Comparator

Question 1

The amplifier, filter, and oscillator applications illustrate a fair sampling of typical ________ uses.

Answer 1

OP-AMP

Question 2

compares one analog voltage level with another analog voltage level, or some preset reference voltage, VREF and produces an output signal based on this voltage comparison.

Answer 2

OP-AMP Comparator

Question 3

In other words, the op-amp voltage comparator compares the ________ of two voltage inputs and determines which is the ________ of the two.

Answer 3

magnitudes, largest

Question 4

Comparator Characteristics

Real comparator circuits do not display an ____________ in the output.

Answer 4

abrupt transition

Question 5

Comparator Characteristics

is extremely high in the transition region.

Answer 5

Voltage gain

Question 6

Comparator Characteristics

Internal circuitry of the an integrated comparator is similar to that of an OpAmp. One important difference is that ________________________ is not needed for comparator because it is not operated in __________ feedback.

Answer 6

frequency compensation, negative

Question 7

Comparator Characteristics

So, roughly, OpAmp can be used as a comparator circuit, but not vice versa due to __________________.

Answer 7

frequency compensation

Question 8

Comparator Characteristics

Comparator is usually designed to have small ________________ and small ________________ for output signal in response to inputs.

Answer 8

transition region, propagation delay

Question 9

Comparator Characteristics

Comparator also suffer from non-idealities, such as: (3)

Answer 9

1. bias current
2. offset current
3. offset voltage

Question 10

Comparator Characteristics

Comparators are often used as the ________ between analog and digital circuits, since it converts analog signal into __________.

Answer 10

interface, logic levels

Question 11

Comparator Characteristics

Power supply for ________ signal in many systems are 10 to 15V. But power supply for ________ signal is 1.8 to 5V.

Answer 11

analog, digital

Question 12

Comparator Characteristics

Suppose for digital signal, 0V stands for logic 0 and 5V for logic 1, then a comparator needs to produce an output of 0V and 5V with input and internal signal at 0 to 15V. An____________ are very useful in the case.

Answer 12

open-collector output stage

Question 13

Output Type of Comparator: (2)

Answer 13

1. Open-drain/open-collector output (most common)
2. Push-pull drain-drain/collector-collector output

Question 14

• Useful for wired-or output applications
• not present in TLV1701 +Vs and Vpull-up may be at any
  level between +2.2 to +36 V

Answer 14

Open-drain/open-collector output

Question 15

Comparator Inputs

An ________ comparator compares two ____________ and produces a logic ________ whose value (high or low) depends on which of the two input is ________. The circuit symbol for a comparator is identical to the one for OpAmp.

Answer 15

ideal, input voltages, output signal, larger

Question 16

Comparator Inputs

If Vi is positive, the output is ________. If Vi is negative, the output is ____.

Answer 16

high, low

Question 17

Comparator Inputs

The ____________ may be symmetrical or asymmetrical, depending on the needs of the digital circuits that follows the comparator.

Answer 17

output logic levels

Question 18

Basic Comparator (cont.)

As comparator’s output voltage changes and varies between ________, it can be said that it is a type of _________ to _________.

Answer 18

+-Vsat, Analog to Digital converter

Question 19

Basic Comparator (cont.)

Sometimes, due to ________ input voltage Vin, OP-AMP may ________.
* To prevent it, we use two ________. Because of these diodes D1, and D2, the ________________ Vid of the OP-AMP is ____________ to either +0.7V or -0.7V; hence they are called ____________.

Answer 19

excessive, damage, diodes, diffrential input voltage, clamped, Clamp Diodes

Question 20

An immediate application of the comparator is the ____________________________________________.

We can use both, inverting and non-inverting comparators for Zero-Crossing Detector. The difference will come in the output waveform.

Answer 20

Zero-Crossing Detector or Sine wave to Square wave converter

Question 21

• A slowly changing input signal (low-frequency) makes Vin take longer to cross 0V, causing Vo to switch slowly between saturation levels.
• ________ at the op-amp input can make Vo fluctuate, creating false zero-crossings.
• These issues are solved by using ____________, which speeds up the output transition and reduces false triggering from noise.

Answer 21

Noise, positive (regenerative) feedback

Question 22

Positive Voltage Comparator -Non-inverting Comparator Circuit

detects when the input signal, Vin is ABOVE or more positive than the reference voltage, Vref producing an output at Vout which is HIGH as shown.

