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Bandpass Distributed Amplifier Using High-Pass Transmission Lines Basic Question

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Junior Member level 2
Apr 11, 2015
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It is stated in several papers that if you design a DA using high-pass transmission lines, the DA would most probably act as a band-pass amplifier as the line losses degrade performance in high frequencies and decrease the gain.
I have designed a BPDA based on this concept, and I'm facing a problem I already guessed I would have: Due to the presence of the capacitors in the series arm of the T-sections that form my artificial line, the gain does not show an additive nature any more. In the conventional DA the whole point was that you could absorb the transistor parasitic capacitance into the line and add the amplified signals in all the drain nodes thanks to the series inductors. How is this supposed to happen when the line is high-pass?!
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The reason that the series capacitors of the HPF cannot be absorbed by the transistor parasitic capacitance could be when due to very high working frequency the series capacitance of the HPF is much smaller compared to the parasitic capacitance of the transistor.

Because of the input capacity of each stage, any shunt inductance would form part of a resonant tuned circuit. This means that you have to use a very low value of inductance to make sure the resonance occurred at a frequency higher then the frequency bandwidth of the DA. So you need very small series capacitors to get the line impedance back to something useful. Hence you get a lot of loss in each LC section.
As a theoretical exercise, if one designed the line impedance in the order of ohms and used common base amplifiers, so its all current driven it could work?

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