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Recent content by Colon

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    Norton Amp with Augmentation (Trask)

    Thanks again. This does look quite good actually, although we would have to run some tests as not all the parameters are specified. We're looking at HF comms. - - - Updated - - - One other thing, our existing amp has NF < 2dB. I can't find anything about NF on the device you suggest, but I...
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    Norton Amp with Augmentation (Trask)

    Thanks for that. They do look good but I don't think they are quite good enough performance for us. The key point I think is that they are quoting output referred IP2 and IP3. My figures above were input referred, with 7 dB of gain, and we are looking to improve on that so I don't think a MMIC...
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    Norton Amp with Augmentation (Trask)

    Even in the HF band?
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    Norton Amp with Augmentation (Trask)

    Ok thanks, that's not quite what I'm looking for though. I am working with specs around P1dB >25dBm, with IIP2> 80 and IIP3 > 45dBm. Sometimes the older technology is what you need. Thanks James
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    Norton Amp with Augmentation (Trask)

    Hi, I have a Norton amp that works over the HF band with reasonable distortion and was thinking of trying Chris Trask's method of augmentation (see attached paper) to see what kind of improvement I could get. I see I can use passive augmentation with a transformer with appropriate turns ratio...
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    HOW TO SETUP FORWARD & REVERSE BIAS for PIN DIODE in MWO

    I have been reading some more on PIN diodes today. I keep going back to my original design which is effectively a shunt attenuator. This is the setup in the attached picture. I was trying to vary the PIN diode resistance with a, appropriate froward current, from Vbias. The only thing that...
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    high power pin diode limiters

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    high power pin diode limiters

    Ok, so the concept is that we have to limit signals from the antenna to +26dBm and as it's near a transmitter we are likely to see signals up to about 50dBm potentially. The guy originally assigned to make the limiter started off with a clipping limiter but that wasn't working so well so we are...
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    high power pin diode limiters

    Hi, I think I know what is going on here, but I could do with some reassurance and direction if possible please. We are trying to make a high power PIN diode limiter, for use in the HF band. Our spec says we need to able to limit RF output power at 26dBm for up to a 46dBm input! We have...
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    op amp problem - sudden high input bias current with large signal input

    Actually, I think you might be onto something there. This opamp doesn't have clamping diodes to limit the differential input I don't think. And, I was measuring and simulating a differential input voltage outside of the specified limits under large signal conditions. So, I added clamp diodes to...
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    op amp problem - sudden high input bias current with large signal input

    Ah ok, sorry I misunderstood. I can give it a go for sure. You're right, the values are 10uF. I am using a pair of BJT transistors as a Vbe multiplier and to bias the two output push pull transistors on. Each of these is then bypassed at signal frequencies by 10uF to improve linearity. The two...
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    op amp problem - sudden high input bias current with large signal input

    Ok, so the output is AC coupled because I don't want to drive dc into my load, and because I am trying to pass between 10kHz and 1.5MHz I need quite a large cap. I could put a series resistor on there but I need to keep noise down so I'm not going to be able to have more than a few tens of...
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    op amp problem - sudden high input bias current with large signal input

    My range of input frequency is 10kHz to 1.5MHz. For the current tests I just happen to be using 1.5MHz. I just tested the differential input voltage and actually at the largest signal input it was going above the specified limited. I have added back to back protection diodes across the inputs...
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    op amp problem - sudden high input bias current with large signal input

    So, it wouldn't appear that there are any spikes near to the input common mode limits of the amp. I set a trigger on my scope and at no point did I see a spike. Something I have just noticed though. The behavior is dependent upon duty cycle. I am using a standard cheap function generator to...
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    op amp problem - sudden high input bias current with large signal input

    Thanks for the reply. 1. Our signal source is 50 ohms but it is actually transformed to a higher impedance of 200 Ohms before the circuit I have attached. the 300Ohms isn't a perfect match but it's still good and gives us a little more signal gain. 2. The problem occurs before this point when...
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