RU2474040C1 - Selective amplifier - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: selective amplifier includes input voltage source (1), input transistor (2), the emitter of which is connected through the first (3) current-stabilising bipole to the first (4) power supply bus; base is connected to potential bias circuit (5); collector is connected to emitter of output transistor (6) and through the second (7) current-stabilising bipole to the second (8) power supply bus; base of output transistor (6) is connected to additional voltage source (9), and collector is connected to output of device (10) and through the first resistor (11) to the first (4) power supply bus. The first (12) balancing capacitor is connected between emitter of input transistor (2) and collector of output transistor (6); collector of input transistor (2) is connected to emitter of output transistor (6) through the second (13) resistor and to input voltage source (1) through the second (14) balancing capacitor.

EFFECT: improving Q factor of amplitude-frequency response of the amplifier and its voltage amplification factor at quasi-resonance frequency f₀.

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Description

The present invention relates to the field of radio engineering and communications and can be used in microwave filtering devices of radio signals from cellular communication systems, satellite 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 problems of extracting high-frequency and microwave signals [1, 2]. However, the classical construction of such selective amplifiers (DIs) (RC filters) is accompanied by significant energy losses, which are mainly used to ensure the static mode of a sufficiently large number of auxiliary, universal transistors forming an operational amplifier of the microwave range [1, 2]. In this regard, quite urgent is the task of constructing microwave highly specialized selective amplifiers on transistors, which provide the selection of a spectrum of signals with a sufficiently high quality factor of the resonant characteristic Q = 2 ÷ 10 and f ₀ = 1 ÷ 5 GHz.

Known schemes of selective amplifiers (DUTs) based on the so-called “bent” cascades [3-10], which provide the formation of the amplitude-frequency characteristics of the voltage gain (AFC) in a given frequency range Δf = f _in -f _n . 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 the input correction capacitor.

The closest prototype of the claimed device is a selective amplifier, presented in patent US 4.406.990. It contains an input voltage source 1, input transistor 2, the emitter of which is connected through the first 3 current-stabilizing two-terminal to the first 4 bus of the power supply, the base is connected to the potential bias circuit 5, the collector is connected to the emitter of the output transistor 6 and through the second 7 current-stabilizing two-terminal is connected to the second 8 by a power supply bus, the base of the output transistor 6 is connected to an additional voltage source 9, and the collector is connected to the output of the device 10 and through the first resistor 11 is connected to the first 4 bus power source.

амплитудно-частотной характеристики (АЧХ) и коэффициент усиления по напряжению К₀>1 на частоте квазирезонанса (f₀=1÷5ГГц).A significant disadvantage of the known device 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 = 1 ÷ 5 GHz).

The main objective of the invention is to increase the quality factor of the frequency response of the amplifier and its voltage gain at the frequency of quasi-resonance f ₀ . This allows in some cases to reduce the overall energy consumption and implement a high-quality microwave device with f ₀ = 1 ÷ 5 GHz.

The problem is solved in that in the selective amplifier of Fig. 1, containing an input voltage source 1, an input transistor 2, the emitter of which through the first 3 current-stabilizing two-terminal network is connected to the first 4 bus of the power source, the base is connected to the potential bias circuit 5, the collector is connected to the emitter the output transistor 6 and through the second 7 the current-stabilizing two-terminal is connected to the second 8 bus of the power source, the base of the output transistor 6 is connected to an additional voltage source 9, and the collector is connected to the output of device 10 and through the first resistor 11 is connected to the first 4 bus of the power source, new elements and connections are provided - between the emitter of the input transistor 2 and the collector of the output transistor 6, the first 12 correction capacitor is connected, the collector of the input transistor 2 is connected to the emitter of the output transistor 6 through the second 13 resistor and is connected to the input voltage source 1 through the second 14 correction capacitor.

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

Figure 3 shows a diagram of the inventive DUT of figure 2 in a Cadence environment on SiGe models of integrated transistors.

Figure 4 shows the dependence of the voltage gain and phase shift on the frequency of the DUT of Figure 3 on a large scale, and Figure 5 shows the frequency dependence of the gain and phase shift of the DUT of Figure 3 on a smaller scale.

The selective amplifier of Fig. 2 contains an input voltage source 1, an input transistor 2, the emitter of which through the first 3 current-stabilizing two-terminal network is connected to the first 4 bus of the power source, the base is connected to the potential bias circuit 5, the collector is connected to the emitter of the output transistor 6 and through the second 7 current-stabilizing the bipolar is connected to the second 8 bus of the power source, the base of the output transistor 6 is connected to an additional voltage source 9, and the collector is connected to the output of the device 10 and through the first resistor p 11 is connected to the first 4 bus power source. The first 12 correction capacitor is connected between the emitter of the input transistor 2 and the collector of the output transistor 6, the collector of the input transistor 2 is connected to the emitter of the output transistor 6 through a second 13 resistor and connected to the input voltage source 1 through the second 14 correction capacitor.

