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by: Kaya Conroy


Kaya Conroy
GPA 3.85


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This 40 page Class Notes was uploaded by Kaya Conroy on Thursday October 22, 2015. The Class Notes belongs to RG ST 145 at University of California Santa Barbara taught by Staff in Fall. Since its upload, it has received 36 views. For similar materials see /class/227180/rg-st-145-university-of-california-santa-barbara in Religious Studies at University of California Santa Barbara.

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Date Created: 10/22/15
Introduction to Receivers 0 Purpose translate RF signals to baseband Shift frequency Amplify Filter Demodulate 0 Why is this a challenge Interference selectivity images and distortion Large dynamic range required SFDR Many receivers must be capable of handling a very wide range of signal powers at the input while still producing the correct output This must be done in the presence of noise and interference which occasionally can be much stronger than the desired signal Noise sets the threshold for minimum detectable signal power MDS Distortion sets the maximum signal power level The third order input intercept IIP3 is a gure of merit that is directly related to the intermodulation distortion produced by a particular design Power Volts in 509 10 dBm I 174 dBm 130 dBm 80 dBm 4x10392 W 10quot5W 1039 W IO39ZW 0 6 nV 0 1pV 32w 1V Strong local Themm noise MDS for Cellphone signal 31 input ofreslstor m good comm ofrecewer 1 Hz bandwidth RF to baseband 2 dominant architectures 7 Superheterodyne 1917 E H Armstrong Uses intermediate frequency 99 of receivers use this 7 Direct conversion Becoming more popular for single chip radios Less hardware but troublesome Both use frequency translation 7 Mixer for up or down conversion Why frequency translation The original concept in 1917 addressed current technology The vacuum tubes of that day were not capable of providing any gain above 1 or 2 MHz By using the nonlinearity of a vacuum tube along with gain at low frequencies a few hundred kHz typically receivers could be built that were sensitive in the MHz range This enabled the power level of radio transmitters to be greatly reduced Today gain is cheap but the superhet architecture has lived on and has much broader use It allows the designer to optimize the receiver performance through clever choice of intermediate frequencies and ltering Direct conversion is less common but has become recently more popular in single chip radios It can eliminate offchip bandpass lters replacing them with onchip DSP lowpass lters Receiver block diagram antenna fIF or fbaseband Front End Demodulation Frequency translation Ampli cation Selectivity Audio video digital data AM FM SSB PSK etc The front end of the receiver performs the frequency translation channel selection and ampli cation of the signal BPF Superheterodyne f f 33 fRF gt LO 1 Direct conversion fbasebmd LPF Channel selection The superheterodyne or superhet architecture uses an intermediate IF frequency following the mixer This is selected such that ampli ers and channel selection lters are available with suitable performance Image rejection also plays a role as will be seen later The direct conversion mixes down to DC The advantage is that lters can be integrated on chip using active or digital filter design approaches But LO leakage causes a DC offset Also the mixer in most cases must be a complex image rejecting design because the signal and image fold over onto the same frequency What is a mixer Frequency translation device Ideal mixer A AB Doesn t mix it multiplies A sin wltB sin wzt A B cosa1 wz t cosa1 wz t Downconvert Upconvert m1 and 32 Su ressed N0 harmonlcs rah 1 2 A mixer doesn t really mix or sum signals it multiplies them A sin wltB sin wzt 1473cosa1 wz t cosa1 wz t Note that both sum and difference frequencies are obtained by the multiplication of the two input sinusoidal signals A mixer can be used to either downconvert or upconvert the RF input signal A The designer must provide a way to remove the undesired output usually by ltering Images downconversion Two inputs RF amp Image will miX to the same output IF frequency 0 The image frequency must be removed by ltering f1F and fLO must be carefully selected DIFFERENCE OUTPUTS Image rejection ratio dBPIF desiredPIF image SUM OUTPUTS ll 11 fw fW fLO f fLOfM fLofRF Even in an ideal multiplier there are two RF input frequencies FRF and FM whose secondorder product has the same difference IF frequency FRF 39 FLo FLo 39 FIM FIF The two results are equally valid One is generally referred to as the image and is undesired In the example above the lower input frequency is designated the image Image rejection preselector BPF RF IF LO DIFFERENCE OUTPUTS SUM OUTPUTS 1 