Instrumentation amplifier with controlled frequency response parameters. RU patent 2519429.

FIELD: machine building.

SUBSTANCE: instrumentation amplifier with controlled frequency response parameters comprises a signal source, an input differential stage, balancing capacitors, power supply buses, current outputs of the input differential stage, current-stabilising two-terminal elements, a current mirror and an emitter.

EFFECT: high attenuation of the output signal in the low frequency range with a high and sufficiently stable Q factor of the frequency response of the instrumentation amplifier and high voltage gain at quasi-resonance frequency f₀.

3 cl, 10 dwg

The present invention relates to the field of measuring equipment, radio engineering and communication and can be used in filtering devices radio, television, radar, including for the purposes of measurement of parameters of high-frequency signals, etc.

In problems of measurement of parameters and selection of high-frequency signals are now widely used integrated operational amplifiers with special elements RC-correction form of amplitude-frequency characteristic of resonant type [1, 2]. However, the classical construction of such instrumentation amplifiers (in-amps) is accompanied by significant energy losses, which go mainly to ensure static conditions of a sufficiently large number of minor transistors, forming operational amplifier [1, 2]. In this regard, it is highly important task of building Yiwu at the lowest possible number of transistors that provide allocation of narrow-spectrum signals with high quality factor (Q) resonance parameters (Q=2 to 10) with low power consumption.

Known schemes Yiwu, integrated into the architecture RC-filters based on bipolar transistors, ensuring the formation of amplitude-frequency characteristic gain voltage within the specified range of frequencies F=f-f n [3-10]. And their upper cutoff frequency f in sometimes is generated by the inertia of transistor circuits (capacity on a substrate), and the lower f n is determined by special correction capacitor.

The closest prototype of the proposed device is power, represented in the patent US 4843343 fig.2. It contains the signal source 1, attached to the first input 2 input differential cascade 3, the first 4 correction capacitor AC between output 5 and common bus power supply 6, with the second input 7 input differential cascade 3 is associated with the exit device 5, the first 8 and 9 second current output input differential cascade 3, the first 10 ecostability dvuhgolosyj included between the first 11 bus power supply and input 12 current mirrors 13, 14 second ecostability dvuhgolosyj included between 15 current mirrors 13 and the first 11 bus power supply, the second 16 correction capacitor, the second 17 bus power supply, consistent with the emitter circuit input differential cascade 3.

Significant shortcomings Yiwu-prototype figure 1 are the following:

- to provide great (K y =10 -3% to 10 -4 ) attenuation output

signal in the range of low frequencies (f<<f 0 ) in the structure of Yiwu figure 1, you must use a connecting a signal source 1 to the first 2 input transistor through a special input coupling capacitor, whose capacity should be significantly larger vessels the frequency-specifies the chain (the first 11 and 13 second correction capacitors). In addition, in this case, the necessary additional Ragimzade resistor base circuit of the input transistor 2;

- for cascading (serial connection) of such schemes in Yiwu bandpass filters must use an additional buffer amplifiers;

- in the structure figure 1 problematic to obtain high dobroteasa. When implementing large dobroteasa (Q=3...10) it is necessary to use a large value of resistance ecostability of dvuhyarusnaya 10, which increases the proportional impact on the work scheme of parasitic capacitance collector junction transistor 3 and output capacitance current mirrors. Ultimately, this limits the range of operating frequencies Yiwu-prototype.

The main objective of the invention is to increase the damping of the output signal in the range of low frequencies at high and stable enough quality factor Q amplitude-frequency characteristics (AFC) of Yiwu and big factor gain voltage (K 0 ) at the frequency of quasiresonant f 0 .

The problem is solved by the fact that in the measuring amplifier figure 1 that contains the signal source 1, connected to the first input 2 input differential cascade 3, the first 4 correction capacitor AC between output 5 and common bus power supply 6, with the second input 7 input differential cascade 3 is associated with the exit device 5, the first 8 and 9 second current output input differential cascade 3, the first 10 ecostability dvuhgolosyj included between the first 11 bus power supply and input 12 current mirrors 13, 14 second ecostability dvuhgolosyj included between 15 current mirrors 13 and the first 11 bus power supply, the second 16 correction capacitor, the second 17 bus power supply, consistent with the emitter circuit input differential cascade 3, there are new elements and communications - 16 second correction capacitor connected between the output of the 15 current mirrors 13 and output devices 5, with output devices 5 shunted by AC additional resistor 18, the second current output input 9 differential cascade 3, inverting the signal at its second 7 input, connected to the input 12 current mirrors 13, and the first 8 current output input differential cascade 3 is related to the first 11 bus power supply.

The amplifier circuit prototype is shown on the drawing figure 1. On the drawing figure 2 presents the scheme of the claimed Yiwu in accordance with paragraph 1 of the claims.

On the drawing figure 3 shows Yiwu with increased damping of the output signal in the region of low frequencies with the concrete implementation of the input differential cascade 3 field-effect transistors 27, 28 (paragraph 2 of the claims).

