SU1226350A1 - Apparatus for measuring non-linearity of sawtooth voltage - Google Patents

Abstract

The invention relates to measuring the parameters of pulsed signals and can be used to measure the maximum (integral) nonlinearity coefficient of sawtooth voltages in a wide range of variations in their amplitudes and lengths of cells. The invention extends the dynamic range of monitored voltage converters by eliminating the effect of differentiating the initial sawtooth voltage on the dynamic range of the input sawtooth voltage. This is achieved by introducing into the device a dividing unit 11, switches 12 and 13, a source of the reference voltage 15 and a gate driver 14. The device also contains a differentiating stage 1, a generator of 2 pulses of adjustable duration, a generator of 3-step voltage, comparator. prohibition element 5, the pulse counter 6, the display unit 7, the amplitude detector 8, the block 9 of the vertex inflection, and the detector Yu of the sign.2il, Oy (L Figure 1

Description

one

The invention relates to the technique of measuring the parameters of pulsed signals, is intended to measure the integral (highest) value of the nonlinearity coefficient (CN) of sawtooth voltages in a wide range of variations in their amplitudes and durations and can be used in devices for monitoring parameters of sawtooth voltage generators for various purposes.

The purpose of the invention is to expand the dynamic range of monitored voltage converters by eliminating the influence of the operation of differentiating the original sawtooth voltage on the dynamic range of the input sawtooth voltage.

Fig, 1 shows a structural diagram of the proposed device; FIG. 2 shows the time diagrams, as shown in his work.

The device contains a differentiating cascade 1, an input connected to the measuring input of the device, a generator of 2 pulses of adjustable duration, an input connected to the synchronization input of the device, a generator of 3 stepped voltage, a comparator 4 prohibition element 5, a pulse counter 6, a display unit 7 connected between cascade, with the control input of the generator 3 of the step voltage connected to the synchronization input of the device and the second input of the prohibition element 5 is connected to the output of the generator 2 pulses of adjustable duration lnosti and amplitude detector 8 and 9 block of the selected vertices., one input of which is connected to opor- Nome entry generator 3 stepwise. voltage, and output.connected to the input of the comparator 4 and through the detector 10 nonlinearity sign to the block 7 indicator 7 of the division block 11, connected by a divide input to the output of the differentiating stage 1, switches 12 and 13, the gate pulse generator 14 and the source 15 of the reference voltage, the output of the switch 12 sos, d.nen with the input of the divider unit 11, one input of the switch 12 of St. A voltage source with a reference voltage source 15, a 3-step voltage generator reference input and a dividing block 11 scale input, its output is connected to the input of switch 13, one output; which is connected to the second input of block 263502

9 of the laziness of the apex, and the second output of the switch 1.3 is connected via an amplitude detector to the second input of the switch 12 The strobe pulse shaper 14 5 is connected to the device sync input by the input and connected to the control inputs of the switches 12 and 13 on the output generator 3 step voltage and the third input element 5 of the ban.

The device works as follows.

Before entering to its inputs, a sawtooth voltage Uf, and clock pulses U (; 5 setting the repetition rate: GF voltage, are equal to zero, the output voltages U, U, and, respectively, the generator 2, 20 of the Counter b and the driver 14, and the switches 12 and 13 are in the upper position, due to which the input (divider of unit 11 is supplied with voltage Tsf equal to voltage II, d of source 1.5, the current I.Ct is also equal to zero) at the input of divisible unit 11, therefore the initial the values of the voltages Ug Ug - 0. The output voltage Uj is the block KSI 9 distribution of the v. peak corresponds to the upper limit of its dynamic range (Fig 2), the comparator 4 is J5. states 1, and the element 5, for: is oriented to the zero-pass voltage level, and

thirty

45

35

The measurement cycle of the QN begins with the appearance of the inputs and the tul-COS voltages U, and U, and is realized in two thirds of action, one of which is preparative and the other measuring. In the first (preparatory) cycle, the duration of which is equal to Tj (FIG. 2), the front 0-1 of the first clock pulse U actuates the strobe-puller 14 strobe-pulse, which forms a strobe-pulse, the leading edge of which is delayed by time T with respect to front of synchronization pulse Ug block. At the output of the differential cascade 1, current pulses appear) proportional to the values of the sawtooth voltage derivative. They are converted by a block 11 divisions into pulses - napr-55 zhen. rectangular shape (FIG. 2), the amplitude of the pulses is proportional to the maximum slew rate (derivative) of the pigs