fl 1 le fIM fLo fRF fLofM fLOfRF A bandpass preselectz39on lter is often used ahead of the mixer to suppress the image signal The IF and LO frequencies must be carefully selected to avoid image frequencies that are too close to the desired RF frequency to be effectively ltered In a receiver front end outofband inputs at the image frequency could cause interference when mixed to the same IF frequency Also the noise present at the image would also be translated to the IF band degrading signaltonoise ratio Alternatively an image rejection mixer could be designed which suppresses one of the input sidebands by phase and amplitude cancellation This approach requires two mixers and some phaseshifting networks So far the spectrum exhibited by the ideal multiplier is free of harmonics and other spurious outputs spurs The RF and LO inputs do not show up in the output While accurate analog multiplier circuits can be designed they do not provide high dynamic range mixers since noise and bandwidth often are sacri ced for accuracy Channel selection filter SUM OUTPUTS il T fIF fIM fLo fRF fLofM fLOfRF A narrow band xed frequency lter crystal SAW ceramic is often used for channel selection It is easier to build a high Q narrowband xed frequency lter at a lower frequency than to build a tunable high Q high frequency lter The local oscillator tunes the front end to select the input frequency f1F fRF fLo The example shown above downconverts to a lower intermediate frequency This is the superhetrodyne approach invented by Armstrong Another choice the direct conversion architecture downconverts directly to baseband zero IF Then a simple lowpass lter is used for antialiasing an AD converter and DSP is used for demodulation Images downconversion freq freq There are two cases that apply with downconversion 7 IF freq lower than RF Case 1 L0 frequency is higher than RF frequency This places the image frequency 2 X le above the RF frequency A sharp cutoff lowpass lter LPF or bandpass lter BPF could be used to attenuate the image f1F er fLo Case 2 RF frequency is higher than LO frequency This places the image frequency 2 X le below the RF frequency 7 now inband for a LPF A sharp cutoff bandpass lter BPF must be used to attenuate the image f1F fLo er Images upconversion The upconversion cases often can use a LPF for image rejection In fact the whole reason for upconverting in a receiver is to make image rejection more effective But we see that for the same fRF the two cases give much different results Case 1 Here the L0 is higher than RF Two input frequencies produce the same IF fRF fLo f1F f1M fLo f1F The image frequency is much higher than the RF frequency This makes it easy to use a simple LPF to get signi cant image rejection Case 2 Same equations but now the L0 is lower than RF This places the IF and IM frequencies lower making it more demanding for the LPF to provide signi cant image rejection An IF lter is often used here to block potentially interfering spectral inputs from creating distortion downstream in the receiver where ampli cation is provided This function is often called a roo ng lter Images Upconversion Or alternatively if we chose to keep the same IF frequency probably a common choice since IF lters are available at only certain frequencies the picture changes slightly from cases 1 and 2 Case 3 fRF fLo f1F f1M fLo f1F Case 4 fLo 39 fRF fIF f1M fLo f1F Once again the high LO injection leads to a higher image frequency and better image rejection What is the source of the image signal Both the desired RF and interfering Image signals enter through the antenna Federal and international agencies regulate spectral usage through frequency allocations Other users of the frequency spectrum may be transmitting in bands that coincide with our image frequency Our job is to choose L0 and IF frequencies to avoid high power potential interferers in the image band commercial broadcast for example Having said the above we also have a cost consideration IF filters are available only at certain frequencies if we want inexpensive massproduced lters Here are some common ones 455 kHz 107 MHz 214 MHz 45 MHz 70 MHz There are also lters available in the VHFU HF range FM radio example BPFI preselecmr BPF2 channel selection oz 5 0 FM broadcast band 88 to 108 MHz 0 Standard IF frequency 107 MHz Image is always out of band fIMAGE Z fRF 2 fIF Worst case with high side LO rmss rm 987 108 rMAGE1094 Both the RF and IMAGE frequency will be translated to the same IF frequency With a 107 MHz IF frequency the image is always outside of the FM broadcast band Therefore strong inband FM signals are never to be found at the image frequency A preselection lter can be used to reject this image that is 214 MHz away from the desired RF signal In the usual implementation this lter is a bandpass