Embedded Systems Conference
Breaking News
Newest First | Oldest First | Threaded View
User Rank
re: Discrete audio amplifier basics - Part 2: JFETs, MOSFETs and other circuit configurations
kendallcp   7/20/2010 12:34:31 PM
It's lovely to see such extended treatment of JFET amplifiers. How many other people out there get the same rather wistful feeling that I do, though? The big semiconductor manufacturers have culled their JFET ranges to extinction, leaving the market mostly to specialist vendors such as Linear Systems. Depletion-mode FETs have the wonderful characteristic of being conducting when no gate potential is applied; this behaviour is really hard to replicate otherhow. There are a few depletion MOS devices out there; single-source and in quite large packages. I feel rather sad that the JFET is slowly fading from our design consciousness. What do you think?

User Rank
re: Discrete audio amplifier basics - Part 2: JFETs, MOSFETs and other circuit configurations
WKetel   4/1/2010 12:18:46 AM
This explanation of the symbols is useful. Now I need to convince others that it has value.

User Rank
re: Discrete audio amplifier basics - Part 2: JFETs, MOSFETs and other circuit configurations
bcarso   3/28/2010 8:09:16 PM
You need to establish a base bias suffficent to operate the lower device in/near the pinchoff region, i.e., where its output impedance is reasonably high. You do not want the base voltage to (partially) track with the circuit output voltage---this tends to defeat the purpose of the cascade, which is to minimize the voltage swing on the drain of the input device, thus reducing drain-gate capacitance multiplication ("Miller effect"). In some cases it is advantageous to derive the base voltage from a sample of the actual circuit input voltage, reducing the effective FET input capacitance further---however, this will result in negative input impedance at high frequencies and potential instabilities.

User Rank
re: Discrete audio amplifier basics - Part 2: JFETs, MOSFETs and other circuit configurations
wreeve   3/28/2010 4:39:18 AM
I would like to explore the cascode configuration of fig. 9.15 but with Q2 replaced with a BJT. My question concerns biasing of Q2 when it is a BJT in a common base configuration. Does it matter if the base biasing resistor is connected directly to Vcc or the bottom of R2 where the Output is tapped? How do both arrangements affect the overall cascode circuit gain?

Most Recent Comments
Most Recent Messages
8:25:34 AM
Top Comments of the Week
Like Us on Facebook

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
EE Life
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More
Max Maxfield

My Mom the Radio Star
Max Maxfield
Post a comment
I've said it before and I'll say it again -- it's a funny old world when you come to think about it. Last Friday lunchtime, for example, I received an email from Tim Levell, the editor for ...

Bernard Cole

A Book For All Reasons
Bernard Cole
Robert Oshana's recent book "Software Engineering for Embedded Systems (Newnes/Elsevier)," written and edited with Mark Kraeling, is a 'book for all reasons.' At almost 1,200 pages, it ...

latest comment mjlinden Thanks for your input!
Martin Rowe

Leonard Nimoy, We'll Miss you
Martin Rowe
Like many of you, I was saddened to hear the news of Leonard Nimoy's death. His Star Trek character Mr. Spock was an inspiration to many of us who entered technical fields.

Rich Quinnell

Making the Grade in Industrial Design
Rich Quinnell
As every developer knows, there are the paper specifications for a product design, and then there are the real requirements. The paper specs are dry, bland, and rigidly numeric, making ...

Special Video Section
After a four-year absence, Infineon returns to Mobile World ...
A laptop’s 65-watt adapter can be made 6 times smaller and ...
An industry network should have device and data security at ...
The LTC2975 is a four-channel PMBus Power System Manager ...
In this video, a new high speed CMOS output comparator ...
The LT8640 is a 42V, 5A synchronous step-down regulator ...
The LTC2000 high-speed DAC has low noise and excellent ...
How do you protect the load and ensure output continues to ...
General-purpose DACs have applications in instrumentation, ...
Linear Technology demonstrates its latest measurement ...
Demos from Maxim Integrated at Electronica 2014 show ...
Bosch CEO Stefan Finkbeiner shows off latest combo and ...
STMicroelectronics demoed this simple gesture control ...
Keysight shows you what signals lurk in real-time at 510MHz ...
TE Connectivity's clear-plastic, full-size model car shows ...
Why culture makes Linear Tech a winner.
Recently formed Architects of Modern Power consortium ...
Specially modified Corvette C7 Stingray responds to ex Indy ...
Avago’s ACPL-K30T is the first solid-state driver qualified ...
NXP launches its line of multi-gate, multifunction, ...
EE Times Senior Technical Editor Martin Rowe will interview EMC engineer Kenneth Wyatt.
Flash Poll