Voltage-controlled oscillator model (VCO)

This article contains two models:

Model 1: Gain (V/Hz) is set directly

Model 2: Gain (V/Hz) is set through start/stop frequency

Tunable parameters:

• [1] Gain (in V/Hz) [2] Start/Stop frequency;
• DC offset;
• Amplitude;
• Start frequency;
• Number of points per period - can be useful for FFT simulations etc.

1// VCO model
2// Contains two models:
3// Model 1: Gain (V/Hz) is set directly
4// Model 2: Gain (V/Hz) is set through start/stop frequency
5// Author: A. Sidun
6// Source: AnalogHub.ie
7
8`include "constants.vams"
9`include "disciplines.vams"
10
11// Model 1: Gain (V/Hz) is set directly
12module vco(out,in); 
13voltage out,in; 
14parameter real Gain_Hz_per_V = 1e6; 
15parameter real DC_offset = 1;
16parameter real Amplitude = 1;
17parameter real Points_per_period = 100;
18parameter real Start_freq = 1e6;
19real phase, freq; 
20 
21	analog begin 
22		freq = Start_freq+Gain_Hz_per_V*V(in); 
23		phase = idtmod(freq,0,1); 
24		V(out) <+ DC_offset+Amplitude*cos(2*`M_PI*phase); 
25		$bound_step(1/(Points_per_period*freq)); 
26	end 
27endmodule 
28
29// Model 2: Gain (V/Hz) is set through start/stop frequency
30module vco(out,in); 
31voltage out,in; 
32parameter real DC_offset = 1;
33parameter real Amplitude = 1;
34parameter real Points_per_period = 100;
35parameter real Start_frequency = 1e6;
36parameter real Stop_frequency = 10e6;
37real phase, freq, gain; 
38 
39	analog begin 
40		gain = Stop_frequency/Start_frequency;
41		freq = Start_frequency+gain*V(in); 
42		phase = idtmod(freq,0,1); 
43		V(out) <+ DC_offset+Amplitude*cos(2*`M_PI*phase); 
44		$bound_step(1/(Points_per_period*freq)); 
45	end 
46endmodule