RU2534972C1 - Broadband non-inverting amplifier with low non-linear noise and harmonic distortion - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: broadband non-inverting amplifier comprises a non-inverting output stage (1), the input of which is connected to the input of the device (2) and an input voltage source (3) through a matching resistor (4), a load circuit (5) connected to the output (6) of the device, connected to the output of the non-inverting output stage (1). Between the input (2) and output (6) of the device there are inverting buffer amplifier (7), the second (8) and the third (9) auxiliary resistors installed, connected in series. The common assembly of the resistors is connected to the input of correcting stage (11), whose current output (12) is connected to the input of non-inverting output stage (1).

EFFECT: lower level of nonlinear distortions and different types of noise in the load circuit of the broadband non-inverting amplifier with a non-inverting output stage.

3 cl, 19 dwg

Description

The invention relates to the field of radio engineering and communication and can be used as a device for precision power amplification of analog signals, in the structures of non-inverting amplifiers and output stages for various functional purposes, including RF and microwave ranges.

In modern electronic equipment, broadband non-inverting amplifiers (SHNU) are used that provide power amplification and conversion of input signals [1-15].

The closest in essence to the claimed technical solution is the classical scheme of the SNU of FIG. 1, presented in the patent US 5.512.859, the architecture of which is also present in a large number of other patents and monographs, for example [1 ÷ 17]. In many practical cases, the non-inverting output stage of the SNU is implemented according to the scheme with sequential negative voltage feedback (Fig. 3), and such a solution of the SNU is classic for its many applications [16-17].

A significant disadvantage of the known SHNU figure 1 (figure 2, figure 3) is that it is characterized by an increased level of non-linear distortion, which is measured by the harmonic coefficient. This disadvantage is a consequence of the nonlinear operating modes of the transistors of the output stage of the SNU, as well as the influence on the nonlinear distortions of the sinusoidal signal of the final values of the maximum slew rate of the output voltage of the SNU [16, 17].

The main objective of the invention is to reduce the level of nonlinear distortion and noise of various origins in the load circuit of an SNU with non-inverting output stage.

The problem is solved in that in the broadband non-inverting amplifier of figure 1 (figure 2, figure 3), containing a non-inverting output stage 1, the input of which is connected to the input of the device 2 and the input voltage source 3 through a terminating resistor 4, load circuit 5, connected to the output 6 of the device associated with the output of the non-inverting output stage 1, new elements and connections are provided - between the input 2 and the output 6 of the device, an inverting buffer amplifier 7, a second 8 and a third 9 accessory are connected in series s resistors, the common node 10 of the second 8 and third 9 additional resistors connected to the input of the correction stage 11, the current output 12 which is connected to the noninverting input of the output stage 1.

The amplifier circuit of the prototype is shown in figure 1. Figure 2 presents the functional diagram of the amplifier of the prototype of figure 1.

Figure 3 shows the circuit corresponding to figure 2, which gives a specific example of building a non-inverting output stage 1 with a stable transmission coefficient based on the operational amplifier A1 and resistors R1 and R2.

Figure 4 presents a diagram of the inventive device in accordance with claim 1, claim 2 and claim 3 of the claims. Here, the voltage source _Ush models the generation of non-linear distortions in the circuit of Fig. 4, due to the non-inverting output stage 1, as well as noise and interference of various nature. As a rule, these are the second, third, and other harmonics of the main signal u _in .

Figure 5 shows a diagram of figure 4 in the environment of PSpice, on the basis of which a computer study of the inventive device. Here, the correcting stage 11 is modeled by the element G1.

корректирующего каскада $$\text{11 Gain}=\text{0}$$

при входном напряжении $$u_{вх}=U(in)=10мВ$$

с частотой $$F(in)=10кГц$$

, а также напряжении ошибки $$u_{ош}=V4=1мВ$$

, моделирующего нелинейные искажения с частотой третьей гармоники $$\text{F(V4)}=\text{30кГц}\text{.}$$

Figure 6 shows the output voltage spectrum of the claimed device of figure 5 with a slope value $${\text{(S}}_{\text{eleven}}=\text{Gain)}$$

corrective cascade $$\text{11 gain}=\text{0}$$

at input voltage $$u_{\mathrm{at}x}=U(in)=10m\mathrm{AT}$$

with frequency $$F(in)=10\mathrm{to}Gc$$

as well as voltage errors $$u_{\mathrm{about}w}=V\mathrm{four}=\mathrm{one}m\mathrm{AT}$$

simulating nonlinear distortions with a third harmonic frequency $$\text{F (V4)}=\text{30kHz}\text{.}$$

с частотой $$F(in)=10кГц$$

, а также напряжении ошибки $$u_{ош}=V4=1мВ$$

, моделирующего нелинейные искажения с частотой третьей гармоники $$\text{F(V4)}=\text{30кГц}\text{.}$$