Consider the operation of the DUT figure 2.

The source of the input signal u _in (1) through the input differentiating circuit formed by the capacitor 14 and the resistor 13 changes (in accordance with the indicated law) the input (emitter) current of the transistor 6. The collector load of this transistor (resistor 11 and capacitor 12) is provided by the integrating the law of conversion of this current into the output voltage of the DUT (Output.u). In this regard, the frequency response of the DUT has an extremum at the quasi-resonance frequency (f ₀ ) and zero asymptotic values of the transmission coefficient. The conversion of part of the output voltage of the DUT through the capacitor 12 to the additional emitter current of the transistor 2 contributes to the implementation of the regenerative feedback loop. In this case, the capacitor 12 and the input resistance of the transistor 2 form a differentiating circuit, and a parallel (alternating current) connection of the capacitor 14 and the resistor 13 forms an integrating circuit for converting the collector current of the transistor 2 into changes in the emitter current of the transistor 6. Thus, the nature of the frequency dependence of the input feedback loop coupling coincides with the frequency response and phase response of the DUT and, therefore, the action of this feedback is aimed at increasing the quality factor Q and gain K ₀ at a constant frequency of quasi-resonance.

Let us show analytically that higher values of K ₀ and Q in the operating frequency range are implemented in the scheme of figure 2.

Indeed, as a result of the analysis, we can find that the complex voltage transfer coefficient of the DUT of FIG. 2 is determined by the formula

where f is the signal frequency;

f ₀ is the frequency of quasi-resonance,

,

,

K ₀ - gain of the DUT at a frequency f ₀ ,

Q - quality factor, and:

α _i - current transfer coefficient of the i-th emitter of the transistor. Thus, the numerical values of the coefficients α ₂ and α ₆ provide the necessary (required) values of the quality factor Q and gain K _{0 of the} IUT with a constant (unchanged) value of its quasi-resonance frequency f ₀ (2).

The most important property of the proposed IU scheme is the possibility of parametric optimization of its elemental sensitivity with a relatively low quality factor. As can be seen from (4) when the condition

quality factor reaches its maximum value

In the diagram of FIG. 2, structural optimization of both the Q factor of Q and its sensitivity is provided. Indeed, in the case under consideration

Coefficients of parametric sensitivity when condition (5) is satisfied:

In this case, the frequency of quasi-resonance (2) and its parametric sensitivity remain unchanged.

As seen from the figure 3, which shows a practical implementation of the circuit 2, the conditions set forth above are easily implemented on the basis of complementary bipolar transistors, providing the input voltage u transform _Rin during the input current i _{input 1.}

These theoretical conclusions confirm the graphs of figure 4, figure 5. Thus, the claimed circuit solution is characterized by higher values of the gain K ₀ at the frequency of the quasi-resonance f ₀ and increased values of the quality factor Q at low parametric sensitivity and, therefore, high stability of its frequency characteristics.

BIBLIOGRAPHIC LIST

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 / - Politehnica 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, S.Scheytt // Problems of Developing Advanced Micro- and Nanoelectronic Systems - 2010. Proceedings / under the general. ed. Academician of the Russian Academy of Sciences A.L. Stempkovsky. - M .: IPPM RAS, 2010. - P.583-586.

3. Patent US 4,406,990, fig. 3, fig. 2.

4. Patent US 6.734.937, fig. 7.

5. Patent US 4,600,893, fig. 6.

6. Patent US 6.448.853, fig. 5.

7. Patent US 5.091.701 fig. 1.

8. Patent US 7.560.987 fig.15.6.

9. Patent US 3.644.838.

10. Patent US 4.649.352 fig. 1.

Claims (1)

A selective amplifier containing an input voltage source (1), an input transistor (2), the emitter of which is connected to the first (4) bus of the power supply via the first (3) current-stabilizing two-terminal device, the base is connected to the potential bias circuit (5), the collector is connected to the emitter output transistor (6) and through the second (7) current-stabilizing two-terminal device is connected to the second (8) bus of the power source, the base of the output transistor (6) is connected to an additional voltage source (9), and the collector is connected to the output of the device (10) through the first resistor (11) is connected to the first (4) bus of the power source, characterized in that between the emitter of the input transistor (2) and the collector of the output transistor (6) the first (12) correction capacitor is connected, the collector of the input transistor (2) is connected to the emitter output transistor (6) through the second (13) resistor and is connected to the input voltage source (1) through the second (14) correction capacitor.

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