17 Matching Annotations
1. May 2022
2. ece.osu.edu ece.osu.edu
1. Robert Fenton, Electrical and Computer Engineering Professor Emeritus, pioneered the technology for the first wave of self-driving cars.

I had Fenton for a class once and during a lecture he asked a question of the class. A student raised his hand and answered. Professor Fenton listened and asked the class "Does anyone else agree that his answer is correct?"

About 85% of the students in the large lecture hall raised their hands.

He paused, shook his head, and said "Well, then I'm afraid you're all going to fail." Then he turned around and went back to writing on the chalkboard.

#### URL

3. Aug 2019
4. www.maximintegrated.com www.maximintegrated.com
1. the standard AES17 dynamic range measurement

AES17 doesn't define "dynamic range". It defines "Signal-to-noise ratio or noise in the presence of signal" which is what includes the test tone:

The test signal for the measurement shall be a 997-Hz sine wave producing – 60 dB FS at the output of the EUT.

#### URL

5. Oct 2018
6. www.shure.com www.shure.com
1. If the SM58 noise floor is calculated at room temperature, the voltage output is 0.00000032 volts.

This is equal to -130 dBV. The SM58 Vocal Microphone Specification Sheet says:

Sensitivity (at 1,000 Hz Open Circuit Voltage) –54.5 dBV/Pa (1.85 mV)

At this sensitivity, the self-noise would be 94 - (-54.5 - -130) = 19 dB SPL, which is pretty typical and certainly not "lower than can be typically measured".

#### URL

7. May 2018
8. www.radio-electronics.com www.radio-electronics.com
1. plus the impedance of the path from the inverting input to ground i.e. R1 in parallel with R2.

This is incorrect. If R1 is infinite and R2 is 0, the parallel impedance is 0 ohms, but the input impedance is much higher than the input impedance of the op-amp itself, due to feedback making the inputs very similar in voltage.

The input impedance is actually

$$(1 + A_0 B)\cdot Z_\mathrm{ino}$$

where

• $$A_0$$ is the gain without feedback (the open loop gain)
• $$B$$ is the fraction of the output which feeds back as a negative voltage at the input
• $$Z_\mathrm{ino}$$ is input impedance without negative feedback

For the above buffer example, it would be close to $$A_0 Z_\mathrm{ino}$$

Simpson - Introductory electronics for scientists and engineers section 7.2 Negative Voltage Feedback explains this clearly

#### URL

9. Apr 2018
10. web.mit.edu web.mit.edu
1. 10–27

Equation 10-27 is wrong:

• Resistors are in parallel, their noise does not sum.
2. Adding this and the 100-kΩ resistornoise to the amplifier noise

This is 3 terms (10 MΩ noise, 100 kΩ noise, and amplifier noise), but the equation only includes 2.

3. 10–25

Equation 10-25 has several errors:

• The left and right side are not equal.
• Resistors are in parallel, so their noise does not sum.
• Resistor noise needs to be multiplied by gain to be combined with 113.1 μV output noise of op-amp.
4. 10–23)

Equation 10-23 is incorrect:

• The noise of the resistors does not sum, since the resistors are in parallel and load each other. It would be equal to a single 50 kΩ resistor producing 4.0 μV.
• The 113.1 value is output noise. The resistor noise needs to be multiplied by the gain to get the output noise, too.
5. 0.1 F

Should be 0.1 μF

6. 0.1 F

Should be 0.1 μF

7. The noise calculations have many errors. See annotations on https://via.hypothes.is/http://web.mit.edu/6.101/www/reference/op_amps_everyone.pdf for details

8. which is 100

actually should be multiplied by the non-inverting noise gain, which is 101

9. TLE2201

Should be TLC2201

#### URL

11. intranet.ee.ic.ac.uk intranet.ee.ic.ac.uk
1. The noise calculations have many errors. See annotations on https://via.hypothes.is/http://web.mit.edu/6.101/www/reference/op_amps_everyone.pdf for details

#### URL

12. Mar 2018
13. www.analog.com www.analog.com
1. The poles of the Bessel filter can be determined by locating all of the poles on a circle and separating their imaginary parts byn2where nis the number of poles.

This is incorrect:

• The poles are not located on a circle
• The imaginary parts of the poles are not equally spaced

To generate the poles of a Bessel filter you need to use root-finding methods on the reverse Bessel polynomials. There's no other shortcut that I'm aware of.

2. The step response shows no overshoot

This is incorrect: There is a small amount of overshoot in Bessel filters.

#### URL

14. www.radio-electronics.com www.radio-electronics.com
1. with no overshoot

This isn't quite correct: Bessel filters have a small amount of overshoot.