Current Feedback Amplifiers (CFB)

We often misunderstand current feedback amplifiers, although they have been available for many years!

Current Feedback (CFB) operational amplifiers (Op-Amps) have been around for more than 30 years. They were designed for extreme high-speed performance, which Voltage Feedback (VFB) amplifiers could not accomplish at that time. 

CFB amplifiers have one major advantage over VFBs, they maintain their bandwidth over a wide range of signal gain. Note that VFB amplifiers are gain-bandwidth dependent, meaning their bandwidth decreases with increasing signal gain.

In practice, CFB amplifiers are commonly used in high-speed applications while VFB amplifiers are preferably used in precision applications.

Now see the figures below (click image to enlarge):

A VFB amplifier has two symmetrical, high-impedance inputs. The fact that the negative input is high-impedance makes the feedback network, driven by the output voltage VO, operate in Voltage-Source mode.

Here the series source impedance of this voltage source is the parallel circuit of RF and RG. The output of this voltage source is connected to the inverting input, providing the voltage potential, vn, at this pin.

The voltage potential at the non-inverting input, vp, is identical to the signal input voltage VI. Thus, the difference between the two input potentials is an error voltage, ve, that is amplified to generate VO.

However, unlike the VFB amplifier, the CFB amplifier has asymmetric inputs. Internally the non-inverting input connects using a unity-gain buffer to the inverting input. Thus, the non-inverting input exhibits the high impedance of the buffer input, while the inverting input presents the low impedance of the buffer output to the feedback network.

This low input impedance makes the feedback network operate in Current-Source mode. The parallel source impedance of this current source again is the parallel circuit of RF and RG.

During normal operation, the input voltage VI drives a current, ip, into the non-inverting input, and the output of the feedback current source drives a current, in, into the inverting input. The difference between the two input currents is the error current, ie. This error current is driven into an internal high-impedance stage, which results in the output voltage, VO.

To summarize, the major difference between a VFB and a CFB amplifier is the type of input error signal generating the output voltage. A VFB op-amp uses an error voltage while a CFB op-amp uses an error current.

⇲ REFERENCE: RENESAS Application Note AN1993 Rev.0.00, May 31, 2018

OK, current feedback op-amps can be successfully used in a variety of applications. More to come later!

Intelligent Power Module (IPM)

Power semiconductor devices play a significant role in modern power control and drive systems, and one of the most common devices used in these systems is the IPM module.

An IPM (Intelligent Power Module) is in fact a powerful integrated circuit module used for controlling and driving high-power electronic devices such as AC motor drivers, inverters, frequency converters, etc. It is a highly integrated semiconductor device that typically includes multiple functional modules such as power switches, drive circuits, protection circuits, and control circuits.

So, IPM is an acronym for Intelligent Power Module, a general term for modules that combine discrete semiconductors such as IGBTs and MOSFETs with driving circuits, protection circuits, and other circuitry.

Since the driving conditions and protection functions are optimized for the built-in power devices, and because they are easy to use, they are called Intelligent Power Modules (IPMs),

Keep note at this point that the key difference between Power Modules and IPMs is that a power module incorporates multiple discrete semiconductors in a single package, but a driving circuit and a protection circuit must be provided separately.

That is, an IPM typically includes a power MOSFET, IGBT, or SiC(Silicon Carbide) switch device, as well as a drive circuit for controlling the conduction and cutoff of these switch devices.

In addition, IPM modules often integrate features such as power supply circuits, current and voltage sensors, over-temperature protection, and short-circuit protection.

These functions provide comprehensive protection measures to ensure the safety and reliability of high-power electronic devices.

As an example of a widely used IPM, here is the PDF DATASHEET ↗ of a 600V IGBT IPM.

The aforementioned IPM (BM63563S-VA/-VC) is an intelligent power module (3phase DC/AC Inverter) composed of gate drivers, bootstrap diodes, IGBTs, flywheel diodes. Low saturation voltage IGBTs optimized for low speed switching drive (to 6kHz) such as a compressor is adopted.

As an aside, the HSDIP25 is a long pin type package for intelligent power modules (IPMs). See this PDF ↗ for more IGBT-IPM details from ROHM Semiconductor.