On the drawing figure 4 shows Yiwu 2 with high attenuation in the region of low frequencies and implementation of the input differential cascade 3 according to the scheme on a ZSM-33) - Darlington transistors (p.3 claims).

On the drawing figure 5 presents the scheme of arrangement 2 is in the environment of the PSpice models of integrated transistors FSUE NLP "pulsar".

On the drawing Fig.6 shows the graph of the frequency dependence of gain schemes Yiwu figure 5 with the following parameters of elements of C 1 =2,1 p, C 2 =1,9 p, R 1 =1 K, R 2 =100 Ohms. Does the quality factor Q=10.

On the drawing 7 shows the scheme of arrangement 2 is in the environment of the PSpice models of integrated transistors FSUE HI 111 "pulsar" for the case when the signal source 1 is associated with the base of the input transistor VT17 input differential cascade 3 through separating capacitor C3.

On the drawing Fig is a graph of the frequency dependence of gain diagram 7 in C 1 =600 f, 2 =2, R 3 =2,1 R, R 2 =R 3 =700 Ohms, R 1 =1 KOhm. This of the quality factor Q=163.

On the drawing figure 9 presents the diagram of the device figure 4 in the environment of the PSpice models of integrated transistors FGUP NPP pulsar, which provides high weakening of the output signal in the range of low frequencies without using the input coupling capacitor and field-effect transistors.

On the drawing figure 10 shows the graph of the frequency dependence of gain schemes Fig.9 in C 1 =to 190.5 f, C 2 =10,5 f, R 1 =1 K, R 2 =460 Ohms. This of the quality factor Q=114.

Measuring amplifier with controlled parameters amplitude-frequency characteristics figure 2 contains the signal source 1, connected to the first input 2 input differential cascade 3, the first 4 correction capacitor AC between output 5 and common bus power supply 6, with the second input 7 input differential cascade 3 is associated with the exit device 5, the first 8 and 9 second current output input differential cascade 3, the first 10 ecostability dvuhgolosyj included between the first 11 bus power supply and input 12 current mirrors 13, 14 second ecostability dvuhgolosyj included between 15 current mirrors 13 and the first 11 bus power source, the second 16 correction capacitor, the second 17 bus power supply, consistent with the emitter circuit input differential cascade 3. The second 16 correction capacitor connected between the output of the 15 current mirrors 13 and output devices 5, with output devices 5 shunted by AC additional resistor 18, the second current output 9 input differential cascade 3, inverting the signal at its second 7 input, connected to the input 12 current mirrors 13, and the first 8 current output input differential cascade 3 is related to the first 11 bus power supply.

On the drawing figure 2 input differential cascade 3 implemented transistors 19 and 20, as well as the current source 21. Resistor 22 establishes a static mode transistor 20. Source voltage input 1 input contains EF 24 and separating capacitor 23. Current mirror 13 executed under the traditional scheme and contains the p-n junction 25 and the transistor 26, the base of which is the current input 12.

On the drawing figure 3, in accordance with claim 2, input differential cascade 3 implemented on the ground 27 and 28 second field-effect transistors, United origins of which are connected with the second 17 bus power supply through subsidiary ecostability dvuhgolosyj 29.

On the drawing figure 4, in accordance with paragraph 3 of the claims, the input differential cascade 3 implemented based on the composite Darlington transistors 30, 31, 32, 33 and 34 two-terminal, 35, 36, providing a static mode of the scheme.

Consider the work of the proposed scheme figure 3.

Input signal u of I (1) change the currents of differential pair implemented transistors 27 and 28. Change of a current drain transistor 28 causes a change in the input voltage, current mirrors 13 and collector current bipolar transistor 26. The nature of collecting loads the transistor, formed by the resistors 14, 18 and capacitors 16, 4, leads to the frequency dependence of voltage across the resistor 18, the appropriate response and the response of the election of the amplifier. Indeed, the effect of capacitive divider on the capacitors 16 and 4 weakens currents resistor 18 in the range of low and high frequencies in the vicinity of the frequency of quasiresonant f 0 . Output voltage Yiwu (site 5) differential interacts with an input voltage 1 and changes the drain current of the transistor 28 and, therefore, current collector 26. Thus, the connection output circuit 5 Yiwu to the gate of the transistor 28 implements a scheme in a feedback circuit, frequency dependence of which corresponds to the characteristic of the band pass filter. The depth of this feedback (OS) maximum only a single frequency, which corresponds to the frequency of quasiresonant (f 0 ) Yiwu. Into force of the regenerative properties of this OS is increased the bandwidth (Q) and a gain of PS (K 0 ) without changing the frequency of quasiresonant f 0 .

Comprehensive gain Yiwu figure 3 as the ratio of output voltage u vich (output 5) input voltage u of I (1) is determined by a formula that can be obtained using the methods of analysis of electronic circuits

where f is the frequency of the input signal;

f 0 is the frequency of quasiresonant Yiwu;

Q - q AFC Yiwu;

K 0 - gain Yiwu voltage at frequency of quasiresonant f 0 . And

where R 14 , R 18 (16 C , 4 C ) resistance capacitance) items 14 and 18 (16,4);

K i13 of about 1 - transfer ratio of the current-current mirror 13;

S 27 ≈S 28 ≈S 0 - slope of transistors on 27 and 28 input differential cascade 3.

