Table of Contents

- 1 What is pedestal error?
- 2 What are ADC errors?
- 3 What is droop in sample and hold?
- 4 How is ADC value calculated?
- 5 What is hold Offset example?
- 6 What is droop rate?
- 7 How do you fix ADC error?
- 8 How do I find ADC error?
- 9 How are conversion errors minimised in an ADC?
- 10 What happens when code 10 is missing in ADC?

## What is pedestal error?

pedestal error (of an analog-to-digital converter or a digital-to-analog converter) (Ep) A dynamic offset error produced in the commutation process.

### What are ADC errors?

Analog-to-Digital Converter (ADC) absolute error (absolute accuracy) is the total uncompensated error and includes quantization error, offset error, gain error, and non-linearity. It is the amount of deviation from the ideal ADC transfer function without compensating for gain or offset errors.

#### What is droop in sample and hold?

Another measure is called droop rate in hold mode, which characterizes a slow change in output voltage in hold mode. When high-speed input signals are sampled, it causes the held voltage to be significantly different from the ideal held voltage.

**What is sampling mode and holding mode?**

In electronics, a sample and hold (also known as sample and follow) circuit is an analog device that samples (captures, takes) the voltage of a continuously varying analog signal and holds (locks, freezes) its value at a constant level for a specified minimum period of time.

**What causes ADC gain error?**

If the transfer function of the actual ADC results in ADC saturation before the input voltage reaches maximum, a positive gain error is produced. If the transfer function of the actual ADC is such that the ADC does not reach full-scale value when the input voltage is at maximum, a negative gain error is produced..

## How is ADC value calculated?

ADC has a resolution of one part in 4,096, where 212 = 4,096. Thus, a 12-bit ADC with a maximum input of 10 VDC can resolve the measurement into 10 VDC/4096 = 0.00244 VDC = 2.44 mV. Similarly, for the same 0 to 10 VDC range, a 16-bit ADC resolution is 10/216 = 10/65,536 = 0.153 mV.

### What is hold Offset example?

SAMPLE-TO-HOLD OFFSET: A step error occurring at the initiation of the Hold mode caused by “dumping” of charge into the storage capacitor via the capacitance between the control circuit and the capacitor side of the switch (e.g., the gate-to-drain capaci- tance of a field-effect transistor).

#### What is droop rate?

The droop rate is the downward slope of the top of the output voltage pulse resulting from a flat- top current input pulse. The lower trace represents the applied current pulse. The droop rate is the first term (linear) of the power series representing that exponential decay.

**What is the main function of DAC converter?**

A digital to analogue converter (DAC) converts a digital signal from the computer into an electrical voltage which can be used to drive electrical equipment, for example, a stirrer motor.

**What is the drawback in zero crossing detector?**

What is the drawback in zero crossing detectors? Explanation: Due to low frequency signal, the output voltage may not switch quickly from one saturation voltage to other. The presence of noise can fluctuate the output between two saturation voltages.

## How do you fix ADC error?

Two ways to adjust for gain error are to either tweak the reference voltage such that at a specific reference-voltage value the output gives full-scale or use a linear correction curve in software to change the slope of the ADC transfer-function curve (a first-order linear equation or a lookup table can be used).

### How do I find ADC error?

The gain and offset error will be calculated using the equation of a straight line y = mx + b, where m is the slope of the line and b is the offset. The gain error can be calculated as the slope of the actual ADC output divided by the slope of the ideal ADC output.

#### How are conversion errors minimised in an ADC?

UNDERSTANDING AND MINIMISING ADC CONVERSION ERRORS Sampling the signal at twice the analog signal frequency will not result in a loss of information. If sampling frequency is less, then the information will be lost. This is a standard theorem that applies to ADCs in general.

**What is the quantization error for an ADC?**

UNDERSTANDING AND MINIMISING ADC CONVERSION ERRORS The quantization error is the error introduced because of the process of quantization. Ideally any analog input voltage can be maximum of 1/2 LSB away from its nearest digital code. So the quantization error is 0.5LSB for the ADC.

**What does a DNL error on an ADC mean?**

The key for good performance for an ADC is the claim “no missing codes.” This means that, as the input voltage is swept over its range, all output code combinations will appear at the converter output. A DNL error of <±1LSB guarantees no missing codes (Figure 1a). In Figures 1b, 1c, and 1d, three DNL error values are shown.

## What happens when code 10 is missing in ADC?

When the input voltage is swept, Code 10 will be missing. When DNL-error values are offset (that is, -1LSB, +2LSB), the ADC transfer function is altered. Offset DNL values can still in theory have no missing codes. The key is having -1LSB as the low limit.