Memo: Active frequency filters

Frequency filters attenuate signals outside its band-pass thresholds. There are two flavors of frequency filters: active and passive. Active filters have op-amps and offer amplification, as well as impedance matching functionality, of the output signal. Passive filters are simple R-C-L networks without any op-amp. Band-pass and Band-stop construction A band-pass filter is defined as follow: A band-pass… Continue reading Memo: Active frequency filters

Memo: One-shot timer and op-amp filters

Integrators and Differentiators are basic building blocks of analog computers. They enable summation and subtraction operations (hence, the core component of them is called "operational" amplifier). For multiplication, multiple integrators are used in parallel, along with exponential and logarithmic elements (non-linear op-amp circuits), to achieve the effect via the following transformation: ln(ab) = ln(a) +… Continue reading Memo: One-shot timer and op-amp filters

Memo: Schmitt trigger

Hysteresis definition is as follow: the phenomenon in which the value of a physical property lags behind changes in the effect causing it, as for instance when magnetic induction lags behind the magnetizing force. In asymmetric bipolar power supply (such as those created by elevating a virtual ground from unipolar power source), the hysteresis can… Continue reading Memo: Schmitt trigger

Memo: Op-amp’s gain factor and noise problems

First, here's a quick cheatsheet on closed-loop gain factor for inverting and non-inverting amplifiers. The gain of inverting amplifier is given by the resistance R2 across the feedback loop divided by the resistance R1 across the forward input. A = R2/R1 Meanwhile, the gain of non-inverting amplifier is given by A = 1 + R2/R1 as… Continue reading Memo: Op-amp’s gain factor and noise problems