A kind of sinusoidal reference circuit
[technical field]
The present invention relates to a kind of sinusoidal signal generator, relate in particular to a kind of output voltage and independent adjustable sinusoidal reference circuit of frequency that is applied to the ringing-current module.
[background technology]
The ringing current power source module is a kind of small-power DC/AC inverter, is used in communication system and the sonar system more.The ringing-current inside modules needs a sine signal source, usually adopt simple and waveform quality preferably Wien bridge circuit produce a frequency and the fixing sinusoidal signal of amplitude, be used to control the output of ringing-current module, its traditional sinusoidal signal generation circuit based on Wien bridge circuit as shown in Figure 1, in the drawings, reference voltage V ref is connected with the input of pi regulator by one or more resistance, reference signal as pi regulator, pi regulator and Wien bridge circuit interconnect, the output of Wien bridge circuit can produce a sinusoidal signal, in order to stablize this sinusoidal signal amplitude, between the input of the output of Wien bridge circuit and pi regulator, be provided with a feedback loop, this feedback loop is by resistance R 1, diode D1, capacitor C 1 is formed, diode D1 offset of sinusoidal signal carries out rectification, carry out filtering by capacitor C 1, obtaining a DC component is added on the input of pi regulator, pi regulator compares reference signal and DC component, produce an error signal, Wien bridge circuit is according to its output signal of the corresponding adjusting of this error signal.The frequency of oscillation of the sinusoidal signal of Wien bridge circuit output is decided by the impedance of RC series shunt network, and the RC series shunt network comprises resistance R 51 and R52, capacitor C 51 and C52.When positive feedback coefficient during greater than degeneration factor, the automatic starting of oscillation of Wien bridge circuit, and amplitude increases, otherwise amplitude reduces.Just carry out fixed ampllitude (stablizing amplitude) in this circuit by changing degeneration factor offset of sinusoidal output.
Constantly expand owing to use the region of ringing-current module, just be faced with each countries and regions the diversification difference on ringing-current module output voltage and the frequency needs.The frequency of oscillation of Wien bridge circuit is by the decision of the resistance value of RC series-parallel network, can realize adjusting to output frequency by regulating this impedance.If use traditional Wien bridge circuit shown in Figure 1 to carry out frequency modulation output, its amplitude changes greatly when frequency of oscillation changes, only rely on the fixed ampllitude link (feedback loop) of Wien bridge circuit self can't export constant amplitude, this is because the half-wave peak value that conventional feedback adopts detects, though its device seldom circuit is simple, but it has bigger non-linear, and output frequency can't reflect correctly when changing that the output sinusoidal magnitude value changes, thereby output amplitude changes greatly.Though the precision of voltage regulation is necessarily improved by revising circuit parameter, bring output to stablize elongated problem of required time, be greatly limited in actual applications.In other words, the output signal frequency of traditional Wien bridge circuit and amplitude mutual interference mutually can not independent regulation, can't realize the variation of output signal frequency and amplitude.
[summary of the invention]
The technical problem to be solved in the present invention provides a kind of sinusoidal reference circuit, when having increased frequency modulation function, solved the change in voltage problem that causes because of frequency modulation, can make sinusoidal reference circuit output signal frequency and amplitude independent adjustable, thereby the frequency and the amplitude of the output voltage of realization ringing-current module are independent adjustable, do not disturb mutually.
The present invention realizes by following technical scheme:
A kind of sinusoidal reference circuit, comprise error adjuster, Wien bridge circuit and testing circuit, described testing circuit detects the output signal of Wien bridge circuit, and feed back to the input of error adjuster, error adjuster benchmark signal and described output signal, obtain an error signal, Wien bridge circuit is according to its output signal of the corresponding adjustment of this error signal;
The resistance value scalable of RC series shunt network in the described Wien bridge circuit;
Described testing circuit comprises a full-wave rectifying circuit.
Further improvement of the present invention is:
Resistance in the described RC series shunt network is variable resistor or the optional resistance unit of resistance, and/or electric capacity is that variable capacitance or appearance are worth optional capacitor cell.
Further improvement of the present invention is:
Described full-wave rectifying circuit comprises first resistance, second resistance, first operational amplifier and first diode; One end of described first resistance links to each other with the output of described Wien bridge circuit, its other end links to each other with the reverse input end of described first operational amplifier, the positive input ground connection of described first operational amplifier, its output links to each other with an end of second resistance by first diode, the input of this tie point and error adjuster is coupled, and the other end of described second resistance connects the reverse input end of described first operational amplifier.
Further improvement of the present invention is:
Described testing circuit also comprises a filter circuit, and described filter circuit comprises first electric capacity and the 3rd resistance; One end of described the 3rd resistance links to each other with the tie point of second resistance with described first diode, and its other end is coupled by first capacity earth and with the input of error adjuster.
Further improvement of the present invention is:
Described testing circuit also comprises second operational amplifier, the tie point of described first electric capacity and the 3rd resistance connects the positive input of second operational amplifier, the reverse input end of second operational amplifier is connected with its output, and the input of this tie point and error adjuster is coupled.
Further improvement of the present invention is:
Described error adjuster can be a proportional and integral controller.
