OpticalLinkBackendTx.cc revision 10447
110447Snilay@cs.wisc.edu#include "model/optical/OpticalLinkBackendTx.h" 210447Snilay@cs.wisc.edu 310447Snilay@cs.wisc.edu#include "util/Constants.h" 410447Snilay@cs.wisc.edu#include "model/PortInfo.h" 510447Snilay@cs.wisc.edu#include "model/TransitionInfo.h" 610447Snilay@cs.wisc.edu#include "model/EventInfo.h" 710447Snilay@cs.wisc.edu#include "model/electrical/MuxTreeSerializer.h" 810447Snilay@cs.wisc.edu#include "model/electrical/BarrelShifter.h" 910447Snilay@cs.wisc.edu#include "model/electrical/Multiplexer.h" 1010447Snilay@cs.wisc.edu#include <cmath> 1110447Snilay@cs.wisc.edu 1210447Snilay@cs.wisc.edunamespace DSENT 1310447Snilay@cs.wisc.edu{ 1410447Snilay@cs.wisc.edu // TODO: Kind of don't like the way thermal tuning is written here. Maybe will switch 1510447Snilay@cs.wisc.edu // to curve fitting the CICC paper, which uses results from a monte-carlo sim 1610447Snilay@cs.wisc.edu 1710447Snilay@cs.wisc.edu OpticalLinkBackendTx::OpticalLinkBackendTx(const String& instance_name_, const TechModel* tech_model_) 1810447Snilay@cs.wisc.edu : ElectricalModel(instance_name_, tech_model_) 1910447Snilay@cs.wisc.edu { 2010447Snilay@cs.wisc.edu initParameters(); 2110447Snilay@cs.wisc.edu initProperties(); 2210447Snilay@cs.wisc.edu } 2310447Snilay@cs.wisc.edu 2410447Snilay@cs.wisc.edu OpticalLinkBackendTx::~OpticalLinkBackendTx() 2510447Snilay@cs.wisc.edu {} 2610447Snilay@cs.wisc.edu 2710447Snilay@cs.wisc.edu void OpticalLinkBackendTx::initParameters() 2810447Snilay@cs.wisc.edu { 2910447Snilay@cs.wisc.edu addParameterName("InBits"); 3010447Snilay@cs.wisc.edu addParameterName("CoreDataRate"); 3110447Snilay@cs.wisc.edu addParameterName("LinkDataRate"); 3210447Snilay@cs.wisc.edu addParameterName("RingTuningMethod"); 3310447Snilay@cs.wisc.edu addParameterName("BitDuplicate"); 3410447Snilay@cs.wisc.edu return; 3510447Snilay@cs.wisc.edu } 3610447Snilay@cs.wisc.edu 3710447Snilay@cs.wisc.edu void OpticalLinkBackendTx::initProperties() 3810447Snilay@cs.wisc.edu { 3910447Snilay@cs.wisc.edu return; 4010447Snilay@cs.wisc.edu } 4110447Snilay@cs.wisc.edu 4210447Snilay@cs.wisc.edu void OpticalLinkBackendTx::constructModel() 4310447Snilay@cs.wisc.edu { 4410447Snilay@cs.wisc.edu unsigned int in_bits = getParameter("InBits"); 4510447Snilay@cs.wisc.edu double core_data_rate = getParameter("CoreDataRate"); 4610447Snilay@cs.wisc.edu double link_data_rate = getParameter("LinkDataRate"); 4710447Snilay@cs.wisc.edu const String& tuning_method = getParameter("RingTuningMethod");; 4810447Snilay@cs.wisc.edu bool bit_duplicate = getParameter("BitDuplicate"); 4910447Snilay@cs.wisc.edu 5010447Snilay@cs.wisc.edu // Calculate serialization ratio 5110447Snilay@cs.wisc.edu unsigned int serialization_ratio = (unsigned int) floor(link_data_rate / core_data_rate); 5210447Snilay@cs.wisc.edu ASSERT(serialization_ratio == link_data_rate / core_data_rate, 5310447Snilay@cs.wisc.edu "[Error] " + getInstanceName() + " -> Cannot