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Compensation for Error Caused by Limited Gain-Bandwidth of Operational Amplifiers in Low-pass Filters

Circuit design *Manufacture and development of electronics *DIY Electronics for beginners
Tutorial
Amateur vs Pro

An operational amplifier has the internal compensation circuit for stability which limits its working bandwidth. Frequency response of the compensated Op Amp has slope of −6 dB/octave or −20 dB/decade. Unity gain frequency defines the bandwidth where the Op Amp is able to amplify a signal. If we multiply the gain and frequency at any point, the result is the same, allowing us to use this parameter to select the appropriate Op Amp. It is called Gain-Bandwidth Product, GBW or GBP. The limited open-loop gain introduces a closed-loop gain and phase error.

But we want to optimize our circuits, right?
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Total votes 8: ↑8 and ↓0 +8
Views 1.8K
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Active Termination Drivers

Circuit design *Manufacture and development of electronics *DIY Electronics for beginners
Tutorial


The easiest way to build a driver with specified output impedance is to use an amplifier with high load compatibility and add a resistor to its output. The penalty is a voltage drop across this resistor, so there is power loss and we need a higher supply voltage. If our driver is able to deliver the same voltage and current to the same load, but the extra resistor will have a lower value, our device will be able to deliver the same output power at a lower supply voltage. Less power losses, less heat, and longer working time when a battery is used.
There is an idea how to solve this problem: active termination. We can synthesize the output impedance!

Now when we know what we want, go to design our drivers!
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Total votes 6: ↑6 and ↓0 +6
Views 1.7K
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Gyrators

Circuit design *Manufacture and development of electronics *DIY Electronics for beginners
Tutorial


Gyrators are impedance converters usually used to simulate inductance in circuits. Though they are rarely used in discrete electronics, they are interesting circuits looking like pole dancers in pictures. There are studies on gyrators, but still something is missing, so it is interesting to do another one.
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Total votes 4: ↑4 and ↓0 +4
Views 1K
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A note on small-signal modeling of SEPIC CM CCM

CAD/CAM *Circuit design *Manufacture and development of electronics *DIY Electronics for beginners
Tutorial

Knowing parameters of small-signal control-to-output transfer functions makes it easier for engineers to design compensation networks of DC/DC converters. The equations for SEPIC can be found in different works and Application Notes, but there are differences. A work has been done to solve this problem.

Simplified design equations for SEPIC with Current Mode control (CM) in Continuous Conduction Mode (CCM) suitable for practical design of compensation networks are shown.

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Total votes 3: ↑3 and ↓0 +3
Views 1.1K
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