# GATE Questions & Answers of Data Converters: Sample and Hold Circuits, ADCs and DACs

## What is the Weightage of Data Converters: Sample and Hold Circuits, ADCs and DACs in GATE Exam?

Total 6 Questions have been asked from Data Converters: Sample and Hold Circuits, ADCs and DACs topic of Digital circuits subject in previous GATE papers. Average marks 1.83.

In an N bit flash ADC, the analog voltage is fed simultaneously to 2N−1 comparators. The output of the comparators is then encoded to a binary format using digital circuits. Assume that the analog voltage source Vin (whose output is being converted to digital format) has a source resistance of 75 Ω as shown in the circuit diagram below and the input capacitance of each comparator is 8 pF. The input must settle to an accuracy of 1/2 LSB even for a full scale input change for proper conversion. Assume that the time taken by the thermometer to binary encoder is negligible.
If the flash ADC has 8 bit resolution, which one of the following alternatives is closest to the maximum sampling rate ?

Consider a four bit D to A converter. The analog value corresponding to digital signals of values 0000 and 0001 are 0 V and 0.0625 V respectively. The analog value (in Volts) corresponding to the digital signal 1111 is ________.

In the following circuit, the comparator output is logic “I” if V1 > V2 and is logic “0” otherwise. The D/A conversion is done as per the relations

$V_{DAC}=\sum\limits_{n=0}^32^{n-1}b_n$ volts, where b3 (MSB), b2, b1 and b0 (LSB) are the counter outputs the counter starts from the clear state

The stable reading of the LED display is

In the following circuit, the comparator output is logic “I” if V1 > V2 and is logic “0” otherwise. The D/A conversion is done as per the relations

$V_{DAC}=\sum\limits_{n=0}^32^{n-1}b_n$ volts, where b3 (MSB), b2, b1 and b0 (LSB) are the counter outputs the counter starts from the clear state

The magnitude of the error between VDAC and Vin at steady state in volts is

In the Digital-to-Analog converter circuit shown in the figure below, VR = 10 V and R = 10 kΩ.

The current i is

In the Digital-to-Analog converter circuit shown in the figure below, VR = 10 V and R = 10 kΩ.

The voltage Vo is