Сравнение фиг.6 и фиг.7 показывает, что амплитуда третьей гармоники на выходе заявляемого устройства фиг.5 уменьшилась (за счет новых связей) с 1 мВ до 2,3 мкВ, т.е. более чем в 400 раз.In Fig.7 shows the spectrum of the output voltage of the SHNU Fig.5 with a slope value S ₁₁ = Gain of the correcting stage 11S ₁₁ = Gain = 1 cm at the input voltage $$u_{\mathrm{at}x}=U(in)=10m\mathrm{AT}$$

with frequency $$F(in)=10\mathrm{to}Gc$$

as well as voltage errors $$u_{\mathrm{about}w}=V\mathrm{four}=\mathrm{one}m\mathrm{AT}$$

simulating nonlinear distortions with a third harmonic frequency $$\text{F (V4)}=\text{30kHz}\text{.}$$

A comparison of FIG. 6 and FIG. 7 shows that the amplitude of the third harmonic at the output of the inventive device of FIG. 5 has decreased (due to new connections) from 1 mV to 2.3 μV, i.e. more than 400 times.

с частотой $$F(in)=10кГц$$

, а также напряжении ошибки $$u_{ош}=V4=1мВ$$

, моделирующего нелинейные искажения с частотой третьей гармоники $$\text{F(V4)}=\text{30кГц}\text{.}$$

Данные графики показывают, что третья гармоника на выходе устройства фиг.5 уменьшилась более чем в 2000 раз.On Fig shows the spectrum of the output voltage of the SHNU figure 5 with the value of the slope of the correction stage 11S ₁₁ = Gain = 5 cm at the input voltage $$u_{\mathrm{at}x}=U(in)=10m\mathrm{AT}$$

with frequency $$F(in)=10\mathrm{to}Gc$$

as well as voltage errors $$u_{\mathrm{about}w}=V\mathrm{four}=\mathrm{one}m\mathrm{AT}$$

simulating nonlinear distortions with a third harmonic frequency $$\text{F (V4)}=\text{30kHz}\text{.}$$

These graphs show that the third harmonic at the output of the device of figure 5 has decreased by more than 2000 times.

Figure 9 shows the schematic diagram of the SNU of Figure 4 in the PSpice environment, in which the output stage 1 is implemented (to confirm the effectiveness of the claimed device) in a push-pull circuit with a knownly large deadband and has typical nonlinear distortions (Fig. 10) described in the educational literature .

Figure 10 shows the waveform of the output voltage of the device of figure 9 with a sinusoidal input signal and Gain = 0, i.e. SHNU-prototype.

In Fig.11 shows the waveform of the output voltage of the SHNU Fig.10 on an enlarged scale (Gain = 0).

On Fig presents a waveform of the output voltage of the circuit of the power cable of Fig.9 with Gain = 0.01 See

On Fig shows the waveform of the output voltage of the SHNU Fig.12 on an enlarged scale at Gain = 0.01 See

On Fig shows the waveform of Fig.13 of the output voltage of the circuit of Fig.9 on an enlarged scale at Gain = 0.1 See

On Fig shows the waveform of the output voltage of the circuit of Fig.9 with Gain = l See

On Fig presents the waveform of Fig.15 of the output voltage on an enlarged scale at Gain = 1 See. From this graph it follows that the proposed circuit solution of Fig.9 compensates for significant nonlinear distortion due to non-inverting output stage 1.

On Fig shows a diagram of the SHNU figure 4 with a deliberately large dead zone in the output non-inverting stage 1, which was used to simulate in the environment PSpice the spectrum of the output signal of the inventive device.

On Fig shows the spectrum of the output voltage of the circuit SNU Fig.17 with the value of the slope of the correction stage 11 G1 = 0 and with the input voltage u _in = U ₃ (in) = 3V with a frequency of F (in) = 10kHz. In fact, the distribution of harmonics of Fig. 18 corresponds to the properties of the SHNU prototype.

Fig. 19 shows the spectrum of the output voltage of the power supply circuit of Fig. 17 for the slope of the correction stage 11 G1 = 5 cm and the input voltage u _in = U ₃ (in) = 3V with a frequency of F (in) = 10kHz.

A comparison of the graphs of FIG. 18 and FIG. 19 shows that the amplitudes of the third, fifth and seventh harmonics in the inventive SNU circuit of FIG. 17 are reduced by more than 1000 times.

A broadband non-inverting amplifier with a low level of non-linear distortion and noise (Fig. 4) contains a non-inverting output stage 1, the input of which is connected to the input of the device 2 and the input voltage source 3 through the terminating resistor 4, the load circuit 5 connected to the output 6 of the device associated with the output of the non-inverting output stage 1. Between the input 2 and the output 6 of the device, inverted buffer amplifier 7, second 8 and third 9 additional resistors are connected in series, with the common node 10 of the second 8 and t etego 9 additional resistors connected to the input of the correction stage 11, the current output 12 which is connected to the noninverting input of the output stage 1.

In Fig. 4, in accordance with claim 2, a voltage-current converter with high input and high output resistances is used as the correcting stage 11.

In addition, in figure 4, in accordance with claim 3 of the claims, a current amplifier with low input and high output resistances can be used as a correction stage 11. In practice, a low-power and non-distorting signal buffer amplifier 7 is implemented on the basis of a cascade with sequential negative voltage feedback (Fig. 3) [16, 17].

