Articles - Signal Processing, Filters

High school trigonometry combined with four-quadrant multipliers can be exploited to yield sinusoidal frequency doublers. Nothing non-linear is involved, which means no possibly strident filtering requirements. Starting with some sinusoidal signal ...

From the micromixer topology by Barrie Gilbert [ 1 ], this amplifier allows a single-ended input to be converted to a Class A/B current output from a single supply. As shown in Figure 1 with an LTspice implementation, the circuit employs 6 bipolar ...

Capturing transient analog signals with a microcontroller normally involves adding a full-fat peak-hold circuit as an external peripheral. This novel approach minimizes that extra hardware by using a µP’s ability to switch its pins ...

A previous article suggests that most digital output waveforms follow a nearly Gaussian profile ( Reference 1 ). Let’s test that theory. Figure 1 depicts the rising edge from a Texas Instruments DL100-44T LVDS ...

Which step in Figure 1 best approximates the digital signals you work with every day? The piecewise-linear step starts with a jerk, mindlessly follows a perfectly uniform ramp, and smacks hard into its upper limit. Real signals don’t do that. ...

Filtering occurs frequently in the analog world. Unfortunately, in the digital world, engineers apply it mainly to the DSPs (digital-signal processors) and not to the small 8-bit microcontrollers that designers commonly use. This situation occurs ...

Designers use PSpice mainly to simulate analog circuits. However, you can also simulate digital filters with it. The main components in a digital filter are delay elements, adders, and multipliers. Although you can implement adders and multipliers ...

There are two basic filter topologies that everyone recommends when they start to design their signal chain: multiple-feedback (MFB) or Sallen-Key topologies. But what are the differences and why would you choose one over the other? MFB filtering ...

Simplicity and low cost sustain the popularity of passive PWM DAC ripple filters despite their limitations. One of these limitations is a high output impedance caused by the series sum of filter resistance(s) (R F in Figure 1, one resistor for each ...

Several years ago I wrote an article in Design Ideas called “Double µC’s PWM frequency resolution” ( Reference 1 ) where I mentioned how one can decrease the output ripple of a PWM-based DAC using two PWM signals having ...