# Tag Info

Accepted

### Active low-pass filters --- good to what frequencies?

I believe your analysis to be good. I've made sallen-key 4th order filters that cut-off around 3 MHz with absolutely no worry about performance. I don't see that 10 MHz is unachievable. It's all ...
• 465k
Accepted

### Why, in a passive circuit with a sinusoidal input, do all voltages and currents have the same sinusoidal behavior as the input?

I've been pouring my brains out and eventually I've found a nice mathematical approach to prove this and decided to answer my own question. In such a circuit, solving for any voltage/current across/...
• 727
Accepted

### What is the reason to connect 4 resistors of the same value as 2s2p? (image)

Dissipation (4x) or pulse power capability (4x) since cost can go up much faster than those capabilities— or redundancy (no single failure will cause a short or open). The latter strategy is used in ...
• 409k
Accepted

### How to filter out the switching noise from a DC/DC converter

The Measurement Technique As mentioned in the comments by some of the folks, the first thing I would make sure is appropriate is the measurement technique. Measuring power supply noise accurately ...
• 5,744
Accepted

### Is there any advantage or disadvantage of using high value capacitor instead of high value resistor in filter?

is there any disadvantage of using a high-value resistor with a low-value capacitor or vice versa? Yes. High impedance brings to mind: High-value resistors create high-impedance nodes. That wouldn't ...
Accepted

### Ripple voltage filtering capacitor

I've included a snapshot, of sorts, so that you can see what's happening better: On the main diagram, I expanded out a rectangle and placed it over to the right side so that you might see a little ...
• 78.4k

### What is the reason to connect 4 resistors of the same value as 2s2p? (image)

As the others have said, it's most likely about dissipation and pulse power. But there is also cost. If you already have a reel of 10R chip resistors of one value loaded on the pick and place machine, ...
• 79.8k

### In terms of costs of mass production: is it better to try to reduce resistances' tolerance or capacitors' tolerance?

Generally it is much cheaper to get tight tolerance resistors than capacitors. You might find that even 5% resistors are mostly within 1% since the manufacturing process for resistors has become very ...
• 24.1k

### How to filter out the switching noise from a DC/DC converter

After receiving so many good answers, I started to test them all. This is my report. Input inductor should be as close to the IC as possible (Comment by Lars Hankeln) The inductor was definitively ...
• 1,133
Accepted

### How to know if this is a band-pass filter?

Long way around the barn, but I'll get there.... Sallen & Key: "A Practical Method of Designing RC Active Filters" I want to start out by reflecting on the TR-50 paper by R. P. Sallen &...
• 78.4k

### Why, in a passive circuit with a sinusoidal input, do all voltages and currents have the same sinusoidal behavior as the input?

This is only true for uniquely solvable LTI (Linear Time-Invariant) circuits that are exponentially stable. If you have a non-ideal component (and they all are to one degree or another) you will see ...
• 409k
Accepted

• 465k

### How to know if this is a band-pass filter?

I will start with an intuitive explanation: At DC the capacitance is an open-circuit, while the inductor is a short, hence $v_o=0V$. At very high frequencies the inductor will act as an open-circuit,...
• 1,397
Accepted

### What is this following filter circuit called? (For amplifiers)

The way the capacitors are currently drawn is a bit confusing, and reflects their physical wiring rather than their actual configuration. It is helpful to redraw the circuit slightly, so the two ...
• 20.2k

### Why, in a passive circuit with a sinusoidal input, do all voltages and currents have the same sinusoidal behavior as the input?

The basic reason is that the constituent equations of ideal R, L and C components are linear, time invariant equations involving only derivatives and integrals (both linear operations) and that sine ...
• 4,098
Accepted

### Parallel RC filter on SCR gate

R2 is a "gate-cathode resistor". Visually, the schematic makes it look like R2 is about C2, but it's really about the SCR's performance. A gate-cathode resistor allows some of the SCR anode current ...
• 1,880