Consider the factors that determine the level of nonlinear distortion and noise in the inventive device of figure 4, in which the unwanted spectral components due to nonlinearities in the non-inverting output stage 1 are modeled by an equivalent source of non-linear distortion u _os with a third harmonic frequency of 30 kHz.

The physical meaning of the noise suppression effect in the broadband amplifier of Fig. 4 is associated, firstly, with the allocation of an error signal u ₁₀ ~ u _os at node 10, which is proportional only to the level of undesirable spectral components u _os at the output of the non-inverting output stage 1 (in this case, frequency 30 kHz):

$$u_{10}=\frac{R_8}{R_9+R_8}{u}_{\mathrm{about}w}\approx \frac{u_{\mathrm{about}\mathrm{<figure-callout\; id="2"\; label="w"\; filenames="00000013.png,00000014.png"\; state="\{\{state\}\}">w</figure-callout>}}}{2}.$$

It should be noted that in node 10 there is no input amplified signal u _in with the considered (in this case) frequency of 10 kHz. This is due to the complete mutual subtraction at node 10 of its two antiphase components u _c = -u _in and u _out .

Dedicated thus error u ₁₀ ≈u _oui / 2 is introduced (due to the resistor 4) in the input circuit of the output stage 1 and noninverting correction stage 11 with a high output impedance and compensates for voltage u _oui generated this output stage.

Let us further consider the simulation results of Fig.6 and Fig.7. At zero slope of the signal transmission in the correcting stage 11 (S ₁₁ = G = 0), the voltage of the noise and spectral components of non-linear distortion u _{osh is} completely transmitted to load 5. This is evidenced by the ratio of the amplitudes of the harmonics at output 6 (Fig.6): output voltage with frequency of 30 kHz has an amplitude u _out = 1 mV.

With the introduction of correction circuit 11 having a slope of S ₁₁ = 1 cm, the amplitude of the output harmonic of the device of Fig. 4 with a frequency of 30 kHz decreases 500 times from 1 mV to 2.3 μV (see Fig. 7). In most cases, this suppression u _err SHNU enough for many applications. A further increase in the steepness S ₁₁ provides an even deeper attenuation of non-linear distortion and noise (Fig. 8). However, this is not always advisable. Similar conclusions can be made as a result of comparing the amplitudes of the output harmonics of the SHNU of Fig. 18 and Fig. 19 - in the proposed circuit, all spurious harmonics are reduced by more than 1000 times.

устройства в целом при малых значениях $${\vartheta }_{вых}$$

в выходном неинвертирующем каскаде 1.Thus, the claimed device has significant advantages in comparison with the prototype in the level of suppression of nonlinear distortion and noise. In addition, as the simulation shows, the proposed structure of a broadband amplifier allows you to increase the maximum slew rate of the output voltage $${\vartheta }_{\mathrm{at}sx}$$

devices in general at low values $${\vartheta }_{\mathrm{at}sx}$$

in the output non-inverting stage 1.

Information sources

1. Patent US 5.241.283 fig. 6.

2. Patent application US 2004/0080371.

3. Patent application US 2006/0132238.

4. Patent JP 1,024,2777.

5. Patent US 4.607.235.

6. Patent application US 2006/0087369 fig. 6.

7. Patent application US 2006/0220590.

8. Patent US 4.335.359.

9. Patent US 4,510.458.

10. Patent US 5.237.526 fig. 2 V.

11. Patent application US 2005/0122170.

12. Patent application US 2005/0035821.

13. Patent US 6.107.884 fig. 2.

14. Patent US 5.225.791.

15. Patent application US 2002/00057592.

16. Nonlinear active correction in precision analog microcircuits: monograph / NN Prokopenko. - Rostov-on-Don: Publishing House of the North Caucasian Scientific Center of Higher Education, 2000. - 222 p.

17. Architecture and circuitry of high-speed operational amplifiers: monograph / N.N. Prokopenko, A.S. Budyakov. - Mines: Publishing House of SRUES, 2006. - 231 p.

Claims (3)

1. A broadband non-inverting amplifier with a low level of non-linear distortion and noise, containing a non-inverting output stage (1), the input of which is connected to the input of the device (2) and the input voltage source (3) through a terminating resistor (4), a load circuit (5), connected to the output (6) of the device associated with the output of the non-inverting output stage (1), characterized in that between the input (2) and output (6) of the device are connected in series with the inverting buffer amplifier (7), the second (8) and the third ( 9) additional resistors moreover, the common node (10) of the second (8) and third (9) additional resistors is connected to the input of the correction stage (11), the current output of which (12) is connected to the input of the non-inverting output stage (1). 2. A broadband non-inverting amplifier with a low level of non-linear distortion and noise according to claim 1, characterized in that a voltage-current converter with high input and high output resistances is used as a correction stage (11). 3. A broadband non-inverting amplifier with a low level of non-linear distortion and noise according to claim 1, characterized in that a current amplifier with a low input and high output impedance is used as a correction stage (11).

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