RU2475939C1 - Selective amplifier - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: amplifier comprises a current input of a device (1), the first (2) input transistor, the emitter of which via the first (3) current-stabilising dipole is connected with the first (4) bus of the power supply source, and the base is connected to the additional source of voltage (5), a current mirror (6), the first (7) and second (8) correcting capacitors, at the same time the collector of the first (2) input transistor is connected with the input of the current mirror (6), between the common emitter output of which and the common bus of power supply sources there is the first (7) correcting capacitor connected by AC, besides, between the common emitter output of the current mirror (6) and the second (9) bus of the power supply source there are serially connected the first (10) and the second (11) frequency-setting resistors, the common unit of which is connected with the emitter of the first (2) input transistor via the second (8) correcting capacitor and via the third (12) correcting capacitor it is connected with the input of the additional current amplifier (13), and the current input of the device (1) is connected with the emitter of the first (2) input transistor or the input of the current mirror (6).

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 (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 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 of selective amplifiers (DUTs) based on the so-called “bent” cascodes [3-14], 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 a correction capacitor.

The closest prototype of the claimed device is a selective amplifier, presented in patent US 7.679.445. It contains the current input of device 1, the first 2 input transistor, the emitter of which is connected through the first 3 current-stabilizing two-terminal devices to the first 4 bus of the power source, and the base is connected to an additional voltage source 5, current mirror 6, first 7 and second 8 correction capacitors.

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 figure 1, containing the current input of the device 1, the first 2 input transistor, the emitter of which is connected through the first 3 current-stabilizing bipolar to the first 4 bus power supply, and the base is connected to an additional voltage source 5, a current mirror 6, first 7 and second 8 correction capacitors, new elements and connections are provided - the collector of the first 2 input transistor is connected to the input of the current mirror 6, between the common emitter output of which and the common bus and of the power supply points, the first 7 correcting capacitor is turned on by alternating current, and between the common emitter output of the current mirror 6 and the second 9 bus of the power supply, the first 10 and second 11 frequency-determining resistors are connected in series, the common node of which is connected to the emitter of the first 2 input transistor through the second 8 corrective the capacitor and through the third 12 correction capacitor is connected to the input of the additional current amplifier 13, and the current input of the device 1 is connected to the emitter of the first 2 input transistor ra or current mirror input 6.

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

Figure 3 shows the circuit of the RTU of figure 2 in accordance with claim 3 of the claims and the specific implementation of the main functional units, which shows the design of the current mirror 6 containing the pn junction 16 and the transistor 17.

Figure 4 shows a diagram of the inventive DUT of figure 3 in a Cadence environment on SiGe transistor models.

Figure 5 shows the dependence of the voltage gain on the frequency of the DUT of Figure 4 on a large scale, and Figure 6 shows the frequency dependence of the gain and the phase shift of the DUT of Figure 4 on a smaller scale.

The selective amplifier of Fig. 2 contains the current input of device 1, the first 2 input transistor, the emitter of which is connected through the first 3 current-stabilizing two-terminal devices to the first 4 bus of the power supply, and the base is connected to an additional voltage source 5, current mirror 6, first 7 and second 8 corrective capacitors. The collector of the first 2 input transistor is connected to the input of the current mirror 6, between the common emitter output of which and the common bus of power supplies, the first 7 correction capacitor is connected, alternatingly connected between the common emitter output of the current mirror 6 and second 9 of the power supply bus first 10 and the second 11 frequency-setting resistors, the common node of which is connected to the emitter of the first 2 input transistor through the second 8 correction capacitor and through the third 12 correction capacitor connected to the input of the additional current amplifier 13 and the current input device 1 is connected to the emitter of the first input transistor 2 and input of the current mirror 6.

In Fig.2, in accordance with claim 2, the output of the additional current amplifier 13 is connected to the potential output of the device 14 and is connected through the auxiliary resistor 15 to the first 4 bus of the power source.

In Fig. 3, in accordance with claim 3, between the input voltage source of the device and the current input 1 of the device, a voltage-current converter 16 is turned on, the current mirror 6 is implemented on the transistor 17 and pn junction 18, and an additional current amplifier 13 contains a transistor 19 and a current source 20.

Consider the operation of the DUT figure 2.

