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    Capacitive Load and Linearity

    Hello, I want to design an opamp that drives a capacitive load (1-2pF) with unity gain and i would like to get good linearity performance. I had some discussions with a friend and told me that as soon as my GBW should be relatively high (200MHz) in order to achieve good linearity it would be...
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    MOS Simulation Curves for analog Design

    Hello, I am new to analog design and i try to size my circuits in a structured manner. I have seen some curves here and there like gm/Id, ft*gm/Id and. Excuse me if am asking stupid question, but could you please tell me or give any references that explain the curves one should make to...
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    How to insert .l spice model files in ADS

    Hello everyone. I have a question. I have a 0.18um CMOS model file compatible with LTspice, Cadence etc. Its extension is .l and contains models for all corners of the process. Thing is i want to build a VCO and i have electromagnetically simulated and extracted the inductor models in Momentum...
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    ESD_protection_diode_in_CMOS_RFIC_process

    Hello everyone, I have one question again. I want to ESD protect an RFIC and i have to make the 2 input diodes that are gonna be connected from the input to the VDD and ground respectively. In order to make them from MOSFETS I have connected togetgher the source,gate, bulk which constitute the...
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    Spiral Inductor Q calculation

    Hello. I have simulated a spiral inductor in RF mode Momentum and i have a question regarding Q. I use 2 definitions/methods to calculate it, the one concerning the resonant frequency and the 3 dB bandwidth and the other with the imaginary over real part of the impedance. While the 2 methods...
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    [MOVED] opamp linearity at higher freqs

    hello i am trying to design an opamp for high linearity at high frequencies (100MHz) and i have used a folded cascode followed by a simple cascode at a unity gain feedback. At lower freqs the linearity is ok, but at higher frequencies it is horrible. Can you please tell me what can be possibly...
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    Mosfet parallel devices

    Hi! I am using LTspice and i noticed the No of parallel devices parameters. What does it offer exactly? Also are there any aspects of circuit performance that can be improved by using certain amounts of parallel devices? Thank you in advance Georgios
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    180 Hybrid Coupler at 20Ghz

    Hey guys I am designing a 180 hybrid (rat race) on 20Ghz. My choices are microstrip or CPW. Any ideas on what i should choose? Also any idea a about the effects on different dielectric thickneses? Any prior experience or references are welcom. Thank you in advance. George
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    channel length and cascode maximum gain point

    Hello i have designed a cascode opamp and i have one question. I use the 0.18um process and when i increase my channel length (starting from the minimum length) the maximum output gain occurs for a lower Vin. Do you have any ideas why that should happen? Shouldn't that occur for higher Vin...
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    Microstrip matching network with impedance discontinuity

    Hello guys I have a rookie question but i haven't managed to fully understand it so here it goes.. I want to transform a 50Ω source impedance to another impedance R+jX. At the end of the line there is a load impedance R-jX (the output is conjugate matched). this matching network consists of a...
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    Theoretical Question about noise figure

    High everybody I am studying circuit noise behavior and i am a little confused. I read on Gray, Hurst et.al that the noise factor has a meaning only when the source inpedance is ohmic. But in Guillermo Gonzalez's Microwave transistor amplifiers in an Appendix, noise figure for a non ohmic source...
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    how to model the cable connecting power supply to my rf board

    Hello! I would like to know how to model the cable that connects the power supply to my rf board. There will be some inductance there and i would like to see if this will affect the circuit behavior. In my case the cable will be a twisted pair, but i would like to be able to model other cables...
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    Good book with microstrip noise formulas

    Good evening I have some microstrip structures and i would like to theoritically compute their losses/noise figure . Do you have any references to suggest? thank you in advance George
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    [SOLVED] bias network instability

    Good Evening, I have a question regarding the biasing network of an LNA. K have designed for un conditional stability (Rollet and Stern criteria) and when i perform an S parameter analysis everything is fine. However when i perform a transient analysis, my bias network seems to perform a small...
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    Panasonic ADS resistor models

    Good Evening In an LNA design i have used the Panasonic ADS kit because it has some resistors i want to use. But when i change the ads resistor with the resistors from the kit, the noise figure drops. Is that possible? Usually when using resistors from manufacturers the noise is being...
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    Minimum transmission line length

    Hello Can i use a transmission line that has a length of 10 mils? Are there manufacturers that can achieve it? I want to insert a small inductance at the source of my transistor and a small transmission line is a solution. Thank you
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    Can a 10mA current pass through a 0.4mm width microstrip quarter wavelength tline?

    Hello, I am starting another thread to ask this: I have a bias matching network using radial stubs and my question is if a current of 10mA can pass through a tline with a width of 0.4mm.. Please answer me and tell me if there are any references related to this question. Thank you George
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    LNA em_ckt_co simulation

    Hello I have designed an LNA in ADS and i made the layout in order to perform the cosimulation. But results are grossly different (for example in circuit simulation the noise figure is 0.4dB while in the co simulation it tends to be 40dB and more). I suspect that i have made a serious mistake in...
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    [SOLVED] LNA simulatipon results

    LNA simulation results Hello, I designed an LNA at 1.42GHz based on the NE3210s01. My BW is 100MHz and i get the following results. Nf=0.47dB, S11=-36 at my center freq and -13db worst over the band, a gain of 17dB approximately constant over the band and S22=-6dB at my center freq and -4dB...
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    Q of Pie matching network

    Hello I am designing a matching network to transform a 50Ω source to a complex impedance 300-j450Ω. I want a BW of 100MHz. My center freq is 1.42GHz. I use the formula Q=f0/BW, to find the required Q for my matching network. It is calculated to be 14.2. But if i design it this way i cannot...

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