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MOSFET getting very hot – In this schematic, the VCC feed with a less than 1 A MOSFET gets hot in seconds and it won’t stop. At this stage, I see voltage drop so the gate voltage will be something like 3- 4 V and it seems that the MOSFET is not ON completely. If I feed with high current, then I see it will take a full load for a few milliseconds and then will go back to normal. Read more
Shunt current monitor in DIP package -I need to design a short-circuit protection using a high-side shunt (200A/60mV). I’ve checked the TI/Linear/Avago/AD websites but I didn’t find any current shunt monitor in DIP(8) package. I do prefer a dedicated high-side monitor but any low-side one could be adapted. Does anyone have any evidence of such an IC? Read more
How to loopback MIC and earpiece? -I have a design which has a 16 ohms earpiece output, and a several kilo-ohms MIC input. Now I want to loopback the MIC and earpiece so that I can test the audio quality by CMU200, etc. The question is how to loopback MIC and earpiece? Directly linking MIC+ to EAR+ and MIC- to EAR- seems not to impedance match? Read more
Difference between frequency and frequency function? – I’m trying to find the period of a waveform in Cadence Virtuoso ADE using the calculator function. I see in the user manual that there are two things (please see below picture): (1) Freq function (2) Frequency Function. Read more
I-V characterizer schematic – How do I develop hardware for characterizing two-port devices? It needs to be accurate enough and work at high speed — more than 10Msamples/s. Please review my schematic. Read more
Help for differential amplifiers – I am developing a differential amplifier for my PFC Applications. Here I am attaching the same. Let me know the where the VP and VN will connect to the shunt and Why? I am getting confused while designing a differential amplifier. Can I simply use the Inverting amplifier and proceed ahead. Read more
Phase noise increases with reduction in oscillation frequency – I fabricated an IC that has a quadrature VCO and I am measuring the phase noise. I observed in simulations that when I change the varactor voltage to change the frequency, the phase noise reduces (i.e. phase noise performance improves) as I reduced the oscillation frequency. Why does this generally happen? Read more
Audio signal coupling capacitor – While searching on the internet for 10 W audio amplifier, I found a circuit using the 4 transistors shown below. My questions:
1. Is the value of coupling capacitor (c1) appropriate for working with an audio input signal?
2. If the value is enough to couple, then how do I calculate the value of the capacitor (c1)?
Note: According to my calculation the range of capacitor could be of few microfarad, but according to the given value in circuit diagram, it only passes signal above few kHz frequency. Read more
The ground termination between the comparator and the load – I have a problem measuring the current load by the comparator. Below is the block diagram for our product. We have a Q1 to control the battery ON/OFF by an MCU. When the MCU is cut off from the Q1, the Load is not cut because the path is changed; current flows through the op amp TLV8802 input to ground when I cut the supply of TLV8802. Since we are operating a very high-current motor, change to the P-FET to cut the power is not available (higher Rds). Any ideas? Read more
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