Input ac signal source as a current _{input 1} or i (i _INP2) changes the emitter current of the first input transistor 2, or directly to the input current of the current mirror 6. These changes through at K _i13.6 current transmission rate is transmitted in a frequency-dependent load mirror circuit of the current mirror 6. The structure of this load circuit, formed by resistors 10, 11 and capacitors 7, 8, 12, provides a band-pass type of frequency characteristics of the DUT - capacitor 7 - forms a decrease in the amplitude of the currents of capacitors 8 and 12 in the high-frequency region of the DUT and capacitors 8 and 12 reduce the signal in the low-frequency region of the DUT. As a result, the currents flowing through the capacitors 8 and 12 provide a band-pass selection of the output current of the current mirror 6. That is why the current flowing through the capacitor 12 leads to a change in the input current of the additional current amplifier 13, the output of which by means of the resistance of the auxiliary resistor 15 provides a change in the output voltage (14 ) in accordance with the frequency dependence of its gain required for the DUT. Similarly, the current of the capacitor 8 changes the emitter current of the transistor 2 and, therefore, the output current of the current mirror 6. The coincidence of the form of the frequency dependence of this current with the characteristics of the DUT allows realizing reactive feedback in the high-frequency region and in the low-frequency region of the DUT, increasing the attenuation signals in this frequency range at the output 14. Thus, only at one frequency (the quasi-resonance frequency of the ИУ f ₀ ) phase shifts in the feedback loop of the ИУ coincide, and the numerical value of the current transfer coefficient K _i13.6 will be aimed at improving the quality factor Q and the gain K _{0 of the} selective amplifier.

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

K ₀ - gain u _y at a frequency f ₀

Q - quality factor, and:

K _i13.6 and K _id - current transfer coefficients of the current mirror 6 and the additional current amplifier 13;

α ₂ - current transfer coefficient of the emitter of transistor 2.

Thus, the numerical values of the coefficient K _{i13.6 of the} current mirror 6 provide the necessary (required) values of the Q factor 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 scheme is the possibility of parametric optimization of its elemental sensitivity at a relatively high Q factor. As can be seen from (4) with R ₁₁ = R ₁₀ = R and the condition

in the diagram of figure 2 provides the possibility of structural optimization of both the Q factor of Q, and its sensitivity. Indeed, in the case under consideration, the Q factor:

and its sensitivity factors:

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 can be easily implemented based on the input converter "voltage-current" 16 (differential stage), which provides the input voltage u transform _Rin during the input current u _y i ₁ , as well as a current mirror 6 based on a multi-emitter transistor 17 and pn junction 18, which at C ₁₂ = C ₈ provides the implementation of condition (3) and an additional current amplifier 13 made on the basis of bipolar transistor 19.

These theoretical conclusions confirm the graphs of Fig.5, Fig.6.

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, S.Scheytt. // Problems of development of 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 7.679.445.

4. Patent US 6.734.737, fig. 7.

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

6. Patent US 6.448.853, fig. 5.

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

8. Patent US 3.440.448.

9. Patent application US 2002/0196079, fig. 1.

10. Patent US 5.091.701, fig. 1.

11. Patent US 6.448.853, fig. 5.

12. Patent US 7.560.987, fig.15.6.

13. Patent US 3.644.838.

14. Patent US 4.649.352, fig. 1.

Claims (3)

1. A selective amplifier containing the current input of the device (1), the first (2) input transistor, the emitter of which through the first (3) current-stabilizing two-terminal device is connected to the first (4) bus of the power source, and the base is connected to an additional voltage source (5), current mirror (6), first (7) and second (8) correction capacitors, characterized in that the collector of the first (2) input transistor is connected to the input of the current mirror (6), between the common emitter output of which and the common bus of power supplies alternating current ne a correcting capacitor (7), and between the common emitter output of the current mirror (6) and the second (9) power supply bus, the first (10) and second (11) frequency-determining resistors are connected in series, the common node of which is connected to the emitter of the first (2) the input transistor through the second (8) correction capacitor and through the third (12) correction capacitor is connected to the input of an additional current amplifier (13), and the current input of the device (1) is connected to the emitter of the first (2) input transistor or the input of the current mirror (6) . 2. The selective amplifier according to claim 1, characterized in that the output of the additional current amplifier (13) is connected to the potential output of the device (14) and is connected through the auxiliary resistor (15) to the first (4) bus of the power source. 3. The selective amplifier according to claim 1, characterized in that between the source of the input voltage of the device and the current input (1) of the device is included in the Converter "voltage-current" (16).

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