lter with narrow bandwidth and is tuned tracking the LO frequency Why does it use LO injection on the high side above the RF in frequency AM Radio Example BPFI Preselecmr BPF2 channel selection 0 AM broadcast band 530 to 1700 KHz 0 Standard IF frequency 455 KHz Image is often inband High Q tunable per selector lter is needed Worst case with high sid rRF530 rm 985 rMAGE1400 1700 LO frequency selection we always have 2 choices image rejection and oscillator implementation affect the choice 1 FL01 FRF 39 FIF 530 455 75 KHz 1700 455 1245 KHz 2 FLOl FRF FIF 530 455 985 KHZ 1700 455 2155 KHZ LO choice 1 requires a 166 to 1 tuning range for the LO 2 only requires 22 to 1 The oscillator will be much easier to implement What about image rejection With 455 KHz IF image can be in band Potential interference problem First BPF must be very selective and tunable 0 Can we redesign the receiver to use xed lowpass preselector Upconvert Use higher FIF gtgt FRF Preselector admits entire AM band No tuning allowed What is the source of the image signal Both desired RF and image IM signals enter the receiver from the antenna The image signal if present would be generated by another spectrum user Calculate Image Rejection dB LPFl preselector Band selection L Insertion loss BPFZ channel selection X dBdecade slope Image rejection 11 1 RF 17 IF LO fMGE 10g f We will use an upconversion approach to achieve a high image frequency Let s make the preselection lter simple and cheap 2 poles give 40 dBdecade We will design according to two requirements minimum of 40 dB image rejection ratio inexpensive IF lter try 107 MHZ IF frequency Determine L0 and Image freqs Let le 107 MHz fLO lt fIF fLo gt fIF Frequency Low end High end Frequency Low end High end fRF 053 MHZ 17 MHZ fRF 053 MHZ 17 MHZ fLO 1017 90 fm 1123 124 fIM 2087 197 fIM 2193 231 fRF fLo fIF fLo fRF fIF fIM fLo fur f f T f Again 2 choices of L0 frequency f1M 7 fLO fIF The worst case image frequency with low LO injection would be for fRF 17 MHz In this case f1M 197 MHz The worst case image frequency with high LO injection would be for fRF 053 MHz In this case f1M 2193 MHz As we have seen previously the higher LO frequency will give us better image rejection LPF lter cutoff frequency must be at 1700 KHz to cover entire AM band so check image rejection to see if meet spec With 40 dBdecade we will beat the spec The lter will be 40 dB down at 17 MHz So at 2193 MHz log219317 011 attenuation 40 011 40 444 dB Dual conversion receiver 0 Used for good image rejection with high first IF frequency lowpass preselector First BPF is for image rejection Second BPF for channel selection Image rejection Selection A high rst IF frequency as shown in the previous example places the image frequency well away from the desired signal Then a simple lowpass lter can be used for preselection in some cases But this high first IF may present problems for channel selection If a narrow modulation bandwidth is used the lter bandwidth of BPFl will be small Then a high loaded Q is required with the associated high losses In order to gain added exibility in managing images and spurs as well as providing for a lower Q channel selection lter a second mixer is often used to downconvert to a much lower second IF frequency With this architecture we avoid having to trade off selectivity for sensitivity Example cellphone receiver I I BPF2 Image rejection channel fm 400 MHZ Selection fIFZ 107 MHZ fLO1 1300 MHZ fLOZ 4107 MHZ At point A we see both 400 MHZ and 2100 MHZ The output of the rst mixer contains both the down and upconversion terms 400 MHZ and 2100 MHZ The higher frequency is easily removed by BPFl BPFl must also prevent an image from passing though the second mixer At point B the IF frequency is 4107 but the image frequency would be 4214 MHZ So the bandwidth of BPFl must be small enough to reject signals at 4214 MHZ At C we have both 107 MHZ and 8107 MHZ fIFZ fLOZ 7 fm But we also get the sum term The higher frequency is easily removed by BPF2 This can be a narrow bandwidth lter for channel selection 20 Automatic Gain Control 0 Need to maintain a linear signal path to avoid distortion and to keep a constant signal level at the output 1 quot p co gt L0 Automatic gain control AGC or RSSI is used as a low frequency feedback loop within a receiver The signal amplitude is measured with a peak detector and recti ed This control voltage can then be used to control the gain of ampli er stages so that the signal path can remain linear In some cases the LNA can be switched out of the system or attenuation switched into the loop to handle strong signals The AGC path must accommodate the delay found in the filters This can make the loop unstable unless the AGC voltage to the LNA and other early stages pre filtering are suitably delayed 21 Compare Superhet with