have non-integer serialization ratios " + 5410447Snilay@cs.wisc.edu "(" + (String) (core_data_rate / link_data_rate) + ")!"); 5510447Snilay@cs.wisc.edu 5610447Snilay@cs.wisc.edu // Calculate output width 5710447Snilay@cs.wisc.edu ASSERT(floor((double) in_bits / serialization_ratio) == (double) in_bits / serialization_ratio, 5810447Snilay@cs.wisc.edu "[Error] " + getInstanceName() + " -> Input width (" + (String) in_bits + ") " + 5910447Snilay@cs.wisc.edu "must be a multiple of the serialization ratio (" + (String) serialization_ratio + ")!"); 6010447Snilay@cs.wisc.edu unsigned int out_bits = in_bits / serialization_ratio; 6110447Snilay@cs.wisc.edu 6210447Snilay@cs.wisc.edu getGenProperties()->set("SerializationRatio", serialization_ratio); 6310447Snilay@cs.wisc.edu getGenProperties()->set("OutBits", out_bits); 6410447Snilay@cs.wisc.edu 6510447Snilay@cs.wisc.edu // Create ports 6610447Snilay@cs.wisc.edu createInputPort("In", makeNetIndex(0, in_bits-1)); 6710447Snilay@cs.wisc.edu createInputPort("LinkCK"); 6810447Snilay@cs.wisc.edu createOutputPort("Out", makeNetIndex(0, out_bits-1)); 6910447Snilay@cs.wisc.edu 7010447Snilay@cs.wisc.edu //Create energy, power, and area results 7110447Snilay@cs.wisc.edu createElectricalResults(); 7210447Snilay@cs.wisc.edu // Create ring heating power cost 7310447Snilay@cs.wisc.edu addNddPowerResult(new AtomicResult("RingTuning")); 7410447Snilay@cs.wisc.edu // Create process bits event 7510447Snilay@cs.wisc.edu createElectricalEventResult("ProcessBits"); 7610447Snilay@cs.wisc.edu getEventInfo("ProcessBits")->setTransitionInfo("LinkCK", TransitionInfo(0.0, (double) serialization_ratio / 2.0, 0.0)); 7710447Snilay@cs.wisc.edu // Set conditions during idle state 7810447Snilay@cs.wisc.edu getEventInfo("Idle")->setStaticTransitionInfos(); 7910447Snilay@cs.wisc.edu getEventInfo("Idle")->setTransitionInfo("LinkCK", TransitionInfo(0.0, (double) serialization_ratio / 2.0, 0.0)); 8010447Snilay@cs.wisc.edu 8110447Snilay@cs.wisc.edu // Create serializer 8210447Snilay@cs.wisc.edu const String& serializer_name = "Serializer"; 8310447Snilay@cs.wisc.edu MuxTreeSerializer* serializer = new MuxTreeSerializer(serializer_name, getTechModel()); 8410447Snilay@cs.wisc.edu serializer->setParameter("InBits", in_bits); 8510447Snilay@cs.wisc.edu serializer->setParameter("InDataRate", core_data_rate); 8610447Snilay@cs.wisc.edu serializer->setParameter("OutDataRate", link_data_rate); 8710447Snilay@cs.wisc.edu serializer->setParameter("BitDuplicate", bit_duplicate); 8810447Snilay@cs.wisc.edu serializer->construct(); 8910447Snilay@cs.wisc.edu 9010447Snilay@cs.wisc.edu addSubInstances(serializer, 1.0); 9110447Snilay@cs.wisc.edu addElectricalSubResults(serializer, 1.0); 9210447Snilay@cs.wisc.edu getEventResult("ProcessBits")->addSubResult(serializer->getEventResult("Serialize"), serializer_name, 1.0); 9310447Snilay@cs.wisc.edu 9410447Snilay@cs.wisc.edu if ((tuning_method == "ThermalWithBitReshuffle") || (tuning_method == "ElectricalAssistWithBitReshuffle")) 9510447Snilay@cs.wisc.edu { 9610447Snilay@cs.wisc.edu // If a bit reshuffling backend is present, create the reshuffling backend 9710447Snilay@cs.wisc.edu unsigned int reorder_degree = getBitReorderDegree(); 9810447Snilay@cs.wisc.edu 9910447Snilay@cs.wisc.edu // Create intermediate nets 10010447Snilay@cs.wisc.edu createNet("SerializerIn", makeNetIndex(0, in_bits-1)); 10110447Snilay@cs.wisc.edu createNet("ReorderIn", makeNetIndex(0, out_bits+reorder_degree-1)); 10210447Snilay@cs.wisc.edu assign("ReorderIn", makeNetIndex(out_bits, out_bits+reorder_degree-1), "ReorderIn", makeNetIndex(0, reorder_degree-1)); 10310447Snilay@cs.wisc.edu 10410447Snilay@cs.wisc.edu // Create barrelshifter 10510447Snilay@cs.wisc.edu unsigned int shift_index_min = (unsigned int)ceil(log2(serialization_ratio)); 10610447Snilay@cs.wisc.edu unsigned int shift_index_max = std::max(shift_index_min, (unsigned int) ceil(log2(in_bits)) - 1); 10710447Snilay@cs.wisc.edu 10810447Snilay@cs.wisc.edu // Remember some things 10910447Snilay@cs.wisc.edu getGenProperties()->set("ReorderDegree", reorder_degree); 11010447Snilay@cs.wisc.edu getGenProperties()->set("ShiftIndexMin", shift_index_min); 11110447Snilay@cs.wisc.edu getGenProperties()->set("ShiftIndexMax", shift_index_max); 11210447Snilay@cs.wisc.edu 11310447Snilay@cs.wisc.edu const String& barrel_shift_name = "BarrelShifter"; 11410447Snilay@cs.wisc.edu BarrelShifter* barrel_shift = new BarrelShifter(barrel_shift_name, getTechModel()); 11510447Snilay@cs.wisc.edu barrel_shift->setParameter("NumberBits", in_bits); 11610447Snilay@cs.wisc.edu barrel_shift->setParameter("ShiftIndexMax", shift_index_max); 11710447Snilay@cs.wisc.edu barrel_shift->setParameter("ShiftIndexMin", shift_index_min); 11810447Snilay@cs.wisc.edu barrel_shift->setParameter("BitDuplicate", bit_duplicate); 11910447Snilay@cs.wisc.edu barrel_shift->construct(); 12010447Snilay@cs.wisc.edu 12110447Snilay@cs.wisc.edu // Create bit reorder muxes 12210447Snilay@cs.wisc.edu const String& reorder_mux_name = "ReorderMux"; 12310447Snilay@cs.wisc.edu Multiplexer* reorder_mux = new Multiplexer(reorder_mux_name, getTechModel()); 12410447Snilay@cs.wisc.edu reorder_mux->setParameter("NumberBits", out_bits); 12510447Snilay@cs.wisc.edu reorder_mux->setParameter("NumberInputs", reorder_degree); 12610447Snilay@cs.wisc.edu reorder_mux->setParameter("BitDuplicate", bit_duplicate); 12710447Snilay@cs.wisc.edu reorder_mux->construct(); 12810447Snilay@cs.wisc.edu 12910447Snilay@cs.wisc.edu // Connect barrelshifter 13010447Snilay@cs.wisc.edu // TODO: Connect barrelshift shifts! 13110447Snilay@cs.wisc.edu portConnect(barrel_shift, "In", "In"); 13210447Snilay@cs.wisc.edu portConnect(barrel_shift, "Out", "SerializerIn"); 13310447Snilay@cs.wisc.edu 13410447Snilay@cs.wisc.edu // Connect serializer 13510447Snilay@cs.wisc.edu portConnect(serializer, "In", "SerializerIn"); 13610447Snilay@cs.wisc.edu portConnect(serializer, "Out", "ReorderIn", makeNetIndex(0, out_bits-1)); 13710447Snilay@cs.wisc.edu portConnect(serializer, "OutCK", "LinkCK"); 13810447Snilay@cs.wisc.edu 13910447Snilay@cs.wisc.edu // Connect bit reorder muxes 14010447Snilay@cs.wisc.edu // TODO: Connect re-order multiplex select signals! 