阅读说明：本技术 一种适用于收发合置换能器的低噪声初级放大电路及噪声分解方法 (Low-noise primary amplifying circuit suitable for transmitting-receiving combined energy-replacing device and noise decomposition method ) 是由 彭阳明 杭亮 徐春秋 于 2019-10-16 设计创作，主要内容包括：本发明公开了一种适用于收发合置换能器的低噪声初级放大电路及噪声分解方法,主要包括收发转换模块、滤波模块、运算放大电路,收发转换模块设有保护二极管对D1、D2、D3、D4,以及电阻R4和功率电感L,滤波模块包括电阻R1、电容C,与功率电感构成带通滤波,运算放大电路由低电压、电流噪声运放及电阻R2、R3构成。本发明用功率电感替代收发转换模块的功率电阻,调整优化放大电路输入端RC滤波参数,从而消除原电路中功率电阻对放大电路噪声、信号接收效率的影响；可用于主动声纳回波信号的低噪声放大及电路噪声量级评估；提高了信号接收效率；建立了噪声计算模型,验证了电路设计正确性,可指导同类型电路设计。(The invention discloses a low-noise primary amplifying circuit suitable for a transmitting-receiving combined energy-replacing device and a noise decomposition method, and the low-noise primary amplifying circuit mainly comprises a transmitting-receiving conversion module, a filtering module and an operational amplifying circuit, wherein the transmitting-receiving conversion module is provided with protection diode pairs D1, D2, D3 and D4, a resistor R4 and a power inductor L, the filtering module comprises a resistor R1 and a capacitor C, and forms band-pass filtering with the power inductor, and the operational amplifying circuit comprises a low-voltage and current noise operational amplifier and resistors R2 and R3. The power inductor is used for replacing the power resistor of the transceiving conversion module, and the RC filter parameter of the input end of the optimized amplifying circuit is adjusted, so that the influence of the power resistor in the original circuit on the noise and the signal receiving efficiency of the amplifying circuit is eliminated; the method can be used for low-noise amplification and circuit noise magnitude evaluation of the active sonar echo signals; the signal receiving efficiency is improved; a noise calculation model is established, the circuit design correctness is verified, and the same type of circuit design can be guided.)

1. A low-noise primary amplifying circuit suitable for a transmitting-receiving combined energy-replacing device is characterized in that: the high-power-consumption low-voltage operational amplifier mainly comprises a transceiving conversion module, a filtering module and an operational amplifier circuit, wherein the transceiving conversion module is provided with a protection diode pair D1, D2, D3 and D4, a resistor R4 and a power inductor L, the filtering module comprises a resistor R1 and a capacitor C, the power inductor and the resistor R4 form band-pass filtering, and the operational amplifier circuit comprises a low-voltage operational amplifier, a current noise operational amplifier and resistors R2 and R3.

2. The low noise primary amplification circuit of claim 1, wherein: the inductive reactance of the power inductor is far larger than the impedance of the transducer array and is approximately equal to the resistance value of the replaced power resistor, namely

ω₀L≈R_w

Wherein ω is₀Representing the sonar operating angular frequency; l represents a power inductance value; r_wRepresenting the power resistor resistance.

3. The low noise primary amplification circuit of claim 1, wherein: the resistance value of R1 is far greater than the impedance of the transducer, the bandwidth of the amplifying circuit is greater than the sonar working bandwidth, the low-frequency interference of the input end is restrained, and the calculation formula of the bandwidth of the input end of the circuit is as follows:

wherein ω is₀Representing the sonar operating angular frequency; f. of₀Representing the operating frequency of the sonar; q represents the circuit quality factor, L represents the power inductance value; r₁The resistance value of the filter resistor at the input end is shown, and the capacitance value of the filter capacitor is shown by C.

4. The low noise primary amplification circuit of claim 1, wherein: the resistance requirement of the resistor R4 is far larger than the series resistance of R1 and C.

5. A noise decomposition method using a low-noise primary amplification circuit suitable for a transmit-receive switching power converter is characterized in that: the equivalent input noise model of the low-noise primary amplifying circuit decomposes circuit noise into five parts and provides a corresponding calculation method, which mainly comprises the following steps:

1) amplifying the chip voltage noise Vn;

2) amplifying a current noise Vireq1 generated by the chip current noise In flowing through the equivalent impedance Zreq1 at the positive input end;

3) amplifying the current noise Vireq2 generated by the chip current noise In flowing through the equivalent resistor Rreq2 at the negative input end;

4) the thermal noise of the positive input terminal resistor R1 is equivalent to the noise value Vnreq1 of the input terminal;

5) the thermal noise Vnreq2 generated by the equivalent resistance Rreq2 at the negative input end;

wherein, Rreq1 ═ R1// Rw; rreq2 ═ R2// R3.