Direct Conversion Superhet 7 Benefits 1 Low cost high quality xed frequency IF bandpass lters are available 2 lf noise at IF is negligible 3 Good dwamic range with AGC 7 Challenges 1 Image and spurious signal control 2 Offchip lters consume power area 3 Power dissipation 4 Simple image control solutions LPF for example may create a strong signal overload problem 22 Compare Superhet with Direct Conversion Direct Conversion 7 Bene ts simplest receiver architecture Nb l baseband ltering can be done digitally or with active lters 7 Challenges i lf noise DC offset can be caused by L0 to RF leakage at mixer input Requires image rejecting mixer 7 precision amp Second order distortion If there is a strong input signal the second order nonlinearity creates a signal at 2f This mixes with the LO at frequency f producing another source of DC offset The susceptibility to DC offset from L0 feedthrough and secondorder distortion can be reduced by careful design The local oscillator is often set to twice the frequency and divided by 2 to avoid LO leakage Balanced circuits in the mixer and ampli er will help to suppress secondorder distortion Finally many have opted for a low frequency IF rather than a DC IF to avoid offset problems This has its own hazards with regard to image rejection 23 Direct Conversion 3 Multiplication of the input signal with a cosine function 0 YO SO X0 Xt coszc t rs x 2 x w 5 sYtslt Xltt 39 image frequency f signal superiniposes the V 39v j baseband signal and i cannot be separated any more comes from second frequency component of Xf Figure from R Vogt ETH Zurich Both positive and negative frequency components are mixed to zero frequency Their images overlap and cannot be separated 24 b Multiplication with a complex time function containing only one frequency component at fC 0 x0 has an asymmetric spectral density of the amplitude gt x0 is a complex function x0 Mag 3 Yin xt e Jm 0627th Figure from R Vogt ETH Zurich With a complex LO frequency only the positive frequency signal is mixed to baseband However the signal and its image symmetric about 0 frequency must still be separated with a complex bandpass lter These will be discussed later in the context of image reject mixer design Evenorder nonlinearity Strong iuterferers 211d order H wilted NL mm 25 Aa ml ner C0 0 LNA Figure from R Vogt ETH Zurich Suppose VomyLNA a1V1 anZZ We will then get a difference term a2 cosa1 w2t which will be at a low frequency The RF 7 IF feedthrough from the mixer allows this signal to pass through to the output If the input signal has an amplitude modulation where wm is the modulation frequency and we the carrier frequency VI A secs mmtacos wct bsin act Then the LNA output contains a a2 b2Ag cos mmt term at baseband that will corrupt the desired signal These are some reasons why minimizing secondorder distortion is very important in direct conversion receivers gt The lowF receiver The RF signal is not downconve ed to DC but to a Very low center frequency 50 ma image ram xmage magma Figure from R Vogt ETH Zurich A low IF receiver architecture eliminates the DC offset problem and reduces the l f noise problem Filtering can be done on chip with analog or digital lters 27 Harmonic Balance Simulation on ADS General Description of Harmonic Balance in Agilent ADS 1 Harmonic balance is a frequencydomain analysis technique for simulating nonlinear circuits and systems It is wellsuited for simulating analog RF and microwave circuits since these are most naturally handled in the frequency domain Circuits that are best analyzed using HB under large signal conditions are 0 O power amplifiers frequency multipliers mixers oscillators modulators o o o 000 00 O o o O Harmonic Balance Simulation calculates the magnitude and phase of voltages or currents in a potentially nonlinear circuit Use this technique to 39239 Compute quantities such as PldB thirdorder intercept TOI points total harmonic distortion THD and intermodulation distortion components 39 Perform power amplifier loadpull contour analyses 39 Perform nonlinear noise analysis 39 Simulate oscillator harmonics phase noise and amplitude limits 0 0 0 0 In contrast Sparameter or AC simulation modes do not provide any information on nonlinearities of circuits Transient analysis in the case where there are harmonics and or closelyspaced frequencies is very time and memory consuming since the minimum time step must be compatible with the highest frequency present while the simulation must be run for long enough to observe one full period of the lowest frequency present Harmonic balance simulation makes possible the simulation of circuits with multiple input frequencies This includes intermodulation frequencies harmonics and frequency conversion between harmonics Not only can the circuit itself produce harmonics but each