\documentclass[convert,tikz]{standalone}
\usepackage[spanish]{babel}
\usepgflibrary{arrows.meta} % Uso de biblioteca de flechas
\usetikzlibrary{shapes} % Biblioteca de formas

% Definición de bloques
\tikzstyle{block1} = [draw, very thick, rectangle, minimum height=2cm, minimum width=3cm]
\tikzstyle{block2} = [draw, very thick, rectangle, minimum height=1cm, minimum width=1cm]
\tikzstyle{amp} = [draw, very thick, isosceles triangle, shape border uses incircle]
\tikzstyle{mix} = [draw, very thick, circle, minimum size=1cm]
% Definición de estilos
\tikzstyle{ann} = [font=\large \bf ,inner sep=1pt, align=center] % Estilo de nodo
\newcommand{\inte}{$\displaystyle \int$} % Signo de integral en gran tamaño
\newcommand{\pit}{\Large $ -\frac{\pi}{2}$} % Signo de pi/2 en gran tamaño
\newcommand{\mixe}{\Huge $\times$} % Signo de "X" en gran tamaño
\newcommand{\suma}{\Huge $+$} % Signo de "+" en gran tamaño
\begin{document}
\begin{tikzpicture}[very thick,-Stealth]
% Diagrama de un Modulador GSMK
	% \draw [cyan, thin, dashed, step=0.5] (-1,1) grid (17,-9);
	% Modulador tipo VCO
	\node [ann] at (1,0){Datos};
	\node [ann, block1] at(5,0