14110447Snilay@cs.wisc.edu for (unsigned int i = 0; i < reorder_degree; i++) 14210447Snilay@cs.wisc.edu portConnect(reorder_mux, "In" + (String) i, "ReorderIn", makeNetIndex(i, i+out_bits-1)); 14310447Snilay@cs.wisc.edu portConnect(reorder_mux, "Out", "Out"); 14410447Snilay@cs.wisc.edu 14510447Snilay@cs.wisc.edu addSubInstances(barrel_shift, 1.0); 14610447Snilay@cs.wisc.edu addSubInstances(reorder_mux, 1.0); 14710447Snilay@cs.wisc.edu addElectricalSubResults(barrel_shift, 1.0); 14810447Snilay@cs.wisc.edu addElectricalSubResults(reorder_mux, 1.0); 14910447Snilay@cs.wisc.edu getEventResult("ProcessBits")->addSubResult(barrel_shift->getEventResult("BarrelShift"), barrel_shift_name, 1.0); 15010447Snilay@cs.wisc.edu getEventResult("ProcessBits")->addSubResult(reorder_mux->getEventResult("Mux"), reorder_mux_name, 1.0); // This happens multiple times 15110447Snilay@cs.wisc.edu } 15210447Snilay@cs.wisc.edu else if ((tuning_method == "FullThermal") || (tuning_method == "AthermalWithTrim")) 15310447Snilay@cs.wisc.edu { 15410447Snilay@cs.wisc.edu // If no bit reshuffling backend is present, then just connect serializer up 15510447Snilay@cs.wisc.edu portConnect(serializer, "In", "In"); 15610447Snilay@cs.wisc.edu portConnect(serializer, "Out", "Out"); 15710447Snilay@cs.wisc.edu portConnect(serializer, "OutCK", "LinkCK"); 15810447Snilay@cs.wisc.edu } 15910447Snilay@cs.wisc.edu else 16010447Snilay@cs.wisc.edu { 16110447Snilay@cs.wisc.edu ASSERT(false, "[Error] " + getInstanceName() + " -> Unknown ring tuning method '" + tuning_method + "'!"); 16210447Snilay@cs.wisc.edu } 16310447Snilay@cs.wisc.edu 16410447Snilay@cs.wisc.edu return; 16510447Snilay@cs.wisc.edu } 16610447Snilay@cs.wisc.edu 16710447Snilay@cs.wisc.edu void OpticalLinkBackendTx::updateModel() 16810447Snilay@cs.wisc.edu { 16910447Snilay@cs.wisc.edu // Update everyone 17010447Snilay@cs.wisc.edu Model::updateModel(); 17110447Snilay@cs.wisc.edu // Update ring tuning power 17210447Snilay@cs.wisc.edu getNddPowerResult("RingTuning")->setValue(getRingTuningPower()); 17310447Snilay@cs.wisc.edu return; 17410447Snilay@cs.wisc.edu } 17510447Snilay@cs.wisc.edu 17610447Snilay@cs.wisc.edu void OpticalLinkBackendTx::propagateTransitionInfo() 17710447Snilay@cs.wisc.edu { 17810447Snilay@cs.wisc.edu // Get parameters 17910447Snilay@cs.wisc.edu const String& tuning_method = getParameter("RingTuningMethod"); 18010447Snilay@cs.wisc.edu 18110447Snilay@cs.wisc.edu // Update the serializer 18210447Snilay@cs.wisc.edu if ((tuning_method == "ThermalWithBitReshuffle") || (tuning_method == "ElectricalAssistWithBitReshuffle")) 18310447Snilay@cs.wisc.edu { 18410447Snilay@cs.wisc.edu // Get generated