2SK30 datasheet, 2SK30 pdf, 2SK30 data sheet, datasheet, data sheet, pdf, Hitachi Semiconductor, Silicon N Channel MOS FET High Speed Power Switching. Category. Description. Company, Toshiba America Electronic Components, Inc. Datasheet, Download 2SK30 datasheet. Cross ref. Similar parts: KSK Quote. 2SK30 Datasheet, 2SK30 PDF, 2SK30 Data sheet, 2SK30 manual, 2SK30 pdf, 2SK30, datenblatt, Electronics 2SK30, alldatasheet, free, datasheet, Datasheets, .

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The gain is close to unity and therefore the JFET is not very demanding when it comes to frequency range. In this schematic high frequencies go to Q while low frequencies go through U and Q You can look for “Vertical Amplifier Circuits” by Tektronix.

I read about the design, dont remember where, of the input amplifier to the Tek scope. It was far more complex than I first imagined it to be.

2SK30 Datasheet(PDF) – Panasonic Semiconductor

There is a lot more to be said about JFETs. When particular JFETs are recommended for audio applications, that’s because of low noise, not poor frequency response. On Tue, Nov 17, at 2: Ciss is closely related to input voltage noise because large junctions have less noise and more capacitance.

For a 20 MHz oscilloscope, it would be difficult to find a small signal JFET which is too slow and that is why it worked. I should have looked there for answers, I will certainly give that a thorough read. On Tue, Nov 17, at Good to know as a rule of thumb for the newbie: Makes sense to use a low noise jfet for oscilloscope input, if the frequency response is overly critical.

On Tue, 17 Nov On Wed, Nov 18, at 6: Adtasheet, taking the 2SK30A as example.

From the datasheet http: So, taking the delta-Vgs from 0V to Now the only thing I’m not sure about is if I read the curves correctly. There are several curves plotted, should I measure Vgs off for a particular jfet and then use the curve that starts at that Vgs off voltage?


I can find different gm values on this plot. So the drain to source voltage and the drain current can be considered constant. Vertical input designs where the input can vary over a wide range like with differential amplifiers take special steps to maintain a constant drain current. Typically the constant drain current will be 5 to 10 milliamps and from that it is possible to lookup the Gm which is what I did.

The Vgs affects operating range but it otherwise not important; usually low Vgs JFETs are used and the drain current is set so that the offset from the input to the output of the composite amplifier is zero volts.

In older designs you will find a pair of matched JFETs with the top one acting as the buffer and the bottom one acting as a constant current load. Over temperature the Vgs of both JFETs will track preventing temperature changes from changing the offset from input to output. Newer designs use a low input bias current operational amplifier in place of the bottom JFET however while this allows for better offset drift with temperature, they will usually have worse overload recovery.

On Wed, 18 Nov Thank you again for a great answer. I’m gonna let this sink in and study the schematic armed with this. Some day I’ll figure it out: This cannot be undone. The Group moderators are responsible for maintaining their community and can address these issues. Your email is included with the abuse report. Search Only Within This Topic.

Ian van der Neut. Hello all, Short version: Some people may remember my HV multiplier problem with my from a little over a year ago. At about that time I bought a Goldstar OSA oscilloscope from a thrift store, hoping it would help me a little to fix the However, it turned out to be broken as well, but did show a trace.

After months of stumbling around I found the jfets at the beginning of the vertical amplifiers to be faulty both channels. See schematic at http: It turned out that Vgs of the jfet I used was too high. I found one of the same type that had a lower Vgs and it worked, but I only had one that had low enough Vgs, not enough to fix both channels, besides, the max.


So I set out to find some jfets with the same low Vgs less than 2 volts, closer to 1. I found a couple and bought two types: When I got them in, and was trying to decide whether to use the 2SK30A or the 2SK first I discovered that they’re both for “audio frequencies”. Since this is a 20MHz scope I panicked a little.

2SK30 Datasheet PDF – Toshiba

So I looked back at the datasheet of the original 2SK jfet and it says right there on the front page: The look of panic on my face was replaced by the look of deep confusion.

I chose the 2SK30 since it’s input capacitance is closer to the original 2SK and the scope seems to be working fine. Rising edges of square waves are nice and vertical.

So how is it that a jfet specified for low frequencies can be used for 20MHz bandwidth scope? How is it that this scope works with this jfet at all? I realize 20MHz ain’t all that much, but it’s quite a bit higher than “audio” I would think. Circuit description from the manual: Signal from the input attenuator is connected to source follower Q When excessively high-amplitude signals are applied to the source follower, the signals will be Q and the gate-source junction of Q And the signal of Q base is converted from a single-ended signal to a paraphrase signal by differential amplifier.

On Wed, Nov 18, at On Wed, Nov 18, at 9: On Fri, Nov 20, at 8: Are you sure you wish to delete this message from the message archives of TekScopes groups.

Pioneer SA900 recap /refurbishment, FET 2SK30Y question

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