signal source stimulus can also produce harmonics or smallsignal sidebands The stimulus can consist of up to twelve nonharmonically related sources The total number of frequencies in the system is limited only by such practical considerations as memory swap space and simulation speed The Simulation Pr 006881 FYI skip to next section if you want to get started now The harmonic balance method is iterative It is based on the assumption that for a given sinusoidal excitation there exists a steadystate solution that can be approximated to satisfactory accuracy by means of a finite Fourier series Consequently the circuit node 1 From Agilent ADS Circuit Simulation Manual Chap 7 Harmonic Balance voltages take on a set of amplitudes and phases for all frequency components The currents owing from nodes into linear elements including all distributed elements are calculated by means of a straightforward frequencydomain linear analysis Currents from nodes into nonlinear elements are calculated in the timedomain Generalized Fourier analysis is used to transform from the timedomain to the frequencydomain A frequencydomain representation of all currents owing away from all nodes is available According to Kirchoffs Current Law KCL these currents should sum to zero at all nodes The probability of obtaining this result on the first iteration is extremely small Therefore an error function is formulated by calculating the sum of currents at all nodes This error function is a measure of the amount by which KCL is violated and is used to adjust the voltage amplitudes and phases If the method converges that is if the error function is driven to a given small value then the resulting voltage amplitudes and phases approximate the steadystate solution Designers are usually most interested in a system39s steadystate behavior Many highfrequency circuits contain long time constants that require conventional transient methods to integrate over many periods of the lowestfrequency sinusoid to reach steady state Harmonic balance on the other hand captures the steady state spectral response directly The applied voltage sources are typically multitone sinusoids that may have very narrowly or very widely spaced frequencies It is not uncommon for the highest frequency present in the response to be many orders of magnitude greater than the lowest frequency Transient analysis would require an integration over an enormous number of periods of the highestfrequency sinusoid The time involved in carrying out the integration is prohibitive in many practical cases At high frequencies many linear models are best represented in the frequency domain Simulating such elements in the time domain by means of convolution can results in problems related to accuracy causality or stability Harmonic Balance Setup The HB method depends on calculating currents and voltages at many harmonicale related frequencies for each fundamental signal under considemtion Since we are interested in the steady state solution of a nonlinear problem we must allow the HB simulator to use enough harmonics so that a Fourier series constructed from these harmonic amplitudes and phases can reproduce a reasonable replica of the time domain solution Figure 1 illustrates avery basic HB simulation setup The Harmonic Balance controller speci es several key simulation parameters In the example below one fundamental frequency Freql150 MHz is speci ed as aninput The index 1 shows that only one fun amental frequency is being considered Orderl speci es the number of harmonic frequencies to be calculated 15 for the rst and only frequency in this case One of the most common errors in HE simulation setup is to use too low of an order You can HARMONIC BALANCE HarmonicBalance HB1 Freq1450 MHz determine what order is optiman if you rst simulate your circuit with a small order then increase the order in steps of l or 2 harmonics When the solution stops changing within a signi cant bound you have reached the optiman order Using too high of an order is wasteful of memory le size and simulation time so it is not ef cient to just clobber the problem with a very high order Some user discretion is advised Figure 1 Example of the HB controller used for a very simple single tone frequency simulation In addition power PIN is being swept from 10 to 6 dBm ADS does not automatically pass parameters from the schematic to the display panel Calculated node voltages are automatically transferred but the input parameters used for independent voltage current or power sources are not unless they are being swept by a sweep controller setting Then they become a parameter that is automatically passed to the display To transfer parameters from schematic to display open the controller symbol select output tab and then add the variables to the list as seen below