SU758183A1 - Device for inversely proportional conversion of dc voltage - Google Patents

Description

The invention relates to electrical computing devices and can be used in analog computers.

The known device designed to calculate the ratio of the two voltages, which contain a controlled current generator, an operational amplifier, between the input and output of which are connected counter-connected logarithmic diodes (1). , θ

However, this device performs voltage conversion in a narrow range of their values.

The closest to the proposed is a device for inversely proportional DC voltage conversion, containing an operational amplifier, the input and output of which are connected to the same-name electrodes of the first and second logarithmic diodes, respectively, whose other electrodes of the same name are connected to the output of a controlled current generator, whose input is connected to the input of the input voltage source to the input of the operational amplifier plug 2

waters of the current-carrying resistor, generator of sinusoidal voltage [2].

A disadvantage of this device is the limited conversion range. The magnitude of the conversion range (for a given conversion accuracy) is determined by the degree of matching of logarithmic diodes, the variation of which leads to a deviation of the output voltage of the device from the desired value and the greater, the wider the range of the input voltage.

The purpose of the invention is the expansion of the input voltage.

This goal is achieved by the fact that an additional current-carrying resistor, a differentiator and an amplitude meter are entered into the device, the sinusoidal voltage generator output is connected to the second current-setting resistor output, the output-source voltage input is connected via an additional current-carrying resistor to the input of the operational amplifier, the output of which is connected through the differentiator ! to meter input amnln3 758183

This is the output of the device.

The drawing shows a functional diagram of the proposed device for inversely proportional conversion of DC voltage.

The device includes a sinusoidal voltage generator 1, an input voltage source 2, a current setting resistor 3, an additional current setting resistor 4, an operational amplifier 5, the first and second logarithmic diodes 6 and 7, a controlled current generator 8, a differentiator 9, an amplitude meter 10 and an output 11 of the device .

The device works as follows. and

The input potential of the operational amplifier 5 is zero due to negative feedback through the first and second logarithmic diodes 6 and 7. Therefore, the direct current flowing through the first logarithm diode 6, 20 is proportional to the input voltage from the input voltage source 2, and inversely proportional to the additional resistance current-setting resistor 4. Similarly, the amplitude of the alternating current through 25 the first logarithmic diode 6 is determined by the amplitude of the signal coming from the generator 1 sine Further voltage, resistance and voltage driving resistor 3.

The parameters of the controlled generator 8 of the current are selected so that its output current (proportional to the input voltage) is twice the direct current specified in the first logarithm diode 6. Therefore, the direct current through the second logarithm is equal to the direct current through the first logarithm diode 6 ..

Since the first and second logarithmic diodes 6 and 7 are turned on counter, the alternating currents flowing through them are the same in amplitude, but opposite in phase. If at the moment the total current of the first logarithmic diode 6 increases, then the total current of the second logarithmic 45 diode 7 decreases by the same amount, and the sum of these currents remains constant and equal to the output current of the controlled current generator 8.

The output AC voltage of the operational amplifier 5 is equal to the difference of the alternating voltages on the first and second logarithmic diodes 6 and 7, therefore it does not contain even harmonics of the fundamental frequency of the sinusoidal signal, since the sign of the even harmonics does not change when the signal phase changes and when _{e5 turns} on the first and second logarithmic diodes 6 and 7 even harmonics are mutually subtracted. On the contrary, odd harmonics (including the fundamental frequency) of 4

change their sign and therefore add up at the output of the operational amplifier 5.

As a result, the output AC voltage '· _d, and of the operational amplifier 5 has a spectral composition defined by the Fourier series expansion

C 5 5

^and d = 4φ _τ (Ε5ίηωί - ξ ₅ ΐη3ωί + Е ₅ ίπ5ωί -...)

⁵ (1)

where ν> _τ is the temperature potential of logarithmic diodes 6 and 7.

where ω - circular frequency generator 1 sinusoidal signal;

ί · - time;

3 ₅ ¹¹ ~ constant and variable

currents flowing through the first logarithm diode 6.

This alternating voltage is supplied to the differentiator 9, which increases the amplitude of each harmonic in proportion to its number.

After differentiation, an alternating voltage is supplied to the input of the 10 amplitude gauge and ^, having a spectrum

Ό _η = 4ω <ρ _τ (Ρεο5ω Т - Р ^э соЗЗЛЛ + Р ⁵ co5бЛЛ ...) (2) The amplitudes of the spectral components quickly decrease with increasing harmonic number, therefore the voltage amplitude А ^ is equal to the algebraic sum of the amplitudes of the individual harmonics

Α _η = 4ω <ρ _τ (Ρ - Р ³ + Р ⁵ - Р ⁷ + ...) (3)

Given the value of P, it is easy to show that

Α _η = 2ω ^ _τ 3 _ρ : 3 ₈ . (four)

Thus, the amplitude of the alternating voltage at the output of the differentiator 3 back. It is proportional to the direct current 3 _$ , flowing through the logarithmic diodes 6 and 7, and inversely proportional to the value of the constant input voltage.

The amplitude of the voltage at the Output of the differentiator 9 is measured by the meter ¹ 10 amplitude (for example, peak detector), the output DC voltage of which is inversely proportional to the input DC voltage of the entire device.

The proposed device contains only two logarithmic diodes, so it is easier to harmonize their characteristics. In particular, the equality of the reverse currents of the first and second logarithmic diodes 6 and 7 is not required, since the reverse currents only change

five

758183

a constant component of the output voltage of the operational amplifier 5. This expands the conversion range in comparison with the known device, which contains four logarithm diodes and allows you to more fully use the working section of the characteristics of logarithm diodes 6 and 7.

The proposed device allows you to implement the conversion range from 100 mV to 10 V with a conversion error not exceeding 1%.

Claims (1)

Claim A device for inversely proportional DC voltage conversion, containing an operational amplifier, the input and output of which are connected to the same-name electrodes of the first and second logarithmic diodes, respectively, the other of which of the same name are connected to the output of a controlled current generator, whose input connected to the output of the input voltage source, to the input of the operational amplifier connected to the output of the current-supplying resistor, a sinusoidal voltage generator, about ₅ and ₅ , in order to expand the range of the input voltage, an additional current-providing resistor, differentiator and amplitude meter, the output of the sinusoidal voltage generator is connected to the second output of the current-setting resistor, the output of the input voltage source is connected via an additional resistor to the input of the operating voltage amplifier, the output of which through the differentiator is connected to the input of the amplitude meter, the output of which is the output of the device.