SU919075A1 - Device for checking digital-analogue converters - Google Patents

Description

I

The invention relates to an analog-digital technique and can be used to control the linearity of digital-to-analog converters (D / A converters) both in production and in service.

A device for measuring the error of a digital-to-analog converter is known, comprising a pulse generator, a first binary estimator measured by a D / A converter, a second binary estimator, a reference PAP, a code comparison unit, a subtraction and gain element, an analogue: a memory device and an indicator 1.

The drawback of the device is the limited accuracy and complexity of the functional scheme of applying the reference DAC.

It is also known a device for monitoring digital-to-analog converters, comprising a counting pulse generator, a binary counter, a DAC whose inputs are connected to you;

meter strokes, a sawtooth generator, an indicator and a comparison unit, the first input of which is connected to the output of the DAC, the second input of the comparison unit is connected to the output of the saw voltage generator 2.

However, the device has limited accuracy in controlling the linearity of the DAC. due to the inaccuracy of the combination of the characteristics of the DAC and the sawtooth voltage generator, both during the initial installation and because of their temporal and temperature drift.

The purpose of the invention is to improve the accuracy of control of linearity of the DAC.

Claims (2)

The goal is achieved by the fact that, in a DAC control device containing a counting pulse generator, a binary counter, a DAC whose inputs are connected to the counter outputs, a sawtooth generator, an indicator and a scraper unit, the first input of which is connected to the DAC output, the second input of the block the comparison is connected to the output of the sawtooth generator, the output of the sawtooth generator is connected to the first input of the indicator, the second input of which is connected to the output of the higher bit of the binary counter, the output of the generator The counting pulse pulse is connected to the third input of the block, the output of which is connected to the output of the binary counter. In addition, the comparator unit contains two comparators, a constant-voltage source and an AND source, the first input of the comparator unit is connected to the non-inverting input of the first comparator and the positive pole of the constant-voltage source, the negative pole of which is connected to the inverter input of the second comparator, the inverting input of the first and non-inverting input of the second comparator are connected to the second input of the comparator unit, the outputs to the parators are connected to the first inputs of the And element, the third input of which is connected to the third stroke comparing unit, whose output is connected to the output of AND, Figure 1 is a functional diagram of the device for controlling the DAC; in fig. -2 - temporary diagrams of device operation. The device for monitoring the D / A converter contains a D / A converter 1 ,. binary counter 2, unit 3 of comparison, generator of k counting pulses, generator 5 of sawtooth voltage, indicator 6, Unit 3 of comparison consists of source 7 of constant voltage, first comparator 8, second comparator 9, and element 10. The output voltage | - generator of 4 counting pulses is a sequence of pulses with a high duty cycle. As indicator 6, either a frequency meter operating in the mode of measuring the ratio of the frequencies of two signals, or another similar device capable of monitoring amb hour the ratio of the two signals. The device works as follows. A DAC 1 converts the digital output of a binary counter into an analog signal fed to the first input of comparator 3, the second input of which receives a signal 11 (Fig 2) from the output of the sawtooth voltage generator 5, and the possible voltage values of the output signal 12 The DAC 1 (taking into account their allowable changes) is in the range from the minimum to maximum values of the signal voltage levels 11. At the time when the signal voltage 11 is in the range from (U) - E) to Uj, where the signal voltage 12, appropriate its current state of the binary counter 2, E is the voltage between the outputs of the constant voltage source 7, the comparison unit 3, when a pulse signal from the generator of counting pulses arrives at its control input, generates a coincidence signal at its output. The output signal of the comparison unit 3 is fed to the input of the binary-fo counter 2 and adds one to its state, the DAC 1 converts the new output signal of the binary counter 2 into an analog signal with voltage U. And when the voltage of the signal 11 changing di ff -r with a speed τt, a period of pulse pulses at the output of the generator of counting pulses) will be in the range from (E) to, at the output of the comparison unit 3, the next match signal is shown. When a binary counter 2 is switched, the DAC 1 generates a sawtooth step signal 12 at its output with a period equal to the signal period 11. The equality of the trigger switching period 13 of the high bit of binary counter 2 and the signal period 11 is recorded by indicator 6. If at least one of the output signal levels DAC 1 will be formed with an error exceeding the value (), where YPR is the smallest transformation step, then on the DAC 1 conversion characteristic there will be a violation of the monotony of the form) or C, 5: it; fcoiu after forming a DAC 1, for example, signal 14, binary counter 2 will not switch over the period, signal 11. Period 15 of switching the trigger of the higher bit of the binary counter will then be greater than the period of signal 11. The difference in the ratio of period 15 and period of signal 11 from units are registered by indicator 6, which in this case forms a signal about the occurrence of disturbances in the operation of the D / A converter. control of the inaccuracy of combining the characteristics of the DAC 1 and sawtooth generator 5. Claim 1. Inventory device for controlling digital-to-analog converters containing a counting pulse generator, a binary counter, a digital-analog converter whose inputs are connected to the outputs of a counter, a saw-voltage generator, the indicator and the comparison unit, the first input of which is connected to the output of the digital-analogue converter, the second input of the comparison unit is connected to the output of the sawtooth generator apg otlichayuschees p. In order to increase the accuracy of control of the digital-to-analog converter, the output of the saw-tooth voltage generator is connected to the first input of the indicator, the second one. the input of which is connected to the output of the higher bit of the binary counter, the output of the generator of counting pulses is connected to the third input of the comparison unit, the output of which is connected to the input of the binary counter. 2. The device according to claim 1, wherein the comparison unit is made on two comparators, a constant voltage source and an element, and the first input of the comparison unit is connected to the non-inverting input of the first comparator and the positive pole of the constant source the voltage, the negative pole of which is connected to the inverting input of the second comparator, the inverting input of the first and the non-inverting input of the second comparators are connected to the second input of the comparator unit, the outputs of the comparators are connected to the first two inputs of the element I, the third input of which is connected to the third input of the comparison unit, the output of which is connected to the output of the element I. Sources of information taken into account during the examination 1. USSR author's certificate No. 600719, Cl, H 03 K 13/02, 01.07. 7 2. USSR author's certificate in application N 280 093 / l8r2t, cl. H 03 K 13/03, 07.23.79 (prototype). i. I /