a anc Halmacha ance lnslsnce Name i asauslm Name l SmaHSlg palm salve Dash 1 Display 4 gt 39Save by Halal2w Maximum new r7 magmas If r MeasulememEquahans 2 39Savehyname g Mammals y when 3 Zhsd controller quotquot u c in HE 39 P 39 39 i 4 i 39 39 39 39 ii i 39 sour resistance 50 ohms is included The available source power is provided as PIN in dBm which will be converted to Watts by the dbmtow fuhcu39dh and degrees ofphase F 1Tone PORTl e Num 25 0 Ohm PpoardbmtowPN D Freq450 MHz Figure 2 I m Frenuencv must be speci ed 717mg srrnulauons tlnere are Uan and Pimps sourees These are olten useol for resrstanee orrrnpeolanee z Nodes rnust be labeledln tlne lnarrnonre balanee srrnulatron m oroler to transfer Lhelr uw mm b rnustbe rnserteol from tlne Probe Components rnenu An example ofaPA output network o rnenu Insert gt WyePm Label Thls opens atextbox Where you ean enter tlne noole narne you want Lee andliload were rneasureol wrtln tlne eunentprobes as shown Ld SRLC LPlabE l Luau vluau Rl R5D NE856347NLmudE NEEEESANU Flgure 3 PA output erreurt showlng noole voltage and eurrent labels and probes Displaying results The output voltages and eurrents ealeulateol by tlne HB analysls wlll eontarn many 1 y A y V J y x11 plot arnplrtuoles or powers freq4500MHz dBm Vload 21288 o dBmVload 8 Hrrlmmlmmlmm 7 Figure 4 Spectrum in dBm is plotted for Vload You can see the 15 harmonics Often you will want to plot power in dBm If your load impedance is real you can use the dbm function in an equation If the load has a complex impedance then use the de nition for sinusoidal power Pumidgm 10 log05 realVload conjI iloadi 30 This will give you the power in dBm in all cases This is the preferred method Note that calculated quantities much below 7 100 dBm are probably not very reliable due to the limited precision of the device models To perform calculations of power and ef ciency you will want to be able to select speci c equency components The harmonic index harmindex can be used to do this If you plot your output variable in a table format you will see a list of equencies freq Pout PuutdBm 00000 Hz 00000 invalid 4500MHZ 1345m 2129 900 OMHZ 1147u 19 41 1 350GHZ 336 SH 34 73 1 800GHZ 219 8p 66 58 2 25OGHZ 2250p 86 48 2 700GHz 9339p 8027 3150GHz 1465p 8834 Figure 5 Table showing the value of Pout and PoutidBm at several harmonic frequencies The frequencies are printed in order and can be designated by an index ranging from 0 for DC to Order 7 l for the highest harmonic equency The rst frequency in the table is DC and has index 0 Fundamental is index 1 So to select the voltage at the fundamental equency for example you could write Vloadl or to select power Poutl or PoutidBml in this example The second harmonic would be Pout2 Of course we do not need to draw a table to use the index For example the DC component of the power supply voltage can be extmcted by using the 0 in VCC0 Then if the supply voltage and current were measured and passed to the output display you could calculate DC input power by mPDCreaVCC0IDCi0 To display the resulw of equations such as this you use the table or rectangular plot features in the display panel The data set must be changed to Equations as shown in order to nd the result of the calculations I Plnl Tram a M Flu Type IPlol Uplmnsl Figure 6 To plot the resulw of an equation in the data display select Equations in the data set If you want to see the time domain version of a voltage or current the display can perform the inverse Fourier transform while plotting Select the Time domain signal option You are a ding data lyom a harmonic balance simulation to a plot that only supports scalar ta How would you like to handle this data 1quot Spectlum in dB r S pecllum in dB m P Magnitude of sputum Figur e 7 When plotting HB data you must convert it to a scalar quantity dB dBm or magnitude Notice that a time domain conversion can also be performed by an FFT if requested 15 gtgt 88 10f 22 7 i 57 n l l l l l l l l l time nsec Figure 8 Example of a time domain plot from a HB simulation Once the simulation has been run the data is available on the display panel You can use equations to calculate power gain and power added efficiency Note the use of the indices once again mPoutD5 realVlaad comILLoadm mPouLdBmilD logWoutHSD P7DCrealVCCD LDCiD I eaiFPomJBMIllPIN PAEIPoui dmutuwPiNPDC mEf FmagWoumyFiDCJ Parameter Sweeps It is possible to sweep any of the independent parameters in the HB simulation To set up the sweep double click on the Harmonic Balch Controller Halmnnlc Halancel Hsimomcaslsncs laslsncs Name Hal m sweep 1pm smsiisn Nisan AA Palameiel to sweep m Sweep Type M r StallSAW r DentalSpan sml slap size 392 m Num arms H Figure 9 quot L r L lU ue swent 39 Log and the start stop and step variables or number ofpoints instead of stepsize In this exa ple 39 39 