Circuits & Schematics - Signal Processing, Filters

Of the many types of analog filters available to designers, few allow easy adjustments of the filter parameters. The biquadratic, or biquad, filter is an exception, however. You can change that filter's corner frequency (ω 0 ), Q, and ...

Figure 1 is a cheap and cheerful voltage inverter I offered awhile back in “A simple, accurate, and efficient charge pump voltage inverter for $1” ( Ref. 1 ). Figure 1. The generic and versatile xx4053 provides the basis for a cheap, ...

As a genre, DACs are low power devices with power and current output capabilities limited to the milliwatt and milliampere range. There is, of course, no fundamental reason they can’t be teamed up with suitable power output stages, which is ...

Awhile back I published a simple design idea for a thermal airspeed sensor based on a self-heated Darlington transistor pair (Ref, 1). The resulting sensor is simple, sensitive, and solid-state, but suffers from a radically nonlinear airspeed ...

This design for a photonic switch needs more than approximately 70 V at the cathode of a duo-lateral optical position-sensing device. This voltage gets speedy response at longer wavelengths, such as 980 nm. The circuit uses fast transimpedance ...

Intrinsically capacitive transducers and other high-impedance signal sources usually require ac coupling and a buffer amplifier to condition the signal for further processing. Buffers take many forms, but most of them compromise signal quality ...

A classic analog application is the full-wave precision rectifier (absolute value) function. Many variations exist on this theme, each with its own supposed (often rather minor and sometimes downright dubious) advantages compared to competing ...

While choosing an op-amp buffer, some sources of negative supply were considered, because the buffer op-amp had to provide true zero voltage on its output. In reality, a typical rail-to-rail output op-amp isn’t capable of this, it can ...

The bandpass filter circuit shown in Figure 1 features an electronically controlled Q. Q for a bandpass filter is defined as the ratio of the 3 dB pass bandwidth to the stop bandwidth at some specified attenuation. The center frequency of the ...

An interesting variation on the theme of digital to analog converters (DACs) is the digital potentiometer (DPOT). In addition to being able to output a voltage proportional to a digital value when used as a multiplying DAC (MDAC), the DPOT can also ...