Further improvement of the present invention is:
Also comprise an adjustable reference, described adjustable reference can be regulated the amplitude of sine output signal.
Further improvement of the present invention is:
Described reference circuit comprises first variable resistor, the 4th resistance, the 5th resistance, voltage-reference and DC source, described DC source is successively by the 4th resistance, the pin 1 of voltage-reference, pin 3 ground connection, the pin 2 of voltage-reference is by the first variable resistor ground connection, described the 5th resistance is connected between the pin 1 and pin 2 of voltage-reference, and the pin 1 of described voltage-reference is connected with the input of error adjuster.
Owing to adopt above technical scheme, make sinusoidal reference circuit output signal frequency and amplitude independent adjustable, do not disturb mutually, realize frequency adjustment by the resistance value that changes RC series shunt network in the Wien bridge circuit on the one hand, keep the amplitude substantially constant simultaneously; Realize the amplitude adjusting by the given voltage of fixed ampllitude control ring direct current amplitude (reference voltage) that changes Wien bridge circuit on the other hand, output frequency is unaffected simultaneously; Especially when the frequency wide variation, its output stabilized voltage characteristic is fine, when output frequency when 15Hz~60Hz changes, the output voltage regulation that causes because of frequency has satisfied the voltage stabilizing requirement well less than 1%.
[description of drawings]
Fig. 1 is traditional sinusoidal signal generation circuit schematic diagram based on Wien bridge circuit.
Fig. 2 is a structured flowchart of the present invention.
Fig. 3 is circuit theory diagrams of the present invention (one).
Fig. 4 is the connection diagram () of resistor network in the RC series shunt network of the present invention.
Fig. 5 is the connection diagram (two) of resistor network in the RC series shunt network of the present invention.
Fig. 6 is the connection diagram of capacitance network in the RC series shunt network of the present invention.
Fig. 7 is the connection diagram of RC series shunt network of the present invention.
Fig. 8 is circuit theory diagrams of the present invention (two).
Fig. 9 is circuit theory diagrams of the present invention (three).
Figure 10 is circuit theory diagrams of the present invention (four).
Figure 11 is the another kind of full-wave rectifying circuit schematic diagram in the testing circuit of the present invention.
[embodiment]
Below in conjunction with drawings and Examples the present invention is further set forth:
As shown in Figure 2, sinusoidal reference circuit of the present invention comprises reference circuit, error adjuster, Wien bridge circuit and testing circuit, reference circuit is used to provide a reference voltage signal, its input with the error adjuster links to each other, the output of error adjuster links to each other with the input of Wien bridge circuit, and testing circuit is connected between the input of the output of Wien bridge circuit and error adjuster; Testing circuit detects the output signal of Wien bridge circuit, and the input of this signal feedback to the error adjuster, the error adjuster compares this signal and reference voltage signal, obtains an error signal, exports to Wien bridge circuit, its output signal of corresponding adjusting.
In the present invention, the error adjuster is a pi regulator, it is to be noted that the error adjuster of other type also is feasible.
As shown in Figure 3, be circuit theory diagrams of the present invention.The output of pi regulator and the input of Wien bridge circuit interconnect, and pi regulator comprises the 3rd operational amplifier N3, and the output of the 3rd operational amplifier N3 is the output of pi regulator.
Comprise rectification circuit in the testing circuit, filter circuit, the second operational amplifier N2, wherein, rectification circuit comprises first resistance R 1, second resistance R 2, the first operational amplifier N1 and the first diode D1, filter circuit comprises first capacitor C 1 and the 3rd resistance R 3, one end of described first resistance R 1 links to each other with the output of described Wien bridge circuit, its other end links to each other with the reverse input end of the described first operational amplifier N1, the positive input ground connection of the described first operational amplifier N1, its output passes through the negative electrode of the first diode D1 successively, anode links to each other with an end of second resistance R 2, and the other end of described second resistance R 2 connects the reverse input end of the described first operational amplifier N1; One end of described the 3rd resistance R 3 links to each other with the described first diode D1 anode, its other end also links to each other with the positive input of the second operational amplifier N2 by first capacitor C, 1 ground connection, this end, the reverse input end of the second operational amplifier N2 is connected with its output, and the positive input of the 3rd operational amplifier N3 is coupled in the output of the second operational amplifier N2 and the pi regulator.
Reference circuit comprises the first variable resistor RX, the 4th resistance R 4, the 5th resistance R 5, voltage-reference U1 and DC source, wherein, DC source is 5V, described DC source is successively by the 4th resistance R 4, the pin 1 of voltage-reference U1, pin 3 ground connection, the pin 2 of voltage-reference U1 is by the first variable resistor RX ground connection, described the 5th resistance R 5 is connected between the pin 1 and pin 2 of voltage-reference U1, and the positive input of the 3rd operational amplifier N3 is coupled in the pin 1 of described voltage-reference U1 and the pi regulator.The maximum output voltage of this reference circuit is a reference voltage, and in order to reduce output impedance, the rear end need connect the circuit of high input impedance usually, as connects the amplifier follower, or the error adjuster of high input impedance.