to me amprine 39 39 compression behavior The more sweep points chosen the longer the simulation time and the greater the data le size2 Power 1 PoutdBm Figure 10 A double axis plot of Pout vs Pin and PAE vs Pin for a power ampli er 2 schematic m1 indepm14000 plotvsGain PIN17288 Gain Figure l l Amplifier gain vs Pin From this plot we can see that the Plum compression input power is about 4 dBm Multiple frequency simulations Multiple frequencies or tones mainly twotone are widely used for evaluation of intermodulation distortion in amplifiers or mixers In fig 12 you can see that now two frequencies have been selected Freql and Freq2 Each frequency must also declare an order number of harmonic frequencies to be considered a HarmonicBaIance HARMONIC BALANCE I MaxOrder7 Freq1RFfreqdeltaF Freq2RFfreqdeltaF Order11 1 Order21 1 SweepVarquot P Nquot Start 5 Figure 12 HB controller example for a twotone PA simulation Thrrr In th5 mnl 450 2 MHz The frequency spaerng must be small enough that the two tones are well wlthln the slgnal bandwldth of the clrcultundertest Maxlmum order eorresponds to the hlghest order mlxlng product n m to be eonsrdered nfreql 1 mfreq2 There wlll be afrequency componentln the output l The but Often accurate order In thls ease alarger number ofspectxal products wlll be summedto estlmate the MaxOrder m lncrements of 2 and watch for ehanges m the MD outputpower When no further slgnlflcant ehange ls observed thenthe order ls large enough Klarge asymmetry ls notedln the lntermodulanon components hlgher orders are lnddcated A larger number ume Both order and oversamplmg should be lncreased unul you are convlncedthat further rnereases are not wonhwhlle eausedby ehanges m deltaF eould be evaluated by ehangrng only one yanable The avallable power Pm ls speclfledln dBm for eaeh souree frequency Was 5 RFfrEq 45m MHZ uella 2 MHZ eu 2 Ffreqrdelta 4 lepulamubmluwwlmn ularmbmluwwlmn Flgure 13 Twortone souree example Displaying Results of Multitone Simulations You can View the result around the fundamental frequencies by disabling the autoscale function in the plot and specifying your own narrow range The display below shows intermodulation producw up to the 7 11 order MaxOrder speci ed on the HB controller 50 07 50 7 4007 PoutdBm 4507 200 7 445 447 449 451 453 455 freq MHz Fig 14 We would like to study the output Voltage at the fundamental frequencies and the third order IMD product frequencies This can be selected from the many frequencies in the output data set by using the mix function The desired frequencies could be selected by RFfreq deltaF Vfundl mixVload10 RFfreq deltaF Vfund2 mixVload01 2RFfreq deltaFRFfreq deltaF VIMl miXVload21 2RFfreq deltaFRFfreq deltaF VIM2 miXVload12 The respective indices used with the mix function to select this frequency are shown to the right The indices in the curly brackets are ordered according to the HB fundamental analysis frequencies Mixer Simulations In the case ofa mixer simulation at least 2 frequencies are always needed L0 and RF Figure 16 shows an example ofthe setup used for a twotone simulation ofamixer The format is similar to that described aboVe for power ampli er two tone simulations except now 3 frequencies are required The frequency with the highest power level in this example the L0 is always the first frequency to be designated in the harmonic balance controller Other inputs follow sequencing from highest to lowest power SIMULATION CONTROL HARMONIC BALANCE Lu MaxOrder1 1 Freq1LOfreq Freq2RFfreqFspacing2 Freq3RFfreqFspacingl2 Increase the LO order and max order until there are Order33 no significant changes in the D power predictions Oversample11 Oversampling can also be increased as needed Oversample21 Oversample31 1 Figure 16 HB controller example for a mixer simulation The harmonic order should be higher for high amplitude signals For the example above the LO order is highest because it is intended to switch the mixer The RF orders can be smaller since they are rarely ofhigh amplitude compared with the LO In the case ofa mixer simulation we would like to study the output voltage at the IF frequency This must be selected from many frequencies in the output data set A particular frequency is selected by using the mix mction In this example the desired IF frequencies could be LOfreq r RFfreq FspacingZ I VIF mixVout 110 LOfreq r RFfreq FspacingZ I VIF mixVout101 LOfreq RFfreq FspacingZ I VIF ixVout 110 LOfreq RFfreq FspacingZ I VIF mixVout101 and the respective indices used with the mix mction to select this frequency are shown to the right The indices in the curly brackets are ordered according to the HB mdamental analysis frequencies Thus 110 selects 1LOfreqr 1RFfreq1 0RFfreq2


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All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.