Activity for jm567
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Question | — |
Measuring Input/Output Impedance with a VNA On paper you can measure the input impedance of an amplifier circuit by attaching a voltage source to the input, shorting the output, and calculating the resulting impedance from the voltage and current, or vice versa to find output impedance. But how would I measure ... (more) |
— | about 3 years ago |
| Question | — |
General Questions Regarding FPGAs I'm curious about FPGAs and would eventually like to get into them sometime during the future, so I'd like to ask three broad questions to help orient myself: 1. In what applications are FPGAs the most popular? 2. With respect to RF and wireless designs, how are FPGAs typically utilized? 3. ... (more) |
— | over 3 years ago |
| Question | — |
Emitter Bypass Capacitor in a CE Amplifier How exactly is the emitter capacitor C3 helping to increase the voltage gain in the common emitter amplifier below? Is it because for AC signals the emitter looks like a short to ground and that essentially increases the voltage drop across the collector resistor? Thanks. (more) |
— | over 3 years ago |
| Question | — |
Filter Impedance Consideration In a lot of textbooks, filters seem to be designed around a matching source and load impedance. However, If I have a filter stage between an antenna and an LNA, wouldn't I want the load impedance(input to the LNA) to be large with respect to the source(antenna) in order to not attenuate the signal ev... (more) |
— | over 3 years ago |
| Question | — |
Mixers and Audio Extraction in a DCR Architecture I want to make a simple 7MHz direct conversion SSB receiver in order to materialize some RF concepts I have been teaching myself lately. My question revolves around the mixer portion. I'm failing to understand how the audio is extracted from the carrier wave. Lets suppose I want to listen to an ... (more) |
— | over 3 years ago |
| Question | — |
Purpose of emitter resistor in a common collector amplifier I see a lot of common collector amplifiers with the output taken across an emitter resistor. What is the purpose of doing it this way instead of connecting your load directly to the emitter? I should mention that I am referring to an emitter follower biased by the collector output of a previo... (more) |
— | over 3 years ago |
| Question | — |
Antenna Feed Line Question Hello, I am designing 1/4 WL strip antenna for a bluetooth chip and i had some questions regarding the 50 Ohm feed line. Right now I am using a Nordic-recommended 1.5mm trace width and a 23mm + 4mm(for tuning purposes) trace length as my antenna. My feed line is 2mm away from the antenna and th... (more) |
— | over 3 years ago |
| Question | — |
Current Flow in the OFF Time of a Switching Power Supply I am having a difficult time picturing the flow of current and the role of the capacitor during the OFF time of a buck converter. Here is my understanding so far. During the ON time the magnetic field of the inductor grows and positive charge is being stored on the top plate of the capacitor as well ... (more) |
— | over 3 years ago |
| Question | — |
LC Filter and Capacitor Considerations I've been experimenting with LC filter circuits on the output of a SMPS I recently bought because it was too high for the circuit I'm making. After hooking up many different combinations, I found that this PI filter worked best for my load: LC PI Filter I'm trying to understand why this worked ... (more) |
— | over 3 years ago |
| Question | — |
4-Layer PCB Routing Question I am designing a 4-layer PCB that has both analog and digital circuitry throughout it. The analog section involves high return currents as well as ADCs sampling the voltage across sense resistors among other things. The digital side does not have high-frequency communications - PWM at 25kHz, and a Tw... (more) |
— | over 3 years ago |
| Question | — |
Bypass Caps and High Frequency Current Return Path I was watching this video by w2aew on the function of ceramic bypass capacitors, and at 6:00 he states that high-frequency currents take the path of least-impedance and make their way to the power rail through the ceramic capacitor next to the IC. Okay, so I get the fact that the high frequency c... (more) |
— | over 3 years ago |