonant circuit being comprised of resistance R, inductance L, capacitor C, inductance L and capacitor C are determined tuning-points frequency, make this frequency consistent with former front-end circuit frequency response curve peak frequencies; Resistance R, inductance L and capacitor C are determined the quality factor q value of RLC series resonant circuit, and Q value is larger, and the trough of frequency response curve is sharper, and frequency band is narrower, and frequency selectivity is better, more can compensate the former front-end circuit frequency response curve that crest is larger.
If the capacitive reactance of capacitor C is X
c=1/(2 π fC), the induction reactance of inductance L is X
l=2 π fL, work as X
c=X
ltime, RLC series resonant circuit 5014 produces resonance, and energy is back and forth exchange between inductance L and capacitor C.Resonance frequency now
The impedance of RLC series resonant circuit 5014 is minimum and be pure resistive, and resistance is R, quality factor
With reference to Fig. 5, while supposing not have RLC series resonant circuit 5014, former front-end circuit frequency response curve has the crest of 6dB when fO=1GHz.Can determine by following scheme the value of R1, L1, C1.First short-circuit resistance R1, thus Q value is infinitely great, and now the selecting frequency characteristic of RLC series resonant circuit 5014 is very good, according near resonance frequency f this condition 1GHz, can obtain the product of L1 and C1.In addition, except the computing formula of resonance frequency f, it is also conceivable that the factor from other: owing to improving Q value, can need Q larger so that its frequency response curve is sharper, therefore select L1 larger, C1 be smaller; Also according to the precision that now C1, L1 can reach, select C1, L1 value simultaneously, for example, can select C1=4pF, L1=5.6nH, now resonance frequency is 1.04GHz.Now can reach the effect of the former front-end circuit frequency response curve crest of compensation, in order to reach more perfect compensation effect, after C1 and L1 determine, select again different R1 values, to adjust Q value, make RLC series resonant circuit identical at the height of the crest of the degree of depth of the trough of the frequency response curve at resonance frequency place and the frequency response of front-end circuit, can arrive the effect of the crest of the frequency response of eliminating front-end circuit.Make to add that frequency response curve after RLC series resonant circuit 5014 is at 1GHz substantially flat, concrete way is according to software emulation or experiment, adjust different R1 values, make to add that the frequency response at 1GHz place of frequency response curve after RLC series resonant circuit 5014 approximates 0dB, so far the value of R1, L1, C1 is determined, for example, can select R1=100 Ω.
With reference to Fig. 6, it is the schematic diagram of the frequency response curve Y of RLC series resonant circuit.Former frequency response curve has a very large crest at fO place, increase RLC series resonant circuit, makes its resonance frequency equal fO, the crest of former frequency response curve has been played to the effect of compensation.With reference to Fig. 7, it is frequency response compensation schematic diagram.When selecting suitable Q value, the trough degree of depth of this frequency response curve Y and the crest height of former frequency response curve are basically identical, and the curve after stack will be more smooth like this.Curve X is the former frequency response curve that there is no compensating for frequency response circuit, and curve Y is the frequency response curve of RLC series resonant circuit, and curve Z is for increasing the frequency response curve after RLC series resonant circuit.
In RLC series resonant circuit 5014, the position of R1, L1, C1 can exchange, and example is one end ground connection of C1 as shown in Figure 5, also can make one end ground connection of R1 or L1.
Preferred embodiment 2: with reference to Fig. 8, be the structural representation that the present invention has the oscillograph 60 of frequency response compensation circuit.Comprise front-end circuit 601 and A/D convertor circuit 502, front-end circuit 601 comprises the signal input module 5011 being connected in series successively, input attenuation module 6011, input resistance module 5012 and AFE (analog front end) amplifying circuit module 5013, signal input module 5011 specifically refers to oscillograph input interface, that this preferred embodiment adopts is BNC(Bayonet Nut Connector) input interface, in this preferred embodiment, input resistance module 5012 is selected 50 Ω input resistances, described 50 Ω input resistance one end ground connection, one end is connected to series connection input end and the series connection output terminal of input resistance module, described oscillograph 50 also comprises a RLC series resonant circuit 5014, one end ground connection of RLC series resonant circuit 5014, the other end is connected to being connected in series on line between signal input module 5011 and input attenuation module 6011, frequency response while there is crest for compensating described front-end circuit 501 at a certain frequency f 0 place, the resonance frequency of described RLC series resonant circuit 5014 is identical with the f0 frequency that occurs crest place.Resonance frequency is exactly the frequency at trough place at the frequency response curve of RLC series resonant circuit 5014.Because the frequency response curve of RLC series resonant circuit 5014 at resonance frequency place presents trough shape, so the crest at same frequency place in the frequency response of front-end circuit has been played to the effect of compensation.
