Analog Top Talks in April 2019 on EDABoard.com

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.

Opamp circuit simulation – Is the following open loop transient simulation of an opamp correct?

Current excitation for sensor – I have the below circuit which provides the 0.5mA constant current supply for sensor. I’m designing a precision measurement and would like to know, does the output of the sensor gets affected with C9 value? Read more

Creating a very sharp pulse generator – I want to generate a clock with about 4 MHz frequency (should be adjustable) which is very clean and sharp. I have tested a crystal collpits circuit but it is not sharp enough. Any suggestions? Read more

Shifting the waveform using opamp – I am trying to generate the SPWM using analog circuit, by comparing sine with a triangular wave the output will be sinusoidal PWM.
I am generating Sine wave of 50 HZ using Wein bridge oscillator.
The triangular wave is generated by a square wave generator and integrator.
Two waves are compared using comparator (LM393). Read more

SMPS electrical noise issue – I’m using a class 2 medical graded SMPS in our device. So an earth connection is not recommended. When connecting SMPS to load (contains Capacitive Touch LCD), the touch function is affected by SMPS noise. When connecting SMPS earth point to Protective Earth, LCD touch function working properly. Read more

Voltage spike problem – I have got voltage spikes in push-pull topology. I have used a snubber but it didn’t work. This is a gate-emitter voltage. As you can see it has something like noise. It seems this is my problem but I don’t know how to remove it. Read more

High power LED “function” controller – I am trying to build a “simple” discrete analog circuit to control a high power RGB LED (3x3W). The LED can be configured as either common cathode or common anode. The circuit needs to do the following: when power is applied, the LED should shine – colour is determined by 3 jumpers (RGB on/off). Read more

Design of voltage-controlled oscillator – I am trying to emulate IC566 in a simple project board for Audio frequency range. Which components would be better to use in the project? Read more

S-parameter results with “term” – This is a very basic concern which I don’t understand. I have an LPF circuit which has a term as input and output. I define the term with the default setup. I don’t understand how I am getting LPF output s21 if nothing has given. Is the port acting as an input source with some power? Read more

Layout PCB RF amplifier – If I design the layout PCB like this picture and if the transistor input that I rounded was sharpened like in the picture, what would affect the matching impedance? Read more