Analog and electronic circuits

What increases the thermal noise (Johnson noise) voltage generated in a resistor?

  1. AHigher resistance, higher temperature and wider bandwidth
  2. BLower resistance
  3. CLower temperature
Show answer and explanation

Answer: A. Higher resistance, higher temperature and wider bandwidth

The thermal noise voltage is √(4kTRB) (k: Boltzmann constant, T: absolute temperature, R: resistance, B: bandwidth). It grows with resistance, temperature and bandwidth. Circuits handling tiny signals keep resistance and bandwidth to the minimum needed to reduce noise.

Practice this topic Back to topic

More Analog and electronic circuits questions

  1. Which circuit adds two voltages with opposite temperature coefficients to create a reference voltage of about 1.2 V that hardly depends on temperature?
  2. Which circuit generates a clock at a frequency such as an integer multiple of a reference clock while locking its phase to the reference?
  3. What is the circuit called in which the input resistor of an op-amp inverting amplifier is replaced by a capacitor?
  4. Which circuit has different thresholds for rising and falling inputs and prevents the output from chattering due to noise?
  5. Which metric indicates how well a circuit keeps supply-voltage fluctuations from reaching its output?