In Wien bridge circuit, the RC series shunt network comprises the tenth capacitor C
AB, the 11 capacitor C
BC, the tenth resistance R
ABWith the 11 resistance R
BC, the tenth capacitor C
ABWith the tenth resistance R
ABBe connected in parallel the 11 capacitor C
BC, and the 11 resistance R
BCBe connected in series.The tenth capacitor C
ABWith the 11 capacitor C
BCCapacitance can be definite value, perhaps capacitance adjustable (electric capacity is that variable capacitance or appearance are worth optional capacitor cell), the tenth resistance R
ABWith the 11 resistance R
BCResistance value can be definite value, perhaps resistance value adjustable (resistance is variable resistor or the optional resistance unit of resistance), but the value of these four components and parts must have at least one can regulate, the resistance value that could guarantee the RC series shunt network is variable, and then can regulate the output signal frequency of Wien bridge circuit.Among the present invention, capacitance hypothesis is constant, the resistance value of a synchronous change and capacitances in series or parallel resistor, the type of attachment of resistor network as shown in Figure 4 and Figure 5, in Fig. 4, the tenth resistance R
ABWith the 11 resistance R
BCAll adopt the optional resistance unit of resistance, realize adjusting resistance value by the multiway analog switch selection path, and in Fig. 5 the tenth resistance R
ABWith the 11 resistance R
BCAll adopt variable resistor to realize, simultaneously, resistor network can be in the inside of Wien bridge circuit, also can be in the outside of Wien bridge circuit, and dotted line shown in Figure 4 top is Wien bridge circuit inside, dotted line shown in Figure 5 bottom is the Wien bridge circuit outside.
In addition, when electric capacity adopted appearance to be worth optional capacitor cell, circuit diagram was referring to Fig. 6; When resistance adopts variable resistor, and electric capacity is when also adopting variable capacitance, and circuit diagram is referring to Fig. 7.
In the testing circuit, by first resistance R 1, second resistance R 2, the first operational amplifier N1 and the first diode D1 form simple full-wave rectifying circuit, the use device is few, eliminated the influence that the diode current flow pressure drop detects amplitude, and carry out filtering by the 3rd resistance R 3 and first capacitor C 1, obtain the DC component after the rectification, relative halfwave rectifier and half-wave peak detection circuit, the linearity is better between detected DC component and the actual output sinusoidal magnitude value, the difference of filter circuit amplitude-frequency response when having reduced frequency change, the amplitude of offset of sinusoidal benchmark accurately detects to greatest extent, guarantees the amplitude stability that output is sinusoidal.The second operational amplifier N2 carries out impedance matching, helps the design and the debugging of parameter.
In order to reduce the number of device, also can save the second operational amplifier N2 in some occasion among Fig. 3, its circuit theory diagrams are referring to Fig. 8, and amplitude detects and is the negative sense full-wave rectification.
As shown in Figure 9, be another circuit theory diagrams of the present invention, the difference of this circuit diagram and Fig. 3 is: the connection of the first diode D1 is different, and reference circuit connects the positive input of the 3rd operational amplifier N3.The anode of the first diode D1 is connected with the output of the described first operational amplifier N1, and the reverse input end of its negative electrode and described the 3rd operational amplifier N3 is coupled; Amplitude detects and is the forward full-wave rectification.Here also can save the second operational amplifier N2, its circuit theory diagrams are referring to Figure 10, and amplitude detects and is the forward full-wave rectification.
In addition, full-wave rectifying circuit of the present invention can also be a circuit as shown in figure 11, Ui is the input signal of this full-wave rectification, Uo is the output signal of this full-wave rectification, the advantage of this circuit be can be on resistance R 5 filter capacitor in parallel, can regulate gain by change R5, gain can be greater than 1, also can be less than 1.It is R1=R4 that resistors match is closed, and R4=R5=2R3 fully can be with 6 substitutional resistance R realizations, and wherein resistance R 3 can be with two R parallel connections.
In sum, the present invention adopts full-wave rectification that output amplitude is detected and filtering, because through full-wave rectification, the frequency of detected signal is the twice (with respect to halfwave rectifier and half-wave peak detection circuit) of original signal, just can detect the sinusoidal amplitude of output more exactly by less filtering parameter, make and also can reflect the variation of exporting sinusoidal magnitude value more accurately when frequency of oscillation changes in a big way, thereby the purpose of fixed ampllitude when reaching frequency conversion, the stable time of output is shortened greatly, satisfy requirement of actual application.
The present invention can realize that the amplitude of offset of sinusoidal reference circuit output signal and frequency carry out independent regulation, be independent of each other, particularly adopted full-wave rectifying circuit in the testing circuit, eliminated the influence that the diode current flow pressure drop detects amplitude, guarantee the amplitude stability of Wien bridge circuit output signal, promptly obtain accurately amplitude and feed back, the amplitude stability when realizing different frequency by full-wave rectification and filtering; Realize the frequency selection by regulating the impedance of Wien bridge circuit RC series shunt network, but the impedance flexible of RC series shunt network is easy to operate, has satisfied the requirement of Wien bridge circuit output signal frequency diversification.