RU2475938C1 - Selective amplifier - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: amplifier comprises an input transistor (1), the emitter of which via the first (2) current-stabilising dipole is connected with the first (3) bus of the power supply source, the base is connected to the first (4) source of auxiliary voltage, and the collector is connected with the input of a current mirror (5), having a common emitter output (6), matched with the second (7) bus of the power supply source, the first (8) frequency-setting resistor, connected by AC in parallel to the first (9) correcting capacitor. The common emitter output (6) of the current mirror (5) is connected to the second (7) bus of the power supply source via the first (8) frequency-setting resistor and is connected to the emitter of the input transistor (1) via serially connected the second (10) frequency-setting resistor and the second (11) correcting capacitor, the common unit of the second (10) frequency-setting resistor and the second (11) correcting capacitor is connected with the input (12) of the additional current amplifier (13) via the third (14) correcting capacitor, besides, the current input (15) of the device is connected with the emitter (or the collector) of the input transistor (1), and the inverting current output of the current mirror (5) is connected to the second (16) source of auxiliary voltage.

EFFECT: higher quality of amplifier amplitude-frequency characteristic and its amplification ratio by voltage 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 tasks of extracting high-frequency and microwave 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 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 three to four transistors, which provide the selection of a spectrum of signals with a sufficiently high quality factor of the resonance characteristic Q = 2 ÷ 10 and f ₀ = 1 ÷ 5 GHz.

Known schemes for selective amplifiers based on cascades with a controlled current mirror [3-11], 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 US patent No. 4.999.585, fig.2. It contains an input transistor 1, the emitter of which is connected through the first 2 current-stabilizing bipolar to the first 3 bus of the power supply, the base is connected to the first 4 auxiliary voltage source, and the collector is connected to the input of the current mirror 5, which has a common emitter output 6, matched with the second 7 bus power supply, the first 8 frequency-setting resistor connected by alternating current parallel to the first 9 correction capacitor.

амплитудно-частотной характеристики (АЧХ) и коэффициент усиления по напряжению К₀>1 на частоте квазирезонанса (f₀=1÷5 ГГц).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 total power 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 transistor 1, the emitter of which is connected through the first 2 current-stabilizing two-terminal to the first 3 bus of the power source, the base is connected to the first 4 source of auxiliary voltage, and the collector is connected to the input of the current mirror 5 having a common emitter output 6, coordinated with the second 7 bus power source, the first 8 frequency-setting resistor connected by alternating current parallel to the first 9 correction capacitor is provided new elements and connections - the common emitter output 6 of the current mirror 5 is connected to the second 7 bus of the power source through the first 8 frequency-setting resistor and connected to the emitter of the input transistor 1 through a second 10 frequency-setting resistor and second 11 correction capacitor, a common node of the second 10 frequency-setting resistor and the second 11 correction capacitor is connected to the input 12 of an additional current amplifier 13 through the third 14 correction capacitor, and the current input 15 of the device is connected to the emitter (or collector) of the input transistor 1, and the inverting current output of the current mirror 5 is connected to the second 16 source of auxiliary voltage.

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 DUT of figure 2 with a specific implementation of the main functional units, which shows a typical embodiment of a current mirror 5 containing a pn junction 21 and a transistor 20, as well as an additional current amplifier 13.

Figure 4, figure 5 shows the construction options for the input voltage-current converters, providing (if necessary) the conversion of the potential input signal into a current signal supplied to the input of the device 15.

Figure 6 presents a diagram of the inventive amplifier of figure 3 in the Cadence environment on models of SiGe transistors.

Fig.7 shows the dependence of the voltage gain and phase shift on the frequency of the DUT of Fig.6 on a large scale, and Fig.8 is a logarithmic amplitude-frequency characteristic of the DUT on a smaller scale.

The selective amplifier of Fig. 2 contains an input transistor 1, the emitter of which is connected through the first 2 current-stabilizing two-terminal to the first 3 bus of the power source, the base is connected to the first 4 auxiliary voltage source, and the collector is connected to the input of the current mirror 5 having a common emitter output 6, coordinated with a second 7 bus power supply, the first 8 frequency-setting resistor connected by alternating current parallel to the first 9 correction capacitor. The common emitter output 6 of the current mirror 5 is connected to the second 7 bus of the power source through the first 8 frequency-setting resistor and connected to the emitter of the input transistor 1 through a second 10 frequency-setting resistor and second 11 correction capacitor, a common node of the second 10 frequency-setting resistor and second 11 correction capacitor connected to the input 12 of an additional current amplifier 13 through the third 14 correction capacitor, and the current input 15 of the device is connected to the emitter (or collector) input of transistor 1, and the inverting current output of the current mirror 5 is connected to the second auxiliary voltage source 16.

