CN203930794U - A kind of logarithm log ax computing circuit - Google Patents

Abstract

The utility model discloses a kind of general logarithm log _athe computing circuit of x.The logarithmic operational circuit existing at present only, for realizing the circuit of natural logarithm function lnx, lacks general logarithm function log _athe computing circuit of x.The utility model utilizes mathematics equivalent relation realize logarithmic function log _athe computing of x, utilize the circuit that diode D1 and integrated transporting discharging U1 form to realize the computing to the natural logarithm lnx of input function, the circuit that utilizes diode D2 and integrated transporting discharging U1 to form is realized the computing of natural logarithm lna, utilizes multiplier U2 and integrated transporting discharging U1 to realize voltage division computing, has realized log _ax logarithm operation.This utility model relates to general logarithm log _ax computing circuit, and can regulate truth of a matter a, increased the type of simulating signal computing circuit, expanded the operating range of simulating signal, it is simple in structure, and computing is accurate, good stability, the general logarithm computing that can realize simulating signal with it will have wide practical use in integrated operational amplifier circuit.

Description

A kind of logarithm log ax computing circuit

Technical field

The utility model belongs to electronic circuit field, relates to a kind of mimic channel of realizing general logarithm computing, is specifically related to a kind ofly based on natural logarithm ln x circuit and division circuit, realize general logarithm function log _ax computing circuit.

Background technology

In electronic circuit, the application of integrated transporting discharging is mainly manifested in it can form various computing circuits, by introducing voltage negative, feed back, make amplifier be operated in linear zone, and then realize the fundamental operations such as ratio, plus-minus, multiplication and division, integration, differential, logarithm and index of simulating signal.The logarithmic operational circuit existing at present (is only log for realizing natural logarithm function ln x _ex) circuit, lacks general logarithm function log _athe computing circuit of x.In order to realize general logarithm function to meet the needs of different simulating signal computings, the utility model proposes and a kind ofly can realize general logarithm function log _athe analog operational circuit of x, truth of a matter a is free value within the specific limits, can also realize log _alogarithm operations such as (sin x).

Summary of the invention

For the deficiencies in the prior art, the utility model provides a kind of general logarithm function log that realizes _ax computing circuit, utilizes natural logarithm ln x circuit and division circuit to realize general logarithm function log _ax computing circuit.

The utility model adopts following technical scheme to realize utility model object:

The utility model comprises integrated operational amplifier U1, multiplier U2, diode D1, diode D2, the 3rd pin of described integrated operational amplifier U1, the 5th pin, the 10th pin, the 12nd pin ground connection, the 4th connect+15V of pin power supply VCC, the 11st pin connects negative-15V power supply VEE; L pin connects the 2nd pin of integrated operational amplifier U1 by diode D1, connect the 9th pin of integrated operational amplifier U1 by potentiometer R5; The 7th pin connects the 6th pin of integrated operational amplifier U1 by potentiometer R4, connect the 1st pin of multiplier U2; The 8th pin connects the 3rd pin of multiplier U2; The 14th pin connects the 13rd pin of integrated operational amplifier U1 by diode D2, connect 6 pins of integrated operational amplifier U1 by potentiometer R3.

The 2nd pin of described multiplier U2, the 4th pin, the 6th pin ground connection, the 5th connect-15V of pin power supply VEE, the 8th connect+15V of pin power supply VCC; The 7th pin connects the 9th pin of integrated operational amplifier U1 by potentiometer R6.

The positive pole of described diode D1 meets input signal source x by potentiometer R1, and negative pole connects the 1st pin of integrated operational amplifier U1; The positive pole of described diode D2 connects DC power anode by adjustable sliding potentiometer, and negative pole connects the 14th pin of integrated operational amplifier U1.

The utility model utilizes natural logarithm circuit and division arithmetic circuit to realize a kind of general logarithm computing circuit, and by regulating the number percent of slide potentiometer to regulate truth of a matter a, increased the type of simulating signal computing circuit, expanded the operating range of simulating signal, it is simple in structure, and computing is accurate, good stability, the general logarithm computing that can realize simulating signal with it will have wide practical use in integrated operational amplifier circuit.

Accompanying drawing explanation

Fig. 1 is structural drawing of the present utility model.

Fig. 2 is schematic diagram of the present utility model.

Embodiment

Below in conjunction with accompanying drawing, the utility model is done further to describe in detail.

Realize function y=log _athe computing of x, according to mathematical relation

$y={\log }_{a}x=\frac{\ln x}{\ln a}---a$

As long as realize computing.As shown in Figure 1, the circuit that utilizes diode D1 and integrated transporting discharging U1 to form is realized the computing of ln x; The circuit that utilizes diode D2 and integrated transporting discharging U1 to form is realized the computing of ln a; Utilize multiplier U2 and integrated transporting discharging U1 to form division circuit, realize computing, realizes log _ax logarithm operation.