From the formula (3) it follows that the change is equivalent steepness S can be independently implemented by the values of f 0 (formula 2) to set up Q schemes Yiwu by the specified value. For example, in the diagram of figure 3 this is easily accomplished by changing the current I 29 =2I 0 dvuhyarusnaya 29, as the steepness of transistors S 28 ≈S 27 ≈'s directly proportional to the static current source I I =I I =I 0 .

For the case when the input differential cascade 3 made bipolar transistors (for example, in the diagram figure 2), equivalent to the steepness S (5) is determined by the formula

where r E =r E =r e - emitter resistance transitions transistors 19 and 20.

Given the regime's dependence r e = & Phi; t /I e K i13 =1 the formula (6) can be simplified:

where f t =26 mV - temperature potential;

I 0 =0,5I 21 - half of the current dvuhyarusnaya 21.

Thus, changing the current I 0 , you can control the value of the quality factor Q, implemented in the schemes of the claimed device figure 3, figure 2.

In addition, an important additional property diagrams 2 and 3 is a relatively small impact stray capacitance transistor on the basic parameters 0 and f Q. Indeed, for the circuit figure 3 it can be shown that the relative change the main settings, Yiwu

where From I - input capacitance transistor 28;

In bipolar basis of the elements in the schema Yiwu 2 to decrease at low frequencies direct transmission input 1 on the chain "base of the transistor 20 - emitter voltage transistor 20 - emitter voltage transistor 19 - base of the transistor 19", depending on their amplification current base of these transistors (?=50 to 200), need more separation capacity 23 in the input chain, which is shown in the input source 1.

In the proposed scheme, Yiwu through the application of field-effect transistors 27 and 28 (3) this effect is considerably weakened, and the asymptotic decay at low frequencies are small due to lack of transfer changes currents source transistors on 27 and 28 in the circuit of the transistor 28, i.e. to the output device 5.

A similar property has Yiwu figure 4, in which the cascade 3 performed on a composite Darlington transistors (figure 4).

Thus, the claimed circuit decision Yiwu characterized by higher values of gain To 0 on the frequency of quasiresonant f 0 , elevated values of the quality factor Q, characterizing his election properties, as well as higher weakening of the output signal in the range of low frequencies. This combination of properties Yiwu allows to ensure its effective use for the purposes of measurement of parameters of high-frequency signals and their amplification.

THE BIBLIOGRAPHIC LIST

1. Design of Bipolar Differential OpAmps with Unity Gain Bandwidth of up to 23 GHz \ N.Prokopenko, A. Budyakov, K.Schmalz, C.Scheytt, P.Ostrovskyy \\ Proceeding of the 4-th European Conference on Circuits and Systems for Communications - ECCSC'08 / - Politehnica University, Bucharest, Romania: July 10-11, 2008. - pp.50-53.

2. Microwave SF-blocks of communication systems on the basis of fully differential operational amplifiers \ Prokopenko N., Budakov A.S., .Schmalz, .Scheytt \\ the problems of development of micro - and nanoelectronic systems - 2010. Collection of papers / edited edited by the academician of RAS Alemannische. - M: IPPM RAS, 2010. - S-586.

3. Patent US 4843343.

4. Patent US 4590435, fig.5.

5. Patent US 4999585, fig.2.

6. Patent US 6307438, fig.2.

7. Patent US 4267518, fig.4.

8. Patent WO 03052925.

9. The patent application US 2008/0246538, fig.3.

10. The patent application US 2010/0201437.

1. Measuring amplifier with controlled parameters amplitude-frequency response containing the source (1), connected to the first input (2) differential input stage (3), first (4) correction capacitor AC between the output device (5) and common bus power source (6), and a second entrance (7) input differential cascades (3) associated with output device (5), first (8) and second (9) current outputs input differential cascades (3), first (10) ecostability dvuhgolosyj included between the first (11) bus power supply and input (12) current mirror (13), second (14) ecostability dvuhgolosyj connected between the output (15) current mirror (13) and the first (11) bus power supply, the second (16) correction capacitor, the second (17) bus power supply, consistent with the emitter circuit input differential cascade (3), wherein the second (16) correction capacitor connected between output (15) current mirror (13) and output devices (5), and the output device (5) shunted by AC additional resistor (18), the second current output (9) input differential cascades (3)that inverts the phase of a signal at its second (7) input, connected to the input (12) current mirror (13), and the first (8) current output differential input stage (3) is related to the first (11) bus power supply.

2. Measuring amplifier with controlled parameters amplitude-frequency characteristics of claim 1, characterized in that the input differential cascade (3) implemented on the ground (27) and the second (28) field-effect transistors, United origins of which are connected with a second (17) bus power supply through subsidiary ecostability dvuhgolosyj (29).

3. Measuring amplifier with controlled parameters amplitude-frequency characteristics of claim 1, characterized in that the input differential cascade (3) is realized on the basis of the integral (30), (31) and (32), (33) transistor Darlington.