Flashcards
MMIC EXAM
Cards in this deck (45)
- 1Microwave icreplaced waveguides and coaxial cables with planar components including transmission lines, discrete resistors
when the circuit is totally or partially formed on planar dielectric then it is mic - 2hybrid micmost of the circuit except the active components are on the dielectric substrate
hybrid devies are mounted afterwards - 3why high dielectric constant is desirablethat will reduce the effective wavelength inside the medium; thereby reducing the circuit dimensions
- 4why height of substrate needs to be decreased at high frequenciesto prevent radiation loss
- 5Monolithic MICall the active and passive elements are deposited within the semi conducting dielectric substrate by some deposition sechems such as epitaxy, evaporation, sputtering
semi insulating substrate has to include a semi conducting layer for all the devices and interconnections
layered silicon technology is used where layer of silicon is grown over AL2O3 wafer, since si is lossy at hogh frequency - 6advantages of mmiclow cost production;
circuit flexibility since all the elements are present on the single board.
no wire bonds and interconnections, therefore improved reliability - 7Major challenges with mmiclow q
crosstalk
less chip area is used
integration of high power sources is difficult - 8Advantages of soi cmos technologyhigh q passive components can be easily integrated
reduced crosstalk as there is isolation between device active reigion and bulk substrate.
low power consumption - 9Requirements of substrate in MICprovide mechanical support to all the discrete components
homogenous: same epsilon r over the plane
anisotropic: epsilonr should not depend on the direction
should be non dispersive;
tan delta should be small
high thermal conductivity - 10MIC disadvantagesLimited power carrying capacity
low q value
frequency limitation
movable components like filters, attenuators are difficult to implement
high isolation between adjacent circuit components - 11compare waveguide, coaxial line, and microstrip lineRW: high frequency, high power, bulky, guided wavelength increased in transmission media.
Coaxial cable: supports TEM, power handling capacity is medium, Q is low compared to waveguide
Microstrip line:, Low frequency and power handling capacity, less Q, supports quasi tem - 12Substrate integrated waveguidewaveguide filled with dielectric, compact size, low weight, dielectric loss
high q compared to that to microstrip, top and bottom connected via holes - 13zo of strip line
- 14Analysis of striplinehelmholtz wave quation
wrote the value for del by delz sq= -ksq
then since for TEM Ez, Hz=0
wave equation reduced for 2 variables - 15solution of laplace equationsolve laplace equation with boundary condition
phi will be in terms of x and y
phi = 0 at x = -a/2,+a/2, which will make sine coefficnet 0 in phi(x), and then alpha value calculated from the condition that phi(x) = 0 at a/2
get the voltage expression
then get the electric field in y direction - 16derive dielectric loss form propagation constant
- 17what are the factors on which filling fag factor value depends onsubstrate thickness, dielectric constant,frequency, conductor width
- 18value of conductor lossrs/(zo*w)
rs = underrroot((omega*u)/(2*sigma)) - 19value of effective epsilon r1+(q*(er-1))
- 20derive dielectric loss constant in mircrostrip
- 21Derive attenuation constant due to finite conductivity of conductor through perturbations approachtake total power = f(z)
diff wrt z
take alphac = f(PL, Pc)
PL = .5*integration(Rs*Js^2)
assume Js constant over conductor = I/w
Pc = .5*zo*i^2
calculate - 22WHEELERS INCREMENTAL INDUCTANCE APPROACHQsince we not know current density
express series resistamce in terms of increased inductance which is due to magnetic fields inside the conductor.
for a good conductor, imag part of imoedance = re part of imoedance
we have similarity in expressions of L and R
L = u/i^2 integration mod h^2.ds
L = ud/w
amount of recession each metallic wall due to magnetic field inside the conductor is half skin dept - 23Prove that 1/RC is the 3dB bandwidth for parallel resonance circuitdrxgd
- 24Determine q for parallel RLC circuitsddfg
- 25Determine circuit behaviour near resoonant frequency for parallel rlc cirucitincrease in the branch current, therebey effective impedance of the network is decreased
- 26Loaded and unloaded Qunloaded q affected by the external circuitry decreases the overall q. the decreased value is known as loaded q
- 27L type network Major disadvantagesQ cannot be chosen independently
- 28pi / T type networkpi type: inductor in between
T type: capacitor in between
q can be independently chosen - 29cosa.Cosb =0.5*(Cos(a+b)+Cos(a-b))
- 302sinasinbcos(a-b)+cos(a+b)
- 312cosasinbsin(A+b)+sin(A-b)
- 321 db compression pointit is that input signal level for ehich the gain of the fundamental frequency is decreased by 1 db
- 33cross modulationif the interfer is an amplitude modulated signal, then modulation transfers from the interferer to the weak or desired signal, this happens when a weak signal and a strong interferer pass through a non linear system
- 34interferer contains phase modulation but not am, does cross modulation occur
- 35intermodulationwhen 2 interfers accompany the desired signal, then at the output of a non linear system we get frequencies which are not the harmonics of f1 and f2; then the Intermodulation products will be obtained at (2f1-f2) and (2f2-f1)
- 36—eff
- 37conductor loss and dielectric lossdue to finite conductivity of the metals, due to finite alphac fields penetrate inside the conductor and dielectric loss due to epsilon r being non linear
- 38quality factormathematically it defines the total energy stored to total power dissipated per unit time; it defines the sharpness of the resonance curve
series RLC: 1/wRC
parallel RLC: wRC, R/wL - 39why inductors are used in mmic but not in icbecause in mmic ; higher frequency range is used; therby decreasing the value of inductance and hence reducing its size
- 40Desensitizationthis happens when a interferer signal accompanies the desired signal; interfere produces excursions which reduces the SNR; now after passing through a non linear circuit, the third order term produces a fundamental harmonic and gets added with the original signal; now if the gain of the 3 order term is negative, then it will start decreasing and eventually block the output even whenthe gain is non zero
- 41—45
- 42two tone teststudy for intermodulation characterisation; 2 pure siunoids of wual amplitude asre applied to the input; the relative difference between the two frequencies is small so that the im lie within the specified narrow bandwidth; which is quite opposite from the harmonic distortion
- 43Third order intercept pointINPUT level for which the magnitude of intermodulation product becomes equal to the fundamental is called thrisd order intercept point. this point is 9.6db higher than the 1 db gain compression point. that means that gain is heavily compressed at the third order intercept point.
- 44how to calculate third order intercept pointwrite slope equation between third order intercept and 1 db compression and third order intercept and fundamental take the difference, write in terms of delta p' you can get that by taking the difference between the output fundamental and IM products at way below than the 1 db compression point and then add to the input level
- 45Value of Aiip3fgf
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- Flashcards on MMIC EXAM, created by 018 Gul Naqvi on 19/09/2023.
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