As shown in Figure 2, the electric current of diode D1 and voltage:

$i_{D1}=I_S{e}^{v_{D1}/V_T},v_{D1}=V_T\ln \frac{I_S}{i_{D1}}=V_T\ln \frac{x}{i_{D1}{R}_1}---b$

The output voltage of integrated transporting discharging U1 pin 1:

$v_1=-v_{D1}=-V_T\ln \frac{I_S}{i_{D1}}=-V_T\ln \frac{x}{i_{D1}{R}_1}---c$

Same, the electric current of diode D2 and voltage:

$i_{D2}=I_S{e}^{v_{D2}/V_T},v_{D2}=V_T\ln \frac{I_S}{i_{D2}}=V_T\ln \frac{x}{i_{D2}{R}_2}---d$

The output voltage of integrated transporting discharging U1 pin 14:

$v_2=-v_{D2}=-V_T\ln \frac{I_S}{i_{D2}}=-V_T\ln \frac{x}{i_{D2}{R}_2}---e$

After the inverting amplifier that this voltage forms through R3, R4 and the 5th pin, the 6th pin and the 7th pin amplifies, at the output voltage of the 7th pin, be:

$v_3=\frac{R_4}{R_3}{V}_T\ln \frac{V}{i_{D2}{R}_2}---f$ The output of the 8th pin of this input voltage and integrated transporting discharging U1 is added in the 1st pin and the 3rd pin of multiplier U2, jointly form divider with the 8th pin, the 9th pin, the 10th pin of integrated transporting discharging, realize division arithmetic, at the 8th pin output voltage of integrated transporting discharging:

$v_4=-\frac{R_5}{R_6}\frac{v_1}{v_3}=\frac{R_5}{R_6}\frac{R_3}{R_4}\frac{\ln \frac{x}{i_{D1}{R}_1}}{\ln \frac{V}{i_{D2}{R}_2}}=\frac{\ln x}{\ln a}={\log }_{a}x---g$

At this, get i _d1r ₁=1, there is v ₄=log _ax.

Described a kind of logarithmic function log _athe computing circuit of x, by integrated operational amplifier U1, multiplier U2, diode D1, diode D2, formed, integrated operational amplifier U1 realizes conversion, amplification, the negative function of signal, diode D1 and integrated operational amplifier U1 realize input function x are asked to natural logarithm computing ln x, diode D2 and integrated operational amplifier U1 realize natural logarithm calculation function ln a, multiplier U2 and operational amplifier U1 realize the division arithmetic function of two signal ln x and ln a, realize logarithmic function calculation function.

The 3rd pin of described integrated operational amplifier U1, the 5th pin, the 10th pin, the 12nd pin ground connection, the 4th connect+15V of pin power supply VCC, the 11st pin connects negative-15V power supply VEE; L pin connects the 2nd pin of integrated operational amplifier U1 by diode D1, connect the 9th pin of integrated operational amplifier U1 by potentiometer R5; The 7th pin connects the 6th pin of integrated operational amplifier U1 by potentiometer R4, connect the 1st pin of multiplier U2; The 8th pin connects the 3rd pin of multiplier U2; The 14th pin connects the 13rd pin of integrated operational amplifier U1 by diode D2, connect 6 pins of integrated operational amplifier U1 by potentiometer R3.

The 2nd pin of described multiplier U2, the 4th pin, the 6th pin ground connection, the 5th connect-15V of pin power supply VEE, the 8th connect+15V of pin power supply VCC; The 7th pin connects the 9th pin of integrated operational amplifier U1 by potentiometer R6.

The positive pole of described diode D1 meets input signal source x by potentiometer R1, and negative pole connects the 1st pin of integrated operational amplifier U1.

The positive pole of described diode D2 connects DC power anode by adjustable sliding potentiometer, and negative pole connects the 14th pin of integrated operational amplifier U1.

The utility model has been realized a kind of general logarithm computing circuit, increased the type of simulating signal computing circuit, expanded the operating range of simulating signal, it is simple in structure, computing is accurate, good stability, the general logarithm computing that can realize simulating signal with it will have wide practical use in integrated operational amplifier circuit.

Certainly, above-mentioned explanation is the restriction to utility model not, and the utility model is also not limited only to above-mentioned giving an example, and the variation that those skilled in the art make in essential scope of the present utility model, remodeling, interpolation or replacement, as log _alogarithm operations such as (sin x) also belongs to protection domain of the present utility model.

Claims (1)

1. a logarithmic function log _athe computing circuit of x, comprise integrated operational amplifier U1, multiplier U2, diode D1, diode D2, it is characterized in that: the 3rd pin of described integrated operational amplifier U1, the 5th pin, the 10th pin, the 12nd pin ground connection, the 4th connect+15V of pin power supply VCC, the 11st pin connects negative-15V power supply VEE; L pin connects the 2nd pin of integrated operational amplifier U1 by diode D1, connect the 9th pin of integrated operational amplifier U1 by potentiometer R5; The 7th pin connects the 6th pin of integrated operational amplifier U1 by potentiometer R4, connect the 1st pin of multiplier U2; The 8th pin connects the 3rd pin of multiplier U2; The 14th pin connects the 13rd pin of integrated operational amplifier U1 by diode D2, connect 6 pins of integrated operational amplifier U1 by potentiometer R3;

The 2nd pin of described multiplier U2, the 4th pin, the 6th pin ground connection, the 5th connect-15V of pin power supply VEE, the 8th connect+15V of pin power supply VCC; The 7th pin connects the 9th pin of integrated operational amplifier U1 by potentiometer R6;

The positive pole of described diode D1 meets input signal source x by potentiometer R1, and negative pole connects the 1st pin of integrated operational amplifier U1; The positive pole of described diode D2 connects DC power anode by adjustable sliding potentiometer, and negative pole connects the 14th pin of integrated operational amplifier U1.