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  1. P

    How does a Gilbert cell drive polyphase filter?

    output impedance polyphase filter The Gilbert mixer has resistor load.(400ohm) Does the polyphase filter affect the linearity of the mixer? does the polyphase filter requires a low output impedance buffer?
  2. P

    How to evaluate the effect of higher order harmonic of LO signal in mixer simulation?

    When we simulate mixer,usually the LO signal is sine wave, but actually the LO signal may be square wave,so how to evaluate the effect of higher order harmonic of LO signal?
  3. P

    output capacitor of LDO

    output noise ldo What is the main contribution of LDO's large external output capacitor? Better transient response or low output noise? Or other reason? What about some on-chip LDO with small (<100pF) onchip output capacitor,do they have sever problems?
  4. P

    How to improve PSR of the bandgap?

    PSR of bandgap What is the reasonable power supply rejection of this bandgap structure? how can I improve PSR of the bandgap ?Thanks
  5. P

    current gain decrease in both high and low current?

    The current gain β=Ic/Ib is almost constant for moderate bias current,but if bias current is too high or too low,the β decreases,can anyone explain it ?expecially in terms of semiconductor device,thanks.
  6. P

    What kind of resistor do we use for LDO?

    In LDO,we require large resistors about 100k~200K ohm,can we use n-well resistor? How about the matching ?Thanks!
  7. P

    How about these parameters as temperature increase?

    flicker noise MOS threshold voltage? PMOS/NMOS electron mobility
  8. P

    how does one capacitor charge another capacitor?

    C1 has been connected to a voltage source V1 for a long time,at time 0,the switches switch the connection from V1 to C2,i.e. V1 is cutoff,and the two capacitor are parallel connected,what is the voltage waveform on C2? (all the capacitors and voltage source has one node connected to groud)
  9. P

    Help me out with layout of 8:1 pnp bipolar pair

    I want to layout the 8:1 pnp bipolar pair,and arrange them in 3X3 square,since all of the bipolars' collector and base are connnected to ground,I use metal 1 to connect them all,and I use metal 2 to connect the emitter of the outer 8 bipolar in a circle,also use metal2 to connect the central...
  10. P

    statement in the body of a alter

    coraddcorner When I did corner analysis,I found some parameters are not defined,but everything was OK when I simulate the same circuit without corner analysis using the same library. The simple pcf file I loaded: corAddProcess("tsmc018" "/eda/library/tsmc018/models/spectre" 'singleModelLib)...
  11. P

    How to improve LDO's transient response?

    ldo transient response I am now working on capacitor-less LDO (internal compensation,without large output capacitor) The phase margin is about 57deg,and the unity-gain bandwidth is about 3.6MHz I think it is stable enough. When I simulate the load transient response,changing the load current...
  12. P

    Help me to find this old paper?

    L. K. J. Vandamme and H. M. M. de Werd, “. 1/f. noise model for. MOST’s biased in nonohmic region,” Solid State Electron, vol. 23, pp. 325–329, 1980 Thanks very much!
  13. P

    flicker noise of MOSFET in triode region?

    mosfet triode region is the flicker noise of MOSFET in triode region much smaller than in saturate region?
  14. P

    flicker noise in upconversion mixer

    upconversion + noise It seems that it is similar to phase noise in vco but I haven't found any reference about flicker noise in upconversion mixer can you recommend some good material? thanks very much
  15. P

    constant-gm bias in short-channel device

    how can we implement constant-gm bias in 0.18um process? since the square-law does not apply to the devices when length of MOSFET is 0.18um
  16. P

    wideband limiting amplifier

    I wanna design a wideband limiting amplifier,which has around 7dB gain ,and 2G bandwidth,consumes less than 1mA current from 2V supply,would you please give some sugguestion about the structure and approach? ==Summary== Gain:7dB BW:2GHz Vdd:2V Itotal:<1mA ========= Thanks
  17. P

    How to add I/Q signal after the mixer?

    In an I/Q modulator,we use two seperate mixers to do up-conversion of I/Q signal,then how do we add these two paths together and then drive a PA?
  18. P

    Conversion gain in mixer?

    I have several questions about conversion gain in mixer 1.Does onversion gain mean power gain OR voltage gain ? 2.Does power gain always normalized to 50 ohm reistance? 3.Do we need to match the load impedance of the mixer to 50ohm if we need to connect the mixer to an off-chip filter? If...
  19. P

    how to plot id~vdsat using spectre?

    I used to use hspice to generate id~vdsat curve to help my design currently I am using spectre,and I am not famaliar with it. I tried to simulate a single NMOS, and I can plot id~vgs curve however,I tried to plot id~vdsat, in which vdsat=2*id/gm. so I wonder 1)how to generate gm, 2)how to...
  20. P

    Can you suggest backend tools?

    back end tool list I can access synopsys backend tools,while it seems there are too much for me to learn,so can you suggest the tools used in the following backend flow? a)logic Synthesis (design compiler) b)floor plan(?) c)clock tree synthesis(?) d) Placement (?) e) routing (?) f) DRC&LVS(?)...

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