Preferred embodiment 3: with reference to Fig. 9, when there is a plurality of crest in front-end circuit frequency response, for example, while there is two crests, with reference to Figure 10, the oscillograph 70 of this preferred embodiment increases one-level the 2nd RLC series resonant circuit 7011 on the basis of preferred embodiment 2, and resonance frequency and respectively corresponding two frequencies that crest is corresponding of the 2nd RLC series resonant circuit 7011 of RLC series resonant circuit 5014 are set respectively.The sequencing of two-stage series connection resonant circuit does not require.When former front-end circuit frequency response has a plurality of crest, can a plurality of RLC corrective networks of corresponding increase.
Preferred embodiment 4: with reference to Figure 11, it is the structural representation that the present invention has the oscillograph 80 of frequency response compensation circuit, by RLC series resonant circuit 5014 one end ground connection, the other end is connected to being connected in series on line between input attenuation module 6011 and input resistance module 5012, also plays the effect of front-end circuit frequency response curve being played to compensation.
Preferred embodiment 5: with reference to Figure 12, it is the structural representation that the present invention has the oscillograph 90 of frequency response compensation circuit, with the difference of preferred embodiment 2 be, input attenuation module 9011 is gain modules, this gain module input resistance is 50 Ω, and it is 1 that gain can be selected in inside, also can select gain to be less than 1, output resistance is 50 Ω, is connected to input resistance module 5012 and mates.Above-mentioned output resistance refers to the output resistance of 50 Ω gain modules, from output terminal, sees into the equivalent resistance of 50 Ω gain modules.Gain module can be selected digital pad, and as PE4302, realization-0.5dB is to the decay of-31.5dB.Also can select other similar chip gains.
Similar with preferred embodiment 4, when input attenuation module 9011 is a gain module, RLC series resonant circuit 5014 also can one end ground connection, the other end is connected to being connected in series on line between input attenuation module 9011 and input resistance module 5012, and front-end circuit frequency response curve is compensated.
Preferred embodiment 6: with reference to Figure 13, be the structural representation that the present invention has the oscillograph 100 of frequency response compensation circuit.Oscillograph 100 comprises front-end circuit 1001, A/D change-over circuit 502, controls processing module and D/A modular converter.Front-end circuit 1001 comprises signal input module 5011, input attenuation module 9011, input resistance module 5012 and the AFE (analog front end) amplifying circuit module 5013 of series connection successively.AFE (analog front end) amplifying circuit module 5013 has the first difference output end 10012 and the second difference output end 10013, A/D convertor circuit 502 has the first differential input end 10014 and the second differential input end 10015, the first difference output end 10012 connects described the first differential input end 10014, the second difference output end 10013 connects described the second differential input end 10015, a RLC series resonant circuit 5014 in parallel between described the first difference output end 10012 and the second difference output end 10013, also be, one end of described RLC series resonant circuit 5014 connects the first difference output end 10012, the other end connects the second difference output end 10013, frequency response while at least there is crest at a certain frequency place for compensating described front-end circuit, the resonance frequency of described RLC series resonant circuit is identical with the frequency that occurs crest place.Further, can adjust again Q value, make RLC series resonant circuit identical at the height of the crest of the degree of depth of the trough of the frequency response curve at resonance frequency place and the frequency response of front-end circuit, can arrive the effect of the crest of the frequency response of eliminating front-end circuit.
As an example, in front-end circuit 1001, can there is no input attenuation module 9011 yet.
As an example, when there is a plurality of crest in front-end circuit frequency response curve, correspondingly can be between the first difference output end 10012 and the second difference output end 10013 a plurality of RLC series resonant circuits in parallel.
As an example, R, the L in RLC series resonant circuit, C can transpositions.
As an example, input resistance can be the input resistance of 75 Ω.
Inventor at one in first to file, used R, L, C resonant circuit parallel with one another to compensate there is the frequency response of crest in front-end circuit, inventor is after scrutinizing, determine improvement technical scheme of the present invention, adopted RLC series resonant circuit to compensate there is the frequency response of crest in front-end circuit.
New departure is as follows with respect to the beneficial effect of such scheme: take preferred embodiment 2 as example, adopt R, L, C compensation scheme parallel with one another, the size of input resistance in the time of can affecting direct current, because during direct current, input signal is through L and 50 Ω input resistances, high Q inductance, general is all wire-wounds, itself there is certain direct current resistance, be generally less than 1 Ω, so can affect input resistance size.And adopting RLC series resonant circuit to compensate, DC current is without RLC series circuit, on not impact of input resistance.When for differential signal, take preferred embodiment 6 as example, while adopting R, L, C compensation scheme parallel with one another, need for the differential signal Rop of the first difference output end 10012 outputs and the differential signal Ron of the second difference output end 10013 outputs, to use two groups of R, L, C parallel circuit respectively, device is many, and circuit is complicated.And because the value of L and C is all smaller, itself has certain error device, guarantee that like this RLC on differential signal Rop and differential signal Ron is in full accord more difficult, can not guarantee the same resonance frequency and Q value, just can not guarantee differential signal Rop to produce the same effect with differential signal Ron, cause the differential signal of A/D convertor circuit input near resonance frequency, to have fluctuating.And adopt RLC series resonant circuit to compensate, do not have above-mentioned shortcoming, RLC series resonant circuit acts between differential signal Rop and differential signal Ron.