Consider the operation of the DUT figure 2.

The input AC input source i _{input 1} with frequency f changes either the input current of the current mirror 5 or the emitter current of the input transistor 1. The resulting current increment is increased (amplified) by the current mirror 5, the load of which at output 6 is a frequency-setting circuit formed by resistors 8, 10 and capacitors 9, 11, 14. The specified frequency-setting circuit provides the necessary form of the frequency response and phase response of the DUT and implements through the interaction of the transistor 1 and the input of the current mirror 5 regenerative feedback, which turns out to be substances only at one frequency — the quasi-resonance frequency f _{0 of the} DUT. In the region of low frequencies (f << f ₀ ) and in the region of high frequencies (f >> f ₀ ) the same regenerative feedback is reactive. Therefore, the frequency of the quasi-resonance f ₀ does not depend on the depth of this feedback and is determined only by the values of the resistances R ₈ , R ₁₀ and capacitances C ₉ , C ₁₁ , C ₁₄ , and the numerical value of the quality factor Q and the gain K _{0 of the} DUT is determined by the return ratio of the real inverse communication and, therefore, the transfer coefficient of the current mirror 5.

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 frequency of the input signal;

K ₀ is the gain of the DUT at a frequency f ₀ ;

Q - quality factor;

where K _i13.6 and K _i are the current transfer coefficients of the current mirror 5 and the additional current amplifier 13;

α ₁ - current transfer coefficient of the emitter of transistor 1.

Thus, the numerical values of the coefficient K _{i13.6 of the} current mirror 5 provide the necessary (required) values of the Q factor Q and gain K _{0 of the} DUT with a constant (unchanged) value of its quasi-resonance frequency f ₀ (2).

The most important property of the proposed circuit is the ability to implement a frequency-setting circuit with a relatively high quality factor. As can be seen from (4), when R ₈ = R ₁₀ = R, C ₁₁ = C ₁₄ = C ₉ = C and the condition:

in the diagram of figure 2 provides the possibility of structural optimization of the current transfer coefficient of the current mirror 5 for the required value of quality factor.

As can be seen from figure 3, which shows the practical implementation of the circuit of figure 2, the above conditions are easily implemented on the basis of the current mirror by scaling the emitter junction of the transistor 20. In this case, the output converter in the circuit of figure 3 is made on the basis of the transistor 18 with a load of 20 .

These theoretical conclusions confirm the graphs of Fig.7, Fig.8.

Thus, the claimed circuit solution is characterized by higher values of the gain K ₀ at the frequency of quasi-resonance f ₀ and increased values of the quality factor Q, characterizing its selective properties.

Literature

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 N.N., Budyakov A.S., K. Schmalz, C. Schytt // Problems of developing promising micro- and nanoelectronic systems - 2010. Proceedings. / under total. ed. Academician of the Russian Academy of Sciences A.L. Stempkovsky. - M .: IPPM RAS, 2010. - P.583-586.

3. Patent US 4.999.585, fig. 2.

4. Patent US 4.262.261, fig.1B.

5. Patent WO / 2002/047257.

6. Patent US 7.782.139, fig. 5.

7. Patent US 6.844.781.

8. Patent US 6.657.465.

9. Patent US 4.366.442, fig. 2.

10. Patent US 5.371.476, fig. 3.

11. Patent US 2006/0139098, fig. 1.

Claims (1)

A selective amplifier containing an input transistor (1), the emitter of which is connected through the first (2) current-stabilizing two-terminal to the first (3) bus of the power supply, the base is connected to the first (4) auxiliary voltage source, and the collector is connected to the input of the current mirror (5) having a common emitter output (6), consistent with the second (7) bus of the power source, the first (8) frequency-setting resistor connected by alternating current parallel to the first (9) correction capacitor, characterized in that the common emitter output (6) t the shunt mirror (5) is connected to the second (7) bus of the power source through the first (8) frequency-setting resistor and is connected to the emitter of the input transistor (1) through the second-time (10) frequency-setting resistor and the second (11) correction capacitor, a common node of the second (10) a frequency-setting resistor and a second (11) correction capacitor is connected to the input (12) of an additional current amplifier (13) through a third (14) correction capacitor, and the current input (15) of the device is connected to the emitter (or collector) of the input transistor and (1) and the inverting current output of the current mirror (5) connected to the second (16) auxiliary voltage source.

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