Reconstruction of Sinusoidal Signal

Fahim
2012-11-29
2013-06-12
  • Fahim
    Fahim
    2012-11-29

    Hi,

    I am trying to implement NgSpice netlist in which I am converting sinusoidal into digital form using adc and after some processing signal I want to convert the digital signal in sinusoidal form to give feedback to my input signal.

    But the problem is when I am using dac to convert digital into analog I am getting only square wave only.
    My question is how can I sample the sinusoidal signal in NgSpice and using dac how can I get the signal in sinusoidal form again.
    Any initiative help is appreciated
    Thanks!!!!

    Regards,
    Fahim

     
  • Fahim
    Fahim
    2012-12-03

    Hi Holger,

    I am trying to implement sigma-delta modulator with below netlist.  For time being I am not considering counter.

    Please find the netlist below.

    ****Integrator using  VCVS
    .tran 1e-6 1.5e-3
    *.ic v(vo1)=0
    vin in 0 SIN(0 1 10k)
    Vreset areset 0 PWL(0ms 0.0 0.1ms 0.0 0.15ms 2.0 1.5ms 2.0)
    Vset aset 0 PWL(0ms 0.0 0.1ms 0.0 0.15ms 2.0 1.5ms 2.0)
    Vclk aclk 0 PULSE(0 1 0ms 0ms 0ms 0.05ms 0.1ms)
    ro in vi1 10K
    co vi1 vo1 1nF
    r1 vi1 vo1 100k
    *E1 vo1 0 vi1 0 1e6
    E1 0 vo1 0 vi1 300e6
    adc1 [aclk] [dclk] adc
    adc2 [areset] [dreset] adc
    adc3 [aset] [dset] adc
    aadc [vo1] [dout] adc
    adff dout dclk dset dreset qout nqout dff
    adac [qout] [aout] dac
    *E2 in aout vi1 0 1
    a1 %v[in aout] vi1 sum
    ***Model****
    .model dff d_dff(clk_delay = 13.0e-9 set_delay = 25.0e-9 reset_delay = 27.0e-9 ic = 2 rise_delay = 10.0e-9
    .model adc adc_bridge ( in_low =0.0 in_high =1.0 rise_delay =1.0e-10 fall_delay =1.0e-10)
    .model dac dac_bridge(out_low = -5.0 out_high = 5.0 out_undef = 1.0
    +                      input_load = 5.0e-14 t_rise = 1.0e-10
    +                      t_fall = 1.0e-10)
    .model sum summer(out_gain = 1)
    .end
    

    I just want to get sinusoidal output at dac and to give as feedback to my input.

    Can you just enlighten me how can I reconstruct sinosoidal output.?
    What changes should I made with ADC and DAC?

    Thanks
    Regards,
    Fahim Khan

     
  • Fahim
    Fahim
    2012-12-03

    Hi,

    I am using voltage controlled voltage source to implement integrator as

    E1 0 vo1 0 vi1 300e6

    Is it correct way to use?

    Regards,
    Fahim

     
  • Holger Vogt
    Holger Vogt
    2012-12-03

    Fahim,

    unfortunately I have no time resources to support your design work.

    Of course I am open to questions concerning ngspice use.

    Holger

     
  • Fahim
    Fahim
    2012-12-03

    Hi Holger,

    Can you let me know what should I use for adding two signal like if I want to add input signal with -ve feedback signal.

    Thanks