Above-described is only the preferred embodiments of the present invention; institute is understood that; the explanation of above preferred embodiment is just for helping to understand method of the present invention and core concept thereof; the protection domain being not intended to limit the present invention; all any modifications of making, be equal to replacement etc., within protection scope of the present invention all should be included within thought of the present invention and principle.
Claims (8)
1. an oscillograph with frequency response compensation circuit, comprise front-end circuit and A/D convertor circuit, described front-end circuit comprises the signal input module being connected in series successively, input resistance module and AFE (analog front end) amplifying circuit module, it is characterized in that, described oscillograph also comprises at least one RLC series resonant circuit, one end ground connection of described RLC series resonant circuit, the other end is connected to being connected in series on line between signal input module and input resistance module, or the other end is connected to being connected in series on line between input resistance module and AFE (analog front end) amplifying circuit module, frequency response while at least there is crest at a certain frequency place for compensating described front-end circuit, the resonance frequency of described RLC series resonant circuit is identical with the frequency that occurs crest place.
2. oscillograph according to claim 1, it is characterized in that, between described signal input module and described input resistance module, be also connected in series an input attenuation module, between described signal input module and described input attenuation module, be at least connected a RLC series resonant circuit, described RLC series resonant circuit one end ground connection, the other end is connected to being connected in series on line between signal input module and input attenuation module.
3. oscillograph according to claim 1, it is characterized in that, between described signal input module and described input resistance module, be also connected in series with an input attenuation module, between described input attenuation module and described input resistance module, be at least connected a RLC series resonant circuit, described RLC series resonant circuit one end ground connection, the other end is connected to being connected in series on line between input attenuation module and input resistance module.
4. oscillograph according to claim 1, it is characterized in that, between described signal input module and described input resistance module, be also connected in series with an input attenuation module, between input resistance module and AFE (analog front end) amplifying circuit module, be at least connected a RLC series resonant circuit, described RLC series resonant circuit one end ground connection, the other end is connected to being connected in series on line between input resistance module and AFE (analog front end) amplifying circuit.
5. according to the oscillograph described in claim 1,2,3 or 4, it is characterized in that, described A/D convertor circuit has the first differential input end and the second differential input end, described AFE (analog front end) amplifying circuit has the first difference output end and the second difference output end, described the first difference output end connects described the first differential input end, described the second difference output end connects described the second differential input end, a RLC series resonant circuit at least in parallel between described the first difference output end and the second difference output end.
6. oscillograph according to claim 5, is characterized in that, in described RLC series resonant circuit, the position of resistance, inductance and electric capacity exchanges arbitrarily.
7. oscillograph according to claim 6, is characterized in that, the frequency response of described RLC series resonant circuit is identical at the height of the crest at same frequency place with the frequency response of described front-end circuit in the trough degree of depth at resonance frequency place.
8. an oscillograph with frequency response compensation circuit, comprise front-end circuit and A/D convertor circuit, described front-end circuit comprises the signal input module being connected in series successively, input resistance module and AFE (analog front end) amplifying circuit module, it is characterized in that, described A/D convertor circuit has the first differential input end and the second differential input end, described AFE (analog front end) amplifying circuit has the first difference output end and the second difference output end, described the first difference output end connects described the first differential input end, described the second difference output end connects described the second differential input end, a RLC series resonant circuit at least in parallel between described the first difference output end and the second difference output end, frequency response while at least there is crest at a certain frequency place for compensating described front-end circuit, the resonance frequency of described RLC series resonant circuit is identical with the frequency that occurs crest place.
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| CN104267228A (en) * | 2014-09-30 | 2015-01-07 | 中国电子科技集团公司第四十一研究所 | Circuit allowing trigger sensitivity of digital oscilloscope to be continuously adjustable |
| CN104917477A (en) * | 2015-06-02 | 2015-09-16 | 青岛海信电器股份有限公司 | Filter |
| CN106329896A (en) * | 2015-06-18 | 2017-01-11 | 鸿富锦精密工业(武汉)有限公司 | DC power supply circuit |
| CN112865746A (en) * | 2021-01-26 | 2021-05-28 | 河南省洛阳正骨医院（河南省骨科医院） | Frequency response compensation circuit for electrocardiograph |
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Application publication date: 20140129 |