SU1615754A1 - Square voltage to frequency converter - Google Patents

Abstract

The invention relates to devices for converting electrical signals according to quadratic law and can be used in analog computers. The aim of the invention is to increase reliability. The quadratic voltage-to-frequency converter contains a bipolar current source 1, a switch 2, an integrating capacitor 3, an operational amplifier 4, the first and second scale resistors 5, 6, a voltage follower 7, a junction capacitor 8, the third and fourth scale resistors 9, 10 , zero potential bus 11, input 12, output 13. The operation of the device is based on integrating the sum of the input slowly varying voltage and high frequency voltage due to the charge of the integrating capacitor 3 with the current of source 1. 2 Il.

Description

O5

: l

SP

four

The invention relates to a device intended for quadratic conversion of electrical power rails and can be used in analog computing machines.

The purpose of the invention is to increase reliability.

Fig. 1 shows a functional diagram of a quadratic voltage-to-frequency converter: in Fig. 2, signal timing diagrams.

The circuit contains a bipolar current source 1, a switch 2, an integrating capacitor 3, an operational amplifier 4, the first second scale resistors 5 and 6, a voltage follower 7, a coupling capacitor 8, the third and fourth scale resistors. 9 and 10, bus 11 zero potential, input 12, output 13.

The device works as follows.

Suppose there is no input voltage 12. Let the threshold voltage of negative polarity be applied to the input of the threshold element formed by 1 operational amplifier 4 and the first and: the second large-scale resistors 5 and 6, and switch 2 is in the position shown in FIG. 1; The integrating capacitor is 3 with a constant current of a two-field current source 1. The voltage at the input of the voltage follower 7 (FIG. 26) varies linearly (the charge is direct current) until the voltage is equal to the threshold level. At the time of the voltage equal to the voltage threshold, the threshold element is triggered. As a result, the polarity of the threshold voltage changes, and the switch 2 is shifted to the opposite position shown in FIG. 1. The process of recharging and repeater of the capacitor 3 with current from another output of two polarity current source 1 occurs, while the input voltage of the repeater 7 the voltage also varies linearly, but in the opposite direction until it is equal to the threshold voltage, B is the moment of equality again ... the threshold element is triggered, changing 1. The polarity of the threshold voltage and Turn off switch 2.

Where

T-6

and,

Then the cycle of operation is repeated. Thus, the cycle of operation consists of Vuh cycles, in the first cycle switch 2 is in the lower position, the threshold voltage is negative, in the second cycle switch 2 is in the upper position1, the threshold voltage is positive.

The pulse frequency at output 13 in the absence of voltage at input 12 is the initial frequency and is determined by the expression

f. about 4UnC

current bipolar1 of current source 1;

threshold voltage at the non-inverting input of op amp 1; C is the capacitance of the integrating capacitor 3.

Let the input voltage 12 be an alternating voltage (Fig. 2a). Followed; Equality of potentials at the inverter and the non-inverting inputs of the operational amplifier 4. On the integrating capacitor 3 there is a component voltage that is proportional to the voltage at the input 12,

At the input of the voltage follower 7, the integrated input voltage and sawtooth voltage (Fig. 2c), formed by the charge of the integrating capacitor 3 by the reference current, are summed up. Otherwise, the operation does not differ from operation in the absence of voltage at input 12. The frequency of the pulses at output 13 (Fig. 2d) in the presence of voltage at input 12 is described by the expression

f fo-SU |,

where S is the conversion factor; and) (- input voltage 12, the conversion factor is equal to

one

  4U i; TR; R4) C

where R ,, R is the resistance values of the third and fourth scale resistors 9 and 10.

To integrate the voltage from the input 12 and the reference currents of the two-pole current source 1, only the integrating capacitor 3 is used. To ensure the linear integration of the currents and the voltage by the same integrating capacitor 3, a combination of the voltage follower 7 and the isolating capacitor 8 is used. input 12 is integrated linearly with a constant integration defined by integrating capacitor 3 and the sum of the third and fourth scaling resistors 9 and 10 that integrate shunt This capacitor 3. This is achieved by a voltage follower 7 and a coupling capacitor 8. Only the high-frequency component of the signal present on the first plate of the integrating capacitor 3 passes through the coupling capacitor 8 (FIG. 2). This component is sawtooth the result of integrating different - polar currents). Thus, at the junction point of the coupling capacitor 8 and the third and fourth scale resistors 9 and 10, this sawtooth voltage is present (Fig. 2c). Equal potentials arising on the first plate of the integrating capacitor 3 and at the specified junction point of the coupling capacitor 8 exclude the possibility of branching currents into the circuit formed by the third and fourth large-scale resistors 9 and 10, which ensures linear integration of the currents.

I

Claims (1)

Invention Formula Quadratic converter of the national to the frequency containing two ten 15754 The primary reference current source, the first and second outputs of which are connected to the inputs of a switch, the output of which is connected to the inverting input of an operational amplifier, the output of which is connected to the control input of a switch and the output of the converter, the first terminals of the first and second large-scale resistors are connected to a non-inverting input an operational amplifier, the output of which is connected to the second step of the second large-scale resistor, a voltage follower, the output of which is connected to the first plate of the separator a capacitor integrating a capacitor, the first plate of which is connected to the input of a voltage follower, a third large-scale resistor, characterized in that, in order to increase reliability, a fourth large-scale resistor is inserted into it, the first output of which is connected to the input of the repeater, voltage, the second output the fourth scale resistor is connected to the first output of the third scale resistor and to the second plate of the coupling capacitor, the inverting input of the operational amplifier is connected to the input of the repeater, eg The second plate of the integrating capacitor and the second output of the third scale resistor are connected to the zero potential bus; the second output of the first scale resistor is the input of the converter. 15 20 25 thirty 35