SU805418A1 - Device for testing aperture time of analogue storage units - Google Patents

Description

one

The invention relates to a measurement technique and can be used to determine the aperture time of analogue memory of 5 & amps (devices), usually included in analog-to-digital converters (ADC) for emitting signals with a wide spectrum. Aperturna

The inaccuracy arises due to the uncertainty of the dating (time reference) of the memorized instantaneous. continuous input values

a signal that converts the ADC itself to a digital code. The uncertainty of the position of the measured instantaneous values in time is manifested as a result of subsequent processing or restoration of the signal. As a hindrance (error). . A device is known that normalizes to the magnitude of this error, since it depends on the nature of the input signal, and the uncertainty of the time position of the reference is the aperture time l. At the same time, the aperture time does not include the constant in magnitude of the delay of the transition of the CCD to the storage mode after applying the corresponding signal to its control input, since it is always

accounted for. The aperture time is actually a change in the specified delay depending on the rate of change of the input signal.

and its level.

The closest in technical essence to the present invention is a device in which the estimation of the parameters of the CCD is carried out using an oscillographic method. A differential input oscilloscope (or a dual-beam oscilloscope) is connected to the input and output of the CCD and signals are observed that have characteristic features associated with the CCD transition from the sampling (tracking) mode to the 2 J. storage mode.

However, the oscillographic method is inaccurate and allows, at best

case, get a qualitative assessment of the parameters of the ABC.

The purpose of the invention is to improve the accuracy of the device.

The goal is achieved

the fact that in the device for controlling the aperture time of the blocks of the extrashort memory containing the ADC, the first input of which is connected to the input of the device, the pulse shaper)

sampling and storage, the output of which

connected to control output. devices, synchronizer and bus

a zero potential, a adjustable delay element, an adjustable DC voltage source, a sinusoidal voltage source and a key, the output of which is connected to the analog output of the device, are introduced; 1 key inputs are connected to the outputs of the sinusoidal voltage source, the input of which is connected to the synchronizer output and the adjustable input the delay element, the output of the adjustable delay element is connected to the input of the sampling and storage pulse generator, the second input of the analog-digital converter is connected to one m from the inputs of a sinusoidal voltage source and an adjustable constant voltage source, the other input of which is connected to the zero potential bus.

Figure 1 shows the functional diagram of the device in figure 2 - time diagram.

The circuit contains ADC 1, a driver. 2 pulses of sampling and storage, adjustable delay element 3, synchronizer 4, sinusoidal voltage source 5, adjustable voltage constant source 6, key 7, device control output 8, device analog output 9, device 10 input and zero potential bus 11 and an analog memory block 12.

The device works as follows.

When determining the aperture time, the main input of the analog storage unit 12 (device output 9) is first supplied with a constant voltage UG / and the control input (device output 8) —sampling and storage pulses. Measuring the difference between the DC voltage at the input and the voltage at the output of the analog memory block 12 - in the storage mode using the ADC1, the magnitude of the LUo displacement, usually occurring during the transition to storage, is found due to the passage of the control pulse through the parasitic capacitances of the block 12 analog., memory. Then, a signal is supplied to the input of the analog memory 12, which represents the sum of a constant and a variable voltage; |

and u, s.,

S Q p wherein the sinusoidal signal must be synchronized with the sampling and storage pulses. The frequency of the latter must be either 2 times the frequency of the sinusoidal signal, or less, at a ratio expressed by a fractional number. It is necessary that the start of storage should be positively positive. and a negative half wave of a sinusoidal signal. By adjusting the relative position of the sinusoidal signal and the sampling and storage pulses, the ADC1 readings are equal on the positive and negative half-waves of the sinusoidal signal (l). aperture error component associated with the sign and rate of change of the input signal

u ;,

Next, a constant voltage source 6 is adjusted :: taking into account the allowable limits of the input signal, and, Uyy, -, the maximum difference between the readings of ADC1 on the negative and positive half-waves of the sinusoidal signal is found. This difference is the component: UQI aperture error, occurs as a result of the influence of the input voltage level on the delay of unlocking the key of the block 12 analogue two

- memory. The amplitude of the sinusoidal signal is a smaller part of the maximum allowable change in the signal (and, ah - "Jtviiv)" at the input of block 12 of the analog memory. The sum of the components of D io and l (Jg are

0 full aperture block error, analog memory:

.. a Since the rate of change of the sine wave at the error points is known

AU TT-J

translate the value of the aperture error in aperture time in accordance with the formula.

4- - a- hell Un,

5 The use of the proposed device allows to significantly improve the accuracy of determining the aperture time, since the aperture error associated with the latter

0 is measured by a differential method, the effect of instability of the sources of test signals is insignificant. In addition, the use of ADC allows you to automate

f the whole measurement procedure, including

automatically adjusting the pulse holding rate of the samples and storing and calculating the aperture time.

Claims (2)

1. Kaspirovich, A.N., et al. On the expediency of using a push-pull sampling and storage device. Mr. Avtometri, 1973, 3., 2.Solonenko V.I. A high-speed microelectronic ADC (prototype). - Workshop Workshop Analog-to-Digital Converters, Novosibirsk, 1971. tjai qi (wound 1za9 BblffopKO Storage BuiSopKO