To be continued ⪫⪫⪫

Audio Filters Guide

An audio filter is one of the most essential building blocks of audio electronics, and it is a processing technique used to manipulate sound signals in a specific manner.

An audio filter can modify the frequency response of an audio signal, change its tone or texture, remove unwanted noise or artifact, or enhance specific aspects of the audio. 

In essence, an audio filter is a hardware device or software program that is designed to filter the frequency characteristics of an audio signal. The basic idea behind a filter is exactly as it sounds - they filter some frequencies out, and let others remain. 

With audio filters, we can filter specific frequencies, or whole groups of frequencies, known as bands. You can see them everywhere in the audio world, but to use them, you have to know how they work, and which filters are best for each purpose.

First off note that there are many different types of audio filters, including low-pass filters, high-pass filters, band-pass filters, and notch filters, among others.

Each type of filter has its own unique characteristics and can be used for different purposes in audio processing.

⪫ A low-pass filter (LPF) is a type of audio filter that allows low frequency signals to pass through, but blocks or attenuates high frequency signals.

⪫ A high-pass filter (HPF) is a type of audio filter that allows high frequency signals to pass through, but blocks or attenuates low frequency signals.

⪫ A band-pass filter (BPF) is a type of audio filter that allows a specific range of frequencies (also known as a band) to pass through, while blocking frequencies below and above this range.

⪫ A band-stop filter is a filter that allows us to let everything pass, while selecting a band of frequencies to remove

⪫ A notch filter is a filter that allows us to remove or reduce a specific frequency (this is similar to the band-stop filter, but it focuses on a targeted frequency precisely).

In other words:

⪫ A low-pass filter passes low frequencies and cuts or filters out high frequencies.

⪫ A high-pass filter is useful to cut low frequencies, so it  is sometimes called a low cut ( the same way a low-pass is occasionally called a high cut).

⪫ A band-pass filter can be useful for isolating a particular range of frequencies in an audio signal, or for shaping the tonal character of a sound by boosting or cutting a specific range of frequencies.

⪫ A band-stop filter is the opposite of a band-pass filter.

⪫ A notch filter is similar to a band-stop filter. It is called a notch filter because it creates a notch (or dip) in the frequency response at the target frequency, effectively attenuating or cutting that frequency.

Now you’ll know what common audio filters are and how to use them.

Wikipedia https://en.wikipedia.org/wiki/Audio_filter

Well, stay tuned to get more helpful pointers for creatively shaping the tone of your sounds in sound design.

Spoiler Alert ⨶  There are thousands of ways you could apply audio filters creatively!

Reference Source - https://www.native-instruments.com/en/

Ring Radiator (Audio)

Ring Radiator is a radical revolution in domestic audio technology.

A ring radiator, also known as a ring speaker, is a type of tweeter that differs from traditional high-frequency transducer, which differs from the traditional dome loudspeakers.

Its distinctive design incorporates the utilization of a ring-shaped diaphragm in place of the conventional dome.

The design also allows for an even distribution of sound, which results in a more natural and detailed sound quality.

In Hi-Fi audio systems where sound quality is of primary importance, the ring radiator will prove to be an adequate solution.

It is a characteristic of traditional tweeters that they are prone to generate distortion at higher volume levels.

But the ring radiator’s distinctive design ensures minimal distortion, thus facilitating a more natural sound even at high volumes.

Thus, the capacity of the device to reproduce treble without distortion permits users to enjoy music of the highest quality.

Now see the Scan-Speak Ring Radiator Tweeters Datasheet PDF

The area of audio technology is perpetually engaged in an ongoing pursuit of excellence.

Audiophiles and those with a keen interest in audio and music are consistently seeking out equipment that will provide them with the optimal listening experience.

One of the most recent developments in this field is the ring radiator.

Here you will see an an article that examines the nature of a ring radiator, the advantages of utilizing such a device, and the reasons why a domestic audio system comprising one is capable of producing a superior audio experience which sounds better than ever before ↓

https://dioraacoustics.com/en/ring-radiator-a-radical-revolution-in-domestic-audio-technology/