Analog Top Talks in April on EDABoard.com forums

Peer-to-peer, engineer-to-engineer questions and answers from the EDABoard.com engineering community around analog ICs and analog design. Click the “Read more” link and follow the entire conversation and maybe add your two cents by logging in to EDAboard.com.

Bode plot DC gain not showing in boost converter transfer function – I have designed a boost converter with peak current mode control and I wanted to evaluate the transfer function in bode plot of the Verr to Vout as you can see in the files adding the boost converter gives a bode plot without a DC gain. I would love to know what I have missed getting the DC gain as the shape of the bode plot is good. Read more

Damping factor of amplifier in LTSpice simulation – I’ve to measure the damping factor of my amplifier using LTspice simulation. I’ve actually connected a voltage source to the output in with an 800Ω series resistor and grounded the amplifier input. The DC transfer function shows me this result:

It’s correct what I’ve done? How to calculate now the damping factor? Read more

Bypass battery for micro USB direct power –  I am modifying it to make a prop for an amateur film. I tore one apart and was wondering if I could bypass the battery and have it work just while being plugged in. Not sure how the wiring would be set up. The second question is about the black box with copper wire rolled up in it. I am wondering if this can be removed/altered in size someway to fit my application. Read more

TPS54331 oversupply output no load voltage –  I am using the TPS54331 regulator. The input is 4.5V to 6V and I  require a 3.3v constant to vary the input voltage 4.5v to 6V or 6V but in no load. Read more

Inverting low pass filter design – I want to design a low pass filter but I have some questions.  I simulated it in PSpice but there is a capacitor named here Ci. I try to remove it and the circuit gives the same result. Another technical question — why we don’t use inductors in filters? Read more

Capacitor switchover, simple implementation – I want to implement the following circuit in the simplest way possible. The simple idea is to switch over C1 and C2 so that R3 does not (directly) draw current from V2. But I’m having trouble selecting the right components, especially as I believe FET’s are out the window due to their body diode. Read more

Ancient slow scan television, narrowband – Can you suggest how can this be done? Analog SSTV, NO computers, no high speed, nothing digital. Same way it was done in the sixties. Any sample circuits for the modulator and the demodulator sections? What considerations are missing? A modern surveillance camera does not scan slowly. Read more

Capacitor 30kVAR 100Arms – I read the text, “Four of 30 kVAR 100Arms 0.47uF capacitor with the total capacitance of 1.88uF.” I do not know what kind of capacitor operates at 30 kVAR 100Arms?
30 kilovolt-ampere reactive
100 Amper Root Mean Square
I do not know what kind of capacitor to look for. Read more

Fully differential amplifier MISMATCH analysis – I am designing a two-stage fully differential amplifier. Both stages are CMFB compensated. My problem is that after the first stage there is so much offset in the output of the first stage (because of mismatch). Second stage outputs are going to Vdd and ground. Is there any solution to it? Read more

Need help with transformer hookup – I’m a bit confused as to how to hookup the primary to the wall in order to obtain the 385V from the transformer’s secondaryI’mIm also unsure how much current the 385V will provide. Read more