Answer 22

Positive Voltage Comparator / Non-inverting Comparator Circuit

Question 23

Negative Voltage Comparator - Inverting Comparator Circuit

detects when the input signal, VIN is BELOW or more negative than the reference voltage, VREF producing an output at VOUT which is HIGH as shown.

Answer 23

Negative Voltage Comparator / Inverting Comparator Circuit

Question 24

is basically the inverting and the non-inverting comparators above combined into a single comparator stage.

Answer 24

Window Comparator

Question 25

The **window comparator** detects ____________ levels that are **within a specific band** or **window of voltages**, instead of *indicating* whether a **voltage** is ________ or ________ than some **preset** or **fixed** **voltage reference point.**

Answer 25

input voltage, greater or less

Question 26

# Comparator Voltage Level Detector ________________ provides a **set of reference voltages** for the ________ **op-amp comparator** circuits. To produce the **four** ____________ will require **five** _________.

Answer 26

voltage divider network, individual, reference voltages, resistors

Question 27

# Effect of Input Noise in Comparator *In some applications, there is **undesired variation** in **voltage value** is occurs at the **input** side. The ________________ interlinked with the ________. It shows the **sine waveform.** (superimposed noise)

Answer 27

noise or undesired voltage variation, input voltage

Question 28

# Reduction of Noise Effects through Hysteresis *Due to **noise signal** at ____________ is **created** since ____________ **changes state** from **negative output** *to the* **positive output** state at **similar** ____________ value which changes the condition in the **reverse state** from **positive** *to* **negative**.

Answer 28

input faulty output, comparator, input voltage

Question 29

# Reduction of Noise Effects through Hysteresis When the **value** of **input voltage** is about the ________________________ **exists** and **less noise variation** causes the *comparator* to **change its state** from _______ to _______.

Answer 29

reference voltage unstable state, first to second.

Question 30

# Reduction of Noise Effects through Hysteresis To **decrease** the **response** of comparator **towards the noise** the method incorporating ____________ which known as ________ is used.

Answer 30

positive feedback, hysteresis

Question 31

indicates that the **large value reference** when the **input voltage moves** from **less to high** value than it moves from **high to low** value.

Answer 31

Hysteresis

Question 32

# Reduction of Noise Effects through Hysteresis The **2 reference points** are denoted as **UTP** or ________________ and **LTP** or ________________. This 2 hysteresis is **created** with the use of ______________ **configuration**.

Answer 32

upper trigger point, lower trigger point, positive feedback

Question 33

**Inverting** comparator with **positive feedback** is known as the _____________________

Answer 33

Schmitt Trigger or Squaring Circuit.

Question 34

____________ ? It *converts* **irregular-shaped waveforms** to a _______________.

Answer 34

Schmitt Trigger or Squaring Circuit, square wave pulse

Question 35

# Schmitt Trigger or Squaring Circuit. The **input voltage** Vin ________ (changes the state of) the **output** Vo *every time* it **exceeds** certain ____________ called the ________ **threshold voltage** Vut and ________ **threshold voltage** Vlt

Answer 35

triggers, voltage levels, upper, lower

Question 36

1) These **threshold voltages** are **obtained** by *using* the ____________ **R1 - R2**, where the ________ **across R1**, is **fed back** to the __________ **input**. 2) The **voltage across R1** is a ____________ **threshold voltage** that **depends** on the ________ and ________ of the **output voltage Vo**. 3) When **Vo = +Vsat**, the **voltage across R1** is called the ____________________, Vut. 4) The ________ must be **slightly more** ________ than **Vut** in order to cause the **output Vo**, to ________ from **+ Vsat to - Vsat**

Answer 36

1. voltage divider, voltage, non-inverting 2. variable reference, value, polarity 3. upper threshold voltage 4. input voltage, positive, switch

Question 37

The primary function of the **Schmitt Trigger,** is to **convert** ____________ **waves**, ________ **waves** or ____________ **inputs** into ____________ **waves**.

Answer 37

noisy square, sine, slow edges, clean square

Question 38

# Schmitt trigger's applications **Schmitt triggers** are typically used in ____________ **configurations** for ____________ and ____________ **configurations** to *implement* _____________.

Answer 38

open loop, noise immunity, closed loop, function generators

Question 39

# Schmitt trigger's applications * **Analog to digital conversion:** The **Schmitt trigger** is **effectively** a ________ **analog to digital converter**. When the **signal reaches a given level** it **switches** from its _____ to _____ **state**. * Level detection. * Line reception.

Answer 39

one bit, low to high