properties 18510447Snilay@cs.wisc.edu unsigned int reorder_degree = getGenProperties()->get("ReorderDegree").toUInt(); 18610447Snilay@cs.wisc.edu unsigned int shift_index_min = getGenProperties()->get("ShiftIndexMin").toUInt(); 18710447Snilay@cs.wisc.edu unsigned int shift_index_max = getGenProperties()->get("ShiftIndexMax").toUInt(); 18810447Snilay@cs.wisc.edu 18910447Snilay@cs.wisc.edu // Update barrel shifter 19010447Snilay@cs.wisc.edu const String& barrel_shift_name = "BarrelShifter"; 19110447Snilay@cs.wisc.edu ElectricalModel* barrel_shift = (ElectricalModel*) getSubInstance(barrel_shift_name); 19210447Snilay@cs.wisc.edu propagatePortTransitionInfo(barrel_shift, "In", "In"); 19310447Snilay@cs.wisc.edu // Set shift transitions to be very low (since it is affected by slow temperature time constants) 19410447Snilay@cs.wisc.edu for (unsigned int i = shift_index_min; i <= shift_index_max; ++i) 19510447Snilay@cs.wisc.edu barrel_shift->getInputPort("Shift" + (String) i)->setTransitionInfo(TransitionInfo(0.499, 0.001, 0.499)); 19610447Snilay@cs.wisc.edu barrel_shift->use(); 19710447Snilay@cs.wisc.edu 19810447Snilay@cs.wisc.edu // Set serializer transition info 19910447Snilay@cs.wisc.edu ElectricalModel* serializer = (ElectricalModel*) getSubInstance("Serializer"); 20010447Snilay@cs.wisc.edu propagatePortTransitionInfo(serializer, "In", barrel_shift, "Out"); 20110447Snilay@cs.wisc.edu propagatePortTransitionInfo(serializer, "OutCK", "LinkCK"); 20210447Snilay@cs.wisc.edu serializer->use(); 20310447Snilay@cs.wisc.edu 20410447Snilay@cs.wisc.edu // Reorder mux shift select bits 20510447Snilay@cs.wisc.edu unsigned int reorder_sel_bits = (unsigned int)ceil(log2(reorder_degree)); 20610447Snilay@cs.wisc.edu 20710447Snilay@cs.wisc.edu // Reorder mux probabilities 20810447Snilay@cs.wisc.edu const String& reorder_mux_name = "ReorderMux"; 20910447Snilay@cs.wisc.edu ElectricalModel* reorder_mux = (ElectricalModel*) getSubInstance(reorder_mux_name); 21010447Snilay@cs.wisc.edu for (unsigned int i = 0; i < reorder_degree; ++i) 21110447Snilay@cs.wisc.edu propagatePortTransitionInfo(reorder_mux, "In" + (String) i, serializer, "Out"); 21210447Snilay@cs.wisc.edu // Set select transitions to be 0, since these are statically configured 21310447Snilay@cs.wisc.edu for (unsigned int i = 0; i < reorder_sel_bits; ++i) 21410447Snilay@cs.wisc.edu reorder_mux->getInputPort("Sel" + (String) i)->setTransitionInfo(TransitionInfo(0.5, 0.0, 0.5)); 21510447Snilay@cs.wisc.edu reorder_mux->use(); 21610447Snilay@cs.wisc.edu 21710447Snilay@cs.wisc.edu // Set output transition info 21810447Snilay@cs.wisc.edu propagatePortTransitionInfo("Out", reorder_mux, "Out"); 21910447Snilay@cs.wisc.edu } 22010447Snilay@cs.wisc.edu else if ((tuning_method == "FullThermal") || (tuning_method == "AthermalWithTrim")) 22110447Snilay@cs.wisc.edu { 22210447Snilay@cs.wisc.edu // Set serializer transition info 22310447Snilay@cs.wisc.edu ElectricalModel* serializer = (ElectricalModel*) getSubInstance("Serializer"); 22410447Snilay@cs.wisc.edu propagatePortTransitionInfo(serializer, "In", "In"); 22510447Snilay@cs.wisc.edu propagatePortTransitionInfo(serializer, "OutCK", "LinkCK"); 22610447Snilay@cs.wisc.edu serializer->use(); 22710447Snilay@cs.wisc.edu 22810447Snilay@cs.wisc.edu // Set output transition info 22910447Snilay@cs.wisc.edu propagatePortTransitionInfo("Out", serializer, "Out"); 23010447Snilay@cs.wisc.edu } 23110447Snilay@cs.wisc.edu 23210447Snilay@cs.wisc.edu return; 23310447Snilay@cs.wisc.edu } 23410447Snilay@cs.wisc.edu 23510447Snilay@cs.wisc.edu double OpticalLinkBackendTx::getRingTuningPower() 23610447Snilay@cs.wisc.edu { 23710447Snilay@cs.wisc.edu // Get properties 23810447Snilay@cs.wisc.edu const String& tuning_method = getParameter("RingTuningMethod");; 23910447Snilay@cs.wisc.edu unsigned int number_rings = getGenProperties()->get("OutBits"); 24010447Snilay@cs.wisc.edu 24110447Snilay@cs.wisc.edu // Get tech model parameters 24210447Snilay@cs.wisc.edu double R = getTechModel()->get("Ring->Radius"); 24310447Snilay@cs.wisc.edu double n_g = getTechModel()->get("Ring->GroupIndex"); 24410447Snilay@cs.wisc.edu double heating_efficiency = getTechModel()->get("Ring->HeatingEfficiency"); 24510447Snilay@cs.wisc.edu // This can actually be derived if we know thermo-optic coefficient (delta n / delta T) 24610447Snilay@cs.wisc.edu double tuning_efficiency = getTechModel()->get("Ring->TuningEfficiency"); 24710447Snilay@cs.wisc.edu double sigma_r_local = getTechModel()->get("Ring->LocalVariationSigma"); 24810447Snilay@cs.wisc.edu double sigma_r_systematic = getTechModel()->get("Ring->SystematicVariationSigma"); 24910447Snilay@cs.wisc.edu double T_max = getTechModel()->get("Ring->TemperatureMax"); 25010447Snilay@cs.wisc.edu double T_min = getTechModel()->get("Ring->TemperatureMin"); 25110447Snilay@cs.wisc.edu double T = getTechModel()->get("Temperature"); 25210447Snilay@cs.wisc.edu 25310447Snilay@cs.wisc.edu // Get constants 25410447Snilay@cs.wisc.edu double c = Constants::c; 25510447Snilay@cs.wisc.edu double pi = Constants::pi; 25610447Snilay@cs.wisc.edu 25710447Snilay@cs.wisc.edu double tuning_power = 0.0; 25810447Snilay@cs.wisc.edu 25910447Snilay@cs.wisc.edu if (tuning_method == "ThermalWithBitReshuffle") 26010447Snilay@cs.wisc.edu { 26110447Snilay@cs.wisc.edu // When an electrical backend is present, rings only have to tune to the nearest channel 26210447Snilay@cs.wisc.edu // This can be approximated as each ring tuning to something exactly 1 channel away 26310447Snilay@cs.wisc.edu 26410447Snilay@cs.wisc.edu // Setup calculations 26510447Snilay@cs.wisc.edu double L = 2 * pi * R; // Optical length 26610447Snilay@cs.wisc.edu double FSR = c / (n_g * L); // Free spectral range 26710447Snilay@cs.wisc.edu double freq_sep = FSR / number_rings; // Channel separation 26810447Snilay@cs.wisc.edu 26910447Snilay@cs.wisc.edu // Calculate tuning power 27010447Snilay@cs.wisc.edu tuning_power = number_rings * freq_sep / (tuning_efficiency * heating_efficiency); 27110447Snilay@cs.wisc.edu } 27210447Snilay@cs.wisc.edu else if (tuning_method == "ElectricalAssistWithBitReshuffle") 27310447Snilay@cs.wisc.edu { 27410447Snilay@cs.wisc.edu // Electrical assistance allows for a fraction of the tuning range to be 27510447Snilay@cs.wisc.edu // covered electrically. This is most pronounced when the tuning range is small, 27610447Snilay@cs.wisc.edu // such is the case when bit reshuffling is applied. The electrically 27710447Snilay@cs.wisc.edu // assisted part of it pretty much comes for free... 27810447Snilay@cs.wisc.edu 27910447Snilay@cs.wisc.edu // Get electrically tunable range 28010447Snilay@cs.wisc.edu double max_assist = getTechModel()->get("Ring->MaxElectricallyTunableFreq"); 28110447Snilay@cs.wisc.edu 28210447Snilay@cs.wisc.edu // Setup calculations 28310447Snilay@cs.wisc.edu double L = 2 * pi * R; // Optical length 28410447Snilay@cs.wisc.edu double FSR = c / (n_g * L); // Free spectral range 28510447Snilay@cs.wisc.edu double freq_sep = FSR / number_rings; // Channel separation 28610447Snilay@cs.wisc.edu double heating_range = std::max(0.0, freq_sep - max_assist); // The distance needed to bridge using heaters 28710447Snilay@cs.wisc.edu 28810447Snilay@cs.wisc.edu // Calculate tuning power, which is really only the power spent on heating since 28910447Snilay@cs.wisc.edu // distance tuned electrically is pretty much free 29010447Snilay@cs.wisc.edu tuning_power = number_rings * heating_range / (tuning_efficiency * heating_efficiency); 29110447Snilay@cs.wisc.edu } 29210447Snilay@cs.wisc.edu else if (tuning_method == "FullThermal") 29310447Snilay@cs.wisc.edu { 29410447Snilay@cs.wisc.edu // If there is no bit reshuffling backend, each ring must tune to an 29510447Snilay@cs.wisc.edu // absolute channel frequency. Since we can only heat rings (and not cool), 29610447Snilay@cs.wisc.edu // we can only red-shift (decrease frequency). Thus, a fabrication bias 29710447Snilay@cs.wisc.edu // must be applied such that under any process and temperature corner, the 29810447Snilay@cs.wisc.edu // ring resonance remains above channel resonance 29910447Snilay@cs.wisc.edu // I'll use 3 sigmas of sigma_r_local and sigma_r_systematic, and bias against 30010447Snilay@cs.wisc.edu // the full temperature range 30110447Snilay@cs.wisc.edu double fabrication_bias_freq = 3.0 * sqrt(pow(sigma_r_local, 2) + pow(sigma_r_systematic, 2)) + 30210447Snilay@cs.wisc.edu (T_max - T_min) * tuning_efficiency; 30310447Snilay@cs.wisc.edu 30410447Snilay@cs.wisc.edu // The local/systematic variations are 0 on average. Thus, the tuning distance can be calculated as 30510447Snilay@cs.wisc.edu double tuning_distance = fabrication_bias_freq - (T - T_min) * tuning_efficiency; 30610447Snilay@cs.wisc.edu 30710447Snilay@cs.wisc.edu // Tuning power needed is just the number of rings * tuning distance / (tuning and heating efficiencies) 30810447Snilay@cs.wisc.edu tuning_power = number_rings * tuning_distance / (tuning_efficiency * heating_efficiency); 30910447Snilay@cs.wisc.edu } 31010447Snilay@cs.wisc.edu else if (tuning_method == "AthermalWithTrim") 31110447Snilay@cs.wisc.edu { 31210447Snilay@cs.wisc.edu // Athermal! Each ring's process variations are trimmed! Everything is free! 31310447Snilay@cs.wisc.edu // Basically an ideal scenario 31410447Snilay@cs.wisc.edu tuning_power = 0; 31510447Snilay@cs.wisc.edu } 31610447Snilay@cs.wisc.edu else 31710447Snilay@cs.wisc.edu { 31810447Snilay@cs.wisc.edu ASSERT(false, "[Error] " + getInstanceName() + " -> Unknown ring tuning method '" + tuning_method + "'!"); 31910447Snilay@cs.wisc.edu } 32010447Snilay@cs.wisc.edu 32110447Snilay@cs.wisc.edu return tuning_power; 32210447Snilay@cs.wisc.edu } 32310447Snilay@cs.wisc.edu 32410447Snilay@cs.wisc.edu unsigned int OpticalLinkBackendTx::getBitReorderDegree() 32510447Snilay@cs.wisc.edu { 32610447Snilay@cs.wisc.edu // Get properties 32710447Snilay@cs.wisc.edu unsigned int number_rings = getGenProperties()->get("OutBits"); 32810447Snilay@cs.wisc.edu 32910447Snilay@cs.wisc.edu // Get tech model parameters 33010447Snilay@cs.wisc.edu double R = getTechModel()->get("Ring->Radius"); 33110447Snilay@cs.wisc.edu double n_g = getTechModel()->get("Ring->GroupIndex"); 33210447Snilay@cs.wisc.edu // This can actually be derived if we know thermo-optic coefficient (delta n / delta T) 33310447Snilay@cs.wisc.edu double sigma_r_local = getTechModel()->get("Ring->LocalVariationSigma"); 33410447Snilay@cs.wisc.edu 33510447Snilay@cs.wisc.edu // Get constants 33610447Snilay@cs.wisc.edu double c = Constants::c; 33710447Snilay@cs.wisc.edu double pi = Constants::pi; 33810447Snilay@cs.wisc.edu 33910447Snilay@cs.wisc.edu // Calculates the degree of bit re-order multiplexing needed for bit-reshuffling backend 34010447Snilay@cs.wisc.edu // Bit reshuffling tuning is largely unaffected by sigma_r_systematic. However, sigma_r_local 34110447Snilay@cs.wisc.edu // Can potentially throw each ring to a channel several channels away. This just calculates 34210447Snilay@cs.wisc.edu // the degree of bit reorder muxing needed to realign bits in the correct order 34310447Snilay@cs.wisc.edu 34410447Snilay@cs.wisc.edu // Setup calculations 34510447Snilay@cs.wisc.edu double L = 2 * pi * R; // Optical length 34610447Snilay@cs.wisc.edu double FSR = c / (n_g * L); // Free spectral range 34710447Snilay@cs.wisc.edu double freq_sep = FSR / number_rings; // Channel separation 34810447Snilay@cs.wisc.edu // Using 4 sigmas as the worst re-ordering case (must double to get both sides) 34910447Snilay@cs.wisc.edu unsigned int worst_case_channels = (unsigned int)ceil(2.0 * 4.0 * sigma_r_local / freq_sep); 35010447Snilay@cs.wisc.edu 35110447Snilay@cs.wisc.edu return worst_case_channels; 35210447Snilay@cs.wisc.edu } 35310447Snilay@cs.wisc.edu 35410447Snilay@cs.wisc.edu} // namespace DSENT 35510447Snilay@cs.wisc.edu 356