Exam Revision Flashcards
(22 cards)
What are 4 key characteristics to consider of a ADC when designing a signal processing circuit
Conversion time
Bandwidth
Resolution
Dynamic range
How much voltage does an LED use
2V
How does EMI cause noise to be generated at a receiving unit in a unbalanced interface
Introducing an EMI to unbalanced voltage/ current signal lines causes a potential difference in between the earth lines
What are the benefits of an industrial amplifier
Industrial amplifiers have buffers on the inputs, with very high input impedance on both signal lines, high CMRR and low DC offset
What are industrial amplifiers used for
They are used in high accuracy, differential input with controlled or fixed gain
What are some examples of industrial amplifiers uses
Heart rate monitors, ECGs, and EEGs
How can using a balanced interface reduce noise created by EMI
The EMI affects both lines equally, cancelling out its affects so there’s no voltage across the earth lines
What are the parts of a sample and hold circuit
Input buffer
FET
C
Output buffer
What does the input buffer do in a sample and hold circuit
Prevents loading of source
What does the capacitor do in a sample and hold circuit
Holds charge and voltage
What does the FET do in a sample and hold circuit
High-impedance switch, while on the capacitor is charged, when off the capacitor is holding charge
What does the output buffer in a sample and hold circuit do
Prevents the discharge of the capacitor due to high input impedance
What is open loop voltage gain in regards to an operational amplifier
The open-loop gain is a very large gain when no feedback is applied.
The output tends to infinity but is limited by the supply voltage
What are two methods of removing interference from heart-beat signal measurements
Cable shielding
Differential signal lines
What do buffers do on a circuit
Provide high input impedance
How does a flash ADC work
A flash ADC consists of a large number of comparators that compare the incoming voltage signals with pre-set reference voltage levels
What are the parts of a PLL circuit
Frequency generator
Phase detector
Low pass filter
Voltage controller oscillator
Frequency divider
High frequency output signal
What is an unbalanced mixer
Contains both input frequencies and their sum and differences
What is a single-balanced mixer
Contains sum and difference and only one of the input frequencies
What is a double-balanced mixer
Contains the sum and difference but not f1 or f2
What is a tank circuit
And circuit containing only a capacitor and an inductor
What does a tank circuit do
Stores and exchanges energy from the magnetic fields from the inductor and the electrical fields from the capacitor