6. The method of claim 5, wherein the noise cancellation scheme comprises: the noise spectrum calculation formula is as follows:

wherein k is Boltzmann constant, and k is 1.38 × 10^-23J/K; the temperature T is absolute temperature, such that:

V_ireq1＝I_n·Rreq1；V_ireq2＝I_n·Rreq2；

by selecting low-voltage and low-current noise chips, Vn, Vireq1 and Vireq2 are far smaller than Vnreq1, feedback circuit resistors R2 and R3 are reasonably set, and Vnreq2 is far smaller than Vnreq1, so that:

V_total≈V_nreq1

r1 is far greater than Rw, Rreq1 is approximately equal to Rw, and the main circuit noise is power resistance thermal noise.

Technical Field

The invention relates to the field of active sonar signal receiving circuits, in particular to a low-noise primary amplifying circuit and a noise decomposition method suitable for a transmitting-receiving combined energy-replacing device.

Background

As can be seen from the fries formula, each stage of the cascade amplifier circuit has different influences on noise, and the influence is larger as the stage is the earlier stage. When the amplification factor of the primary amplification circuit is sufficiently large, the total noise of the system depends on the noise of the primary amplification circuit. Therefore, low noise design of the primary amplification circuit is crucial.

When the transmitter and the receiver share one transducer array, a transceiving conversion module is needed, so that the receiver is prevented from being damaged by high-power signals during transmission and normally receives echoes during reception. The widely used receiving and transmitting conversion module is connected with a power resistor in series at the front end of a primary amplifying circuit, and has the advantages of simple and reliable circuit and strong anti-interference capability. The advantage is that in order to reduce the influence of the power resistor on the transmission efficiency, the required resistance value is far larger than the impedance of the transducer, when the impedance of the transducer is larger, the thermal noise of the power resistor is far larger than other noises, and becomes the main noise source of the primary amplifying circuit, and the resistor R in the RC filter circuit at the input end of the amplifying circuit form a voltage dividing circuit, so that the receiving efficiency of the circuit is reduced, and the voltage dividing circuit becomes an important factor for limiting the acting distance of the sonar equipment.

Disclosure of Invention

The present invention is directed to overcome the deficiencies of the prior art and to provide a low noise primary amplifier circuit and a noise decomposition method suitable for a duplexer.

The purpose of the invention is achieved by the following technical scheme: the low-noise primary amplifying circuit suitable for the transmitting-receiving combined energy-replacing device mainly comprises a transmitting-receiving conversion module, a filtering module and an operational amplifying circuit, wherein the transmitting-receiving conversion module is provided with protection diode pairs D1, D2, D3 and D4, a resistor R4 and a power inductor L, the filtering module comprises a resistor R1 and a capacitor C, band-pass filtering is formed by the resistor R1 and the capacitor C and the power inductor, and the operational amplifying circuit is formed by a low-voltage and current noise operational amplifier, a resistor R2 and a resistor R3.

The equivalent input noise model of the low-noise primary amplifying circuit decomposes circuit noise into five parts and provides a corresponding calculation method, which mainly comprises the following steps:

1) amplifying the chip voltage noise Vn;

2) amplifying a current noise Vireq1 generated by the chip current noise In flowing through the equivalent impedance Zreq1 at the positive input end;

3) amplifying the current noise Vireq2 generated by the chip current noise In flowing through the equivalent resistor Rreq2 at the negative input end;

4) the thermal noise of the positive input terminal resistor R1 is equivalent to the noise value Vnreq1 of the input terminal;

5) the negative input equivalent resistance Rreq2 generates thermal noise Vnreq 2.

The invention has the beneficial effects that: the power inductor is used for replacing the power resistor of the transceiving conversion module, and the RC filter parameter of the input end of the optimized amplifying circuit is adjusted, so that the influence of the power resistor in the original circuit on the noise and the signal receiving efficiency of the amplifying circuit is eliminated; the method can be used for low-noise amplification and circuit noise magnitude evaluation of the active sonar echo signals; the influence of current noise and power resistance thermal noise of the positive input end of the amplification chip is eliminated, and the circuit noise of the primary amplification circuit is reduced; the signal receiving efficiency is improved; a noise calculation model is established, the circuit design correctness is verified, and the same type of circuit design can be guided; the method can be widely applied to a transducer preamplifier circuit of a transmitting and receiving combined device.

Drawings

Fig. 1 is a schematic diagram of a general primary amplifying circuit for transmitting and receiving a combined sonar.

Fig. 2 is a schematic diagram of an equivalent input noise model of a general primary amplification circuit.

Fig. 3 is a schematic diagram of the principle of the present invention.

FIG. 4 is a schematic diagram of an equivalent input noise model of the present invention.

Detailed Description

The invention will be described in detail below with reference to the following drawings: