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Jeferson

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  1. Hi maehne, thank you very much for the answers. 1) Yes, my time step is set in srcs (Tm_ = 1e-9) and the expected cut-off frequency is approximately 2MHz. 2) I was able to find the expected cutoff frequency with good accuracy, even with the TDF-> DE domain conversion ports, but I will change to achieve better results as you indicated !! The error was in my analysis, because the input sinusoid had an off set DC which changes the shape to find the cutoff frequency, but I have already solved it. 3) Yes I will follow the instructions to use the recommended headers.
  2. Hello everyone, I'm performing the verification of a simple Sample and Hold implemented in SystemC-AMS. The Sample and Hold is modeled with the MOC ELN, the MOC TDF input signal source, and Sample and Hold output a port for the discrete domain. When the sample switch is closed for a long time the circuit has a low pass filter behavior, so the check consists of finding the cut-off frequency in this situation through the voltage gain (v_out / v_in = 0.707). However, this gain is only being achieved with frequencies much larger than the cutoff frequency. Codes are shown below Can anyone help? The V_in and Vout measurements are made by the read () method on the input signal "sc_core :: sc_signal <double> adc_in_source" and "sc_core :: sc_signal <double> adc_out". Thank you in advance. #include <systemc-ams.h> #include <cmath> class sample : public sc_module { public: sca_tdf::sca_in < bool > ctrl_lp; // CAPCOM input for the switch sc_in < double > in_src; // Analog signal input from the MUX sc_out < double > out; // Sampled signal output sca_eln::sca_tdf_rswitch key; // Switch ideal. Simulates sample switching. sca_eln::sca_node n1,n2,n3,n4; // electrical nodes sca_eln::sca_node_ref gnd; sca_eln::sca_c CI; // Low-pass filter input capacitance sca_eln::sca_r RI; // Internal filter resistance low pass filter sca_eln::sca_r RS; // External source resistance sca_eln::sca_de::sca_vsource vin_src; sca_eln::sca_de::sca_vsink vout; sample(sc_module_name name) : sc_module(name) , CI("CI") , RI("RI") , vin_src("vin_src") , vout("vout") , RS ("RS") , key("key") { vin_src.inp(in_src); vin_src.p(n1); vin_src.n(gnd); RS.value = 0e3; RS.n(n1); RS.p(n2); RI.value = 2e3; RI.n(n2); RI.p(n3); key.p(n4); key.n(n3); key.ctrl(ctrl_lp); key.ron; key.roff; CI.value = 40e-12; CI.q0 = 0.0; CI.p(n4); CI.n(gnd); vout.outp(out); vout.p(n4); // Vout.tdf_voltage(out); vout.n(gnd); } ~sample(){} }; #ifndef SRCS_H #define SRCS_H # include <systemc-ams.h> SCA_TDF_MODULE (srcs) { sca_tdf::sc_out<double> out_tdf_de; // output port srcs( sc_core::sc_module_name nm, double ampl_, double freq_, sca_core::sca_time Tm_) : out_tdf_de ("out_tdf_de") , ampl(ampl_) , freq_1(freq_) , Tm(Tm_) {} void set_attributes(); void processing(); public: double t; double ampl; // amplitude double freq_1; // frequency double data;// setup_param; int setup; sca_core::sca_time Tm; // module time step }; #endif // srcs_H #include "srcs.h" #include <cstdlib> /// for std::rand #include <cmath> void srcs::set_attributes() { set_timestep(Tm); } void srcs::processing(){ t = out_tdf_de.get_time().to_seconds(); // Get current time of the sample data = (ampl/2)*sin((2.0 * M_PI * freq_1 * t)) + ((ampl/2)); out_tdf_de.write(data); // Write value on output }
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