neither, and the decay of the peak corresponds to the variation of this speed characterizes the non-linearity of the saw-tooth voltage during forward travel. The pulses come through the switch 13 to the input of the amplitude detector 8. Because of the inertia of the latter, which contains the storage capacitor, a transient process appears, setting the gain factor Cc,). The first input of the vertex extraction unit 9 receives a constant voltage from their subtraction and subsequent amplification at the output of block 9 during the forward stroke of the saw-tooth voltage, the top of the pulses are formed.

Their amplitude is proportional to the intensity of the voltage U (Fig. 2). By the time the th integral value of f KN, and the coefficient of the end of the preparatory .t. After time T ,, the transient process of the amplitude detector 8 must be completely completed, and the output voltage of the detector 8 should be set to a constant voltage level equal to the amplitude value of the signal U2. The duration of the second (measuring) clock is set by the time of action Tj-T, the gate-pulse U (Fig. 2). At the beginning of the clock cycle, the positive voltage drop U of the strobe pulse orients switches 12 and 13 to the lower position, unlocks the 3-stage voltage generator, and gives permission to switch the prohibition element 5 into the pass-through state. The output of the amplitude detector 8 through the switch 12 with the input of the divider unit 11, as a result of which the input voltage is set at this input

four

IL and current I

Affairs

35

proportional to the maximum derivative of the sawtooth voltage, and a pulse voltage U appears at the output of dividing unit 11.

The parameters of the pulses Uj in the second cycle Do not depend on the input resistances of the dividing unit 11, on the parameters of the differentiating cascade and their changes caused by temperature and time effects. This contributes to an increase in the measurement accuracy of the CL. In addition, the amplitude of the pulses does not depend on the rate of increase of the sawtooth voltage and, therefore, on the amplitude and duration of the controlled sawtooth voltage. For all measurements, it remains equal to the voltage of the source-50 and 15 (Fig. 2).

The decay of the apex of pulses U at the output of dividing unit 11 corresponds to the magnitude of the VF of the sawtooth voltage. The pulse voltage L. through the switch 55 is fed to the second input of the vertex extraction unit 9 (differential amplifier with step-adjustable

263504

the gain factor Cr,). At the first input of the vertex extraction unit 9, a constant voltage is applied from the source 15. As a result of their subtraction and subsequent amplification, the output of the block 9 during the forward stroke of the sawtooth voltage is generated by the vertex pulses.

Their amplitude is proportional to the infection of proportionality is a constant factor, the value of which is given by the stable values of U, and Kyj.

The latter is selected from the ratio

TO,

 1 / H

maize

5 0 5 Q

five

0

Where

, is the maximum value of the measured nonlinearity in relative units,

So, with a maximum nonlinearity of 0.1, the value of K, .р 10, and 0.01, K is 100. Since the range of measured values of QN is divided into several subranges in the proposed device, Km also has several fixed values. In this case, the switching of the range of measured nonlinearity of the sawtooth voltage is carried out by a stepwise change in the value of K.

In order to balance the amplitude of the pulses of the apex, an auxiliary step voltage U (Fig. 2) is formed, each step of which is generated synchronously with the front 0-1 of the pulses Uf. The size of each step of the voltage U does not depend on the parameters of the controlled saw-tooth voltage, i.e. for all measurements, it remains constant. It is equal to 1% of the value of the stable voltage and f (5 of the source 15 (in Fig. 2, the step size is shown on an enlarged scale).

In order to obtain an auxiliary voltage, the reference input of the 3-step voltage generator is connected to the source 15. Thus, a change in the voltage on the reference input of the 3-step voltage generator is eliminated, due to which the proposed device removes the limitations imposed by the 3-step voltage generator on the value of the sawtooth voltage dynamic range, which limit the dynamic range of the controlled sawtooth voltage to relatively small values ( ka 3 ,,., .a),

