RU2479109C1 - Selective amplifier - Google Patents

Abstract

FIELD: radio engineering, communications.

SUBSTANCE: selective amplifier comprises a current input (1), connected with a collector of an input transistor (2), the first (3) source of auxiliary voltage, connected to the base of the input transistor (2), the first (4) and second (5) frequency-setting resistors, the first (6) correcting capacitor, the first current-stabilising dipole (7). The collector of the input transistor (2) is connected with the first (8) bus of a supply source via the first frequency-setting resistor (4) and is connected with the common bus of supply sources (10) via serially connected second (AND) and the third (12) correcting capacitors, between the emitter of the input transistor (2) and the base of the additional transistor (14) there is a forward-biased p-n transition (15) connected, between the potential output of the device (13) and the base of the additional transistor (14) there is the second (5) frequency-setting resistor, the first correcting capacitor (6) is connected between the emitter of the input transistor (2) and the emitter of the additional transistor (14), the first (7) current-stabilising dipole is connected between the base of the additional transistor (14) and the second (9) bus of the supply source, the emitter of the additional transistor (14) is connected to the second (9) bus of the supply source via the second (15) current-stabilising dipole.

EFFECT: higher quality of selective amplifier amplitude-frequency characteristic and its amplification ratio by voltage at quasiresonance frequency f₀.

3 cl, 7 dwg

Description

The invention relates to the field of radio engineering and communications and can be used in devices for filtering radio signals, television, radar, etc.

Integrated operational amplifiers with special RC-correction elements that form the amplitude-frequency characteristic of the resonance type are widely used today in the tasks of extracting high-frequency signals [1, 2]. However, the classical construction of such selective amplifiers (DUTs) is accompanied by significant energy losses, which are mainly used to ensure the static mode of a sufficiently large number of secondary transistors forming an operational amplifier [1, 2]. In this regard, it is very urgent to build selective amplifiers on bipolar transistors, which provide a narrow spectrum of signals with a sufficiently high quality factor (Q) of the resonant characteristic (Q = 2 ÷ 10) with low power consumption.

Known schemes are DUTs integrated into the architecture of RC filters based on bipolar transistors, which provide the formation of the amplitude-frequency characteristics of the voltage gain in a given frequency range Δf = f _in -f _n [3-11]. Moreover, their upper cutoff frequency f _{in is} sometimes formed by the inertia of the transistors of the circuit (capacitance per substrate), and the lower f _n is determined by a correction capacitor.

The closest prototype of the claimed device is a selective amplifier, presented in patent RU 2421879, figure 2. It contains a current input 1 connected to the collector of the input transistor 2, the first 3 auxiliary voltage source connected to the base of the input transistor 2, the first 4 and second 5 frequency-setting resistors, the first 6 correction capacitor, the first current-stabilizing two-terminal 7, the first 8 and second 9 buses power sources.

амплитудно-частотной характеристики (АЧХ) и коэффициент усиления по напряжению K₀>1 на частоте квазирезонанса (f₀).A significant drawback of the known YiU prototype is that it does not provide high quality factor

amplitude-frequency characteristics (AFC) and voltage gain K ₀ > 1 at the frequency of quasi-resonance (f ₀ ).

The main objective of the invention is to increase the quality factor of the frequency response of the DUT and its voltage gain (K ₀ ) at the frequency of quasi-resonance f ₀ . This allows in some cases to reduce the overall energy consumption and implement a high-quality selective device.

The problem is solved in that in the selective amplifier of figure 1, containing a current input 1 connected to the collector of the input transistor 2, the first 3 auxiliary voltage source connected to the base of the input transistor 2, the first 4 and second 5 frequency-setting resistors, the first 6 corrective a capacitor, the first current-stabilizing two-terminal 7, the first 8 and second 9 buses of the power sources, new elements and communications are provided - the collector of the input transistor 2 is connected to the first 8 bus of the power source through the first frequency gate resistor 4 and is connected to the common bus of power supplies 10 through series-connected second 11 and third 12 correction capacitors, the common node of which is connected to the potential output of the device 13, between the emitter of the input transistor 2 and the base of the additional transistor 14, a forward biased pn junction 15 is connected, between the output of the device 13 and the base of the additional transistor 14 includes a second 5 frequency-setting resistor, the first correction capacitor 6 is connected between the emitter of the input transistor 2 and the emitter m of additional transistor 14, the first 7 current-stabilizing two-terminal is connected between the base of the additional transistor 14 and second 9 power supply bus, the emitter of the additional transistor 14 is connected to the second 9 bus of the power supply through the second 15 current-stabilizing two-terminal, and the collector of the additional transistor 14 is connected to the second 16 auxiliary source voltage.

The amplifier circuit of the prototype is shown in the drawing of figure 1. The drawing of figure 2 presents a diagram of the inventive device in accordance with claim 1 of the claims.

The drawing of figure 3 presents a diagram of the inventive device in accordance with claim 2 and claim 3 of the claims.

