Top analog threads on EDAboard.com – September

High-side switching using P channel – I am using LTC4412 for power path switching. In the example, it shows use of P Channel with drain connected to Positive and Source to load. I understand that this would avoid reverse flow but shouldn’t the voltage input be connected to Source of MOSFET?  Read more
I am trying the following circuit:

Common source – can zero come before unity crossover? – I am struggling with the transistor models of a new process. I get all kinds of weird stuff. Specifically, can the zero of an ordinary diff pair (i.e., Common Source stage) come before the unity crossover? Read more

Would like some ideas for a 100W RMS power supply – I am rediscovering this fascinating world of electronics and DIY things recently and decided to do something with my spare time. I decided to adapt some old car speakers and an amplifier into my new PC sound.So my problem here right now is how will I make a good PSU for this little guy? I’ve heard I can’t use a SMPS (switched mode power supply) for sound applications or there will be some noise on the signal.The problem is that creating a 100W linear power supply will cost an absurd price with a 127V/12V at 10A transformer! The transformer will cost R$105,75 to be exact and will weight almost 3 kg. Read more

What’s wrong with my op amp? -I built a simple op amp circuit using AD8226ARMZ and AD8669ARUZ. My signal is several Hz, and VREF is 1.2V. After diff  op amp AD8226, I used a 10uF(C7) to isolate DC, I hope pin5 of AD8669 is just small AC signal (about several Hz), but the tested value of pin5 is about 0.6V, and the op amp output pin7 is about 3.3V, the up rail of op amp. The original design is that C7 at the position of the output of U1B, but that will cause waveform distortion. So I changed 10uF from output of U1B to input of U1B. What’s wrong with it? I designed U1B with AC 750 times amplifies,but obvious DC is very high. Read more

ADC monte carlo simulation – I did monte carlo simulation of my 3-bit flash ADC. Any suggestion on how can I explain the simulation in the text? Which factors should I focus on while writing a paragraph about the monte carlo simulation result? Read more

Output single supply input limitation – Is there any way to use a single-supply op amp (rail-to-rail) to amplify a 10-100mv signal? Or for such a small range we have to use dual supply. Read more

Prevent audio leaking – I’m working for a design which light LED when its detect audio input to the circuit from a mobile phone. There are few same design doing the same thing. Detect audio and light LED is fine but the problem is Audiosensor circuit leaking audio to power source. I have check with Audiotracer. I need help to prevent audio leakage to power source.  Read more

Measuring current without using shunt resistance – Can someone guide me on making a measurement current in the following circuit using HEXFET instead of shunt resistance? Read more

Adaptation of a 50 Ohm port to a CMOS ring oscillator – We are getting a linear output for the CS-VCO from 1GHz to 5GHz. This is when we attached M_Probe (Measurement Probe) to view the output voltage with respect to time. But, attaching a 50 Ohm port collapses the output because of the impedance mismatch. From what we have seen, a 50 Ohm port pulls current (in mA) into it. To nullify this current, we had to increase the port impedance to as high as 100 Mega Ohm to 1 Giga Ohm. We need a 50 Ohm port to check for oscillator noise, tuning range, output power spectrum etc. As 1 GOhm is impractical for real life scenario, what are we doing wrong? Or are the parameters to be blamed for? Or, is any matching circuit needed here?

Resistive feedback op am with tiny loop gain – I always learned the loop gain should be as high as possible for good accuracy, linearity etc. Does it make sense to use an amplifier like this where the loop gain is even negative? (one advantage is that it is unconditionally stable). Read more