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  1. P

    LNA gate bias with resistor or inductor?

    Hi, guys: For an X-band MMIC LNA with phemt, can the gate be biased with TFR(thin-film resistor) instead of inductor & microstip, since the TFR can save much die area. I found the TFR model in the design kit is very different from resistor, E.G. a 20K ohm resistor will be no more than 1K...
  2. P

    Current bring down when low Vramp

    Hi,guys, measureing a GSM PA with low Vramp (0.5V) in burst mode, when RF source on, the current will be about 5mA less than quiescent current? But when Vramp>0.6V, the current will be reasonablly larger than quiescent current. Why ?
  3. P

    GSM PA burst Pout is not regular

    gsm pa The GSM PA in burst mode has an irrugular Pout shape as the attached pic., Could anyone explain it? Thx a lot!
  4. P

    LNA for DBS LNB design?

    lnb design hello,I want to know how much gain does the LNA have? On the market, most of the LNBs have a NF of lower than 0.7dB, which transistor or MMIC are usually used? NEC3210 series or any other? If the discret low noise transistor is used, maybe we need 2 or 3 stages to design the LNA, so...
  5. P

    Which to choose for RC low pass filter: NMOScap or MIMcap?

    hi, i need a capacitor more than 4pF to construct a RC low pass filter, i have an alternative between NMOScap and MIMcap. Would any guys give me some advices? which one is better?
  6. P

    why the input and output DC voltage are equal?

    as the fig. shows, can some guys explain it? thx in advance!
  7. P

    A question about impedance matching

    For the maximum power transmission, we use conjugate matching. Observing from the 50 ohms load, the output impedance is also 50 ohms. My question is coming that only half of the power can be obtained by the load, for an amplifier, that is to say half of the power is lost. I know it is a...
  8. P

    overdrive voltage (Vgs-Vth)?

    overdrive voltage In 0.18um CMOS process, with supply voltage of 1.8V. How much of the overdrive voltage to assure the MOS in saturation? Is it reliable of 80mV?
  9. P

    linear input current range of Transimpedance AMP.?

    transimpedance amp I am a beginner on TIA design, would someone tell me that if it is possible to get a linear input range of ±40uA for such a TIA: 1.+1.8V power supply 2.transimpedance of 15KΩ (single ended) 3.differential output PS:Is it possible to get a max input current range(Saturation)...
  10. P

    RGC input stage of TIA?

    The following figure is a TIA with RGC input stage. I want to know if the DC voltage of node A should be the same as output node? however, if the currents in R1 and I1 are not equal, there must be some voltage drop on Rf. How to avoide this?
  11. P

    linear input current range simulation?

    when simulating the linear input current range,i use "AC" analysis in spectre, however,the gain is sheerly linear no matter how much the input current is. and the output voltage can even be up to several volts and exceeds the supply voltage. what is the matter?
  12. P

    Gain measurements for LNA?

    Measure the gain of LNA by network analyzer and noise analyzer respectively, but there is about 1dB difference between the two results.Actually, it is about 1dB lower when measured by noise analyzer. What's the reason? Should i only trust the S21 measured by network analyzer? and only use the...
  13. P

    How about this kind of negative feedback

    Between source node and ground,there is a network constructed by an inductor in series with a capacitor.If the inductor-capacitor network has a resonance frequency in operation band, it can supress the outband gain,improve the stability and widen the operation band。 Is it possible?
  14. P

    multi-channel transimpedance amplifier

    many papers and products of transimpedance amplifiers have thhe bandwidth of upto several Ghz, however, the multi-channel TIA has so narrow bandwidth, what is the reason? what should i pay more attention to when designing multi-channel TIA? Here are the datasheets of 4/12/16channel TIA
  15. P

    A question of Active Current Mirror

    On pp.148-149 of Razavi's "Design of Analog CMOS Integrated Circuits" I am confused that there is a conflict with KCL at Vout node. At another hand, as it is said in this part, the currents of M3 and M4 increase, how can i be possible to equal the current source Iss?
  16. P

    a question about W/L

    the attached pic. is a slice from book"Analog Design Essentials", I can not understand why it is 8 in the highlighted sentence, I think the W/L may be 16 instead of 8?
  17. P

    what's the function of this circuit?

    Thanks in advance!
  18. P

    how about designing a Quad band PA in one die

    There are two PA dies in Most Quad band PA(GSM850,GSM900,DCS,PCS) ,one for GSM850&GSM900,the other for DCS&PCS,How about design them in one die,select respective input and output matching networks by an analog switch?
  19. P

    Input matching for GSM PA design

    Whether the input matching and output matching are off chip or not?To bring down input VSWR,I have to place two indcutors off the chip,one in series,the other is shunt,but I thought it cost too much space in the module, I also tried this method:use an inductor(bond wire) in series with the...
  20. P

    what's the difference between these package?

    LGA,MLF,QFN,QFP? IS all LGA package based on laminated substrate? what are the merits and shortages of each package above? For GSM PA,what kind of package would be preferred?

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