The drawing of figure 4 shows a diagram of the claimed IU in the computer simulation environment Cadence (process SG25H1).

The drawing of figure 5 shows the LACH and phase response of the DUT of figure 4 in a wide frequency range (from 1 kHz to 100 GHz) at R21 = 80 Ohms, C1 = 500 fF, C2 = 50 pF.

The drawing of Fig.6 shows the LACH and phase response of the DUT of Fig.4 in a narrower frequency range (from 100 MHz to 10 GHz) at R21 = 80 Ohms, C1 = 500 fF, C2 = 50 pF.

The drawing of Fig.7 shows the dependence of the Q factor on the resistance of the resistor R21 of the circuit of Fig.4.

The selective amplifier, figure 2, contains a current input 1 connected to the collector of the input transistor 2, the first 3 auxiliary voltage source connected to the base of the input transistor 2, the first 4 and second 5 frequency-setting resistors, the first 6 correction capacitor, the first current-stabilizing two-terminal 7, the first 8 and second 9 bus power supplies. The collector of the input transistor 2 is connected to the first 8 bus of the power source through the first frequency-setting resistor 4 and is connected to the common bus of the power sources 10 through series-connected second 11 and third 12 correction capacitors, the common node of which is connected to the potential output of the device 13, between the emitter of the input transistor 2 and the base of the additional transistor 14 includes a forward biased pn junction 15, between the potential output of the device 13 and the base of the additional transistor 14 a second 5 frequency-setting rubber a torus, the first correction capacitor 6 is connected between the emitter of the input transistor 2 and the emitter of the additional transistor 14, the first 7 current-stabilizing two-terminal is connected between the base of the additional transistor 14 and the second 9 power supply bus, the emitter of the additional transistor 14 is connected to the second 9 power supply bus through the second 15 bipolar, and the collector of the additional transistor 14 is connected to the second 16 source of auxiliary voltage.

In the drawing of FIG. 3, in accordance with claim 2, the potential of the common bus of power supplies 10 is used as the first 3 auxiliary voltage sources.

In addition, in the drawing of figure 3, in accordance with claim 3 of the claims, the potential of the common bus of power supplies 10 is used as the second 16 auxiliary voltage source.

To convert the voltage of the source of the input signal to the input signal of the current input 1 in the circuit of figure 3, the Converter "voltage-current" 18 with a slope of the conversion S1. As this functional unit, classic cascades with a common emitter, a common base or differential amplifiers can be used. A buffer amplifier 19 having an auxiliary output 20 ensures matching of the filter with its low resistance load.

In some cases, a collector load resistor may be included in the collector of transistor 16, which allows an additional current output of the device.

Consider the operation of the circuit of figure 3.

Source input current signal i _Rin modifies the collector current of the transistor circuit 2. Character collector load of the transistor formed by the resistors 4 and 5, and capacitors 11 and 12, converts this current into an output current of the resistor 5 amp circuit. Moreover, the presence of a capacitive divider formed by capacitors 11 and 12, provides a functional dependence of this current, corresponding to the frequency characteristics of the selective amplifier.

The complex transfer coefficient of the DUT of Fig. 3 as the ratio of the output voltage (outputs of the device 13, 20) to the input voltage u _in with a sufficiently large capacity of the first 6 correction capacitor is determined by the formula, which can be obtained using methods of analysis of electronic circuits:

where f is the frequency of the input signal;

f ₀ is the frequency of the quasi-resonance of the DUT;

Q is the quality factor of the frequency response of the selective amplifier;

To ₀ is the gain of the DUT at the frequency of quasi-resonance f ₀ .

Moreover

where C ₁₁ , C ₁₂ , R ₄ , R ₅ - the parameters of the elements 11, 12, 4 and 5;

r = h _11.2 (1 + m) + h _11.15 - equivalent resistance in the base circuit of the transistor 14; m is the number of parallel connected emitter junctions of the transistor 14;

h _11.i is the h-parameter of the i-th transistor in the circuit with a common base.

The quality factor of the DUT is determined by the formula

where α _i is the current transfer coefficient of the emitter of the i-th transistor;

- эквивалентное затухание пассивной цепи.

- equivalent attenuation of the passive circuit.

By choosing the parameters of the elements included in the formula (3), it is possible to provide Q >> 1.

The formula for the gain K ₀ in the complex transfer coefficient (1) has the form

where S ₁ - the steepness of the input Converter "voltage-current" 18.

An important feature of the circuit is the ability to optimize its parametric sensitivity.

The optimal ratio is the equality of the capacitances of the capacitors 11 and 12 (C ₁₁ = C ₁₂ ). In this regard, the necessary value of the quality factor Q can be realized both structurally (by choosing the number of emitter junctions (m) of transistor 14), and parametrically by establishing the relationship between the resistances of the resistors R ₄ and R ₅ ((R ₅ + r) / R ₄ = k ) In this case, the parametric sensitivity

determined by the ratio of the resistors (coefficient k). In this case, the numerical value of the number m of emitters of transistor 14:

allows you to get the specified value of the quality factor under the condition of equal chain rating (k = 1). Indeed, for m = 2, k = 1

where β ₂ = α ₂ (1-α ₂ ) ^-1 .