From the generator output 3 of the step voltage, the voltage Ug goes to one input of the comparator 4, where it is compared with the pulses of the vertex U arriving at the other input of the comparator 4 from the output of block 9. While the output voltage U of the comparator 4 is equal to logical zero, and for logic unit. Overvoltages U-. J formed at the moments of changing the sign of the difference, serve as fronts of positive-negative comparison pulses of comparator 4. They arrive at the first input of prohibition element 5, which is in a non-throughput state. At the second input of the element 5 of the ban, the output pulses Ug are received from the generator 2 pulses of a regulated duration. Cut 1-0 first after the start of the measuring pulse Ug sets the prohibition element 5 into the throughput state. A half-pulse comparison of the first step of the voltage Ug with its Uj-., Formed by the block 4, forms the output 1 of the prohibition 5 0 voltage Ug (Fig 2) g is recorded by the counter 6 t-; further display unit 7

Subsequently, the compensating voltage Ug increases stepwise, and the counter 6 counts the comparison pulse occurring during the forward running of the sawtooth voltage — HPIK. Comparison pulses 5 arriving at the time of the reverse sawing voltage of the sawtooth voltage do not pass to the input of counter 6, since at this time the prohibition element 5 is blocked by a pulse U, j from generator 2, the minimum duration of a bit exceeds the duration of the return stroke of the sawtooth voltage. Therefore, as soon as the compensating voltage Ug becomes greater than the amplitude and at the pulse peak, the access of the comparison pulses to the input of the counter 6 stops, B its bits and in block 7 and the dicate is fixed - KiifM dB is a code of the number N for which you can write the equation

 and ,,,, |, „N, whence

N lOO Ky.t

Thus, the measurement result generated at the second cycle is the number N equal to the integral (highest) value JCH of the controlled sawtooth, expressed directly in percent. The display unit 7 displays the measurement result in decimal code.

To measure the non-linearity in a separately selected section of the forward stroke of the saw-tooth voltage, it is necessary and: to change the pulse duration Ug J, which is illustrated in Fig. 2 by dashed lines.

The sign detector 10 differentiates and amplifies the signal U from the output of the 9 aperture block 9. At the output of the detector 10, a logical zero level is set at a positive KN sign and a logical one level, when the KN sign is negative. The signals from the output of the detector 10 control the operation of the corresponding indicator in block 7, for example, an LED.

Cut-off the strobe pulse U, the second (measuring) operation cycle of the device is completed, as well as the CL change cycle. The voltage drop U to the logic zero level returns switches 12 and 13 (FIG. 1) to the upper position 5 blocks the installation input 3 step voltage (at the same time, the voltage Ug takes a zero value), prohibits the switching of the prohibition element 5 into the entry state of the formation-14, and zeroes the bits of the counter 6 in order to provide a new measurement cycle. The first one after the strobe pulse and, the signal U, starts the gate pulse generator 14, giving rise to the next measurement cycle Ui, during which the processes are repeated.

Claims (1)

Formula A device for measuring the nonlinearity of a sawtooth voltage, containing, its differentiating stage, whose input is measuring the input of the device, a pulse generator of adjustable duration, the input of which is the clock input of the device, sequentially connected step voltage generator 7 a comparator, a prohibition element, a pulse counter and a display unit, as well as an amplitude detector, a nonlinearity sign detector and a pulse tip selection unit connected by one input to the reference input of a step voltage generator, and an output to the second input of the comparator and through a nonlinearity sign detector to the block indication, while the control input of the step voltage generator is connected to the synchronization input of the device, and the second input of the prohibition element is connected to the output of the pulse generator of adjustable duration, from ichayuschees in that, with a view to extending the dynamic range of the measured voltages introduced dividing unit, two switches, a source of reference voltage and the strobe pulse generator, the input unit dividing the dividend in a Con pfloDLl G LLLALLALL LJ -. .,. П-Г1 Editor N. Yatsola Compiled by N. Mikhalev Tehred L. Oleinik Order 2126/43 Circulation 728 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 508 To the output of the differentiating cascade, the divider input is connected to the output of the first switch, the first input of which and the scale input of the dividing unit are connected to the voltage source and the reference input of the step voltage generator, the output of the dividing unit, which is connected to the second input of the pulse top selection unit, and the other output of the second switch is connected to the second input of the first switch through the amplitude detector, the input of the strobe pulse generator is li ne entry to the synchronization device, and the output strobe pulse shaper is connected with the control inputs of switches ustano- -Generator eternal input step voltage, a third input of the prohibition and the adjusting input of the counter. .,. П-Г1 Lf Proofreader G. Reshetnik