If you choose m = 3,

Note that the condition k = 1 is associated with minimizing the influence of the frequency properties of the applied bipolar transistors on the frequency of the quasi-resonance of the dc f ₀ and its Q factor Q. With regard to sensitivity (5), it affects the instability of the parameters of the dc only through the error due to the non-identity of the resistive elements ( ΔΘ _R ), which for modern technologies is much smaller than the relative deviations of these elements, which determine the stability of the frequency of quasi-resonance f ₀ .

The numerical values of the capacitor 6 (C ₆ ) should be chosen from the following considerations.

If C ₆ = 0, then in formulas (2) - (8) it should be assumed that m = 0. In practice, this means that the circuit of the DUT, Fig. 3, at C ₆ = 0 has practically no improvement in the parameters K ₀ and Q.

If C ₆ >> C ₁₁ , C ₆ >> C ₁₂ , then all formulas (2) - (8) are valid and the IE has increased values of Q and K ₀ .

In practical schemes, the capacity of C ₆ can be commensurate with C ₁₁ and C ₁₂ (figure 4).

The relations obtained above for Q and K _{0 are} valid when the inequality

which in the field of high operating frequencies of the DUT is not rigid.

The above structural features of the IUT circuit allow, if necessary, to realize the extremely low sensitivity of its Q factor. As it follows from (3), (5) and (6), the condition

which requires an appropriate selection of the areas of transistors 14 and 15, allows to minimize the parametric sensitivities of the quality factor of the DUT

In this case, the numerical value of Q is determined by the ratio of the resistors of the circuit

and, as can be seen from (2), this provides an unambiguous choice of capacitors 11 (C ₁₁ ) and 12 (C ₁₂ ).

In addition, all modifications of the claimed DUT are implemented on n-p-n transistors, which is their significant advantage, for example, in the construction of radiation-resistant products.

Presented on the drawings of FIGS. 5 to 7, the simulation results of the proposed DUT of FIG. 4 confirm the indicated properties of the claimed circuit.

Thus, the proposed circuitry solution of the DUT is characterized by higher values of the gain coefficient K ₀ at the frequency of quasi-resonance f ₀ , as well as increased values of the quality factor Q, characterizing its selective properties.

Information sources

1. Design of Bipolar Differential OpAmps with Unity Gain Bandwidth 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 / Politchnica University, Bucharest, Romania: July 10-11, 2008, - pp. 50-53.

2. Microwave SF blocks of communication systems based on fully differential operational amplifiers / Prokopenko NN, Budyakov AS, K.Schmalz, C.Scheytt // Problems of Development of Promising Micro- and Nanoelectronic Systems - 2010. Proceedings / Under the total. ed. Academician of the Russian Academy of Sciences A.L. Stempkovsky. - M .: IPPM RAS, 2010. - P.583-586.

3. Patent US 4.267.518.

4. Patent WO 2003/052925, fig. 3.

5. Patent application US 2011/0169568, fig. 4.

6. Patent US 7.135.923.

7. Patent US 3.843.343.

8. Patent application US 2008/0122530.

9. Patent US 6.972.624, fig.6A.

10. Patent application US 2011/0109388.

11. Patent US 5.298.802.

Claims (3)

1. A selective amplifier containing a current input (1) connected to the collector of the input transistor (2), the first (3) auxiliary voltage source connected to the base of the input transistor (2), the first (4) and second (5) frequency-setting resistors, the first (6) correction capacitor, the first current-stabilizing two-terminal (7), the first (8) and second (9) power supply buses, characterized in that the collector of the input transistor (2) is connected to the first (8) power supply bus through the first frequency-setting resistor (4) and connected to a common source bus power supply (10) through series-connected second (11) and third (12) correction capacitors, the common node of which is connected to the potential output of the device (13), a forward biased pn junction is connected between the emitter of the input transistor (2) and the base of the additional transistor (14) (15), between the potential output of the device (13) and the base of the additional transistor (14), a second (5) frequency-setting resistor is connected, the first correction capacitor (6) is connected between the emitter of the input transistor (2) and the emitter of the additional transistor (14), The first (7) current-stabilizing two-terminal is connected between the base of the auxiliary transistor (14) and the second (9) power supply bus, the emitter of the additional transistor (14) is connected to the second (9) power-supply bus through the second (15) current-stabilizing two-terminal, and the collector of the additional transistor (14) is connected to a second (16) auxiliary voltage source. 2. The selective amplifier according to claim 1, characterized in that the potential of the common bus of the power sources (10) is used as the first (3) auxiliary voltage source. 3. The selective amplifier according to claim 1, characterized in that the potential of the common bus of the power sources (10) is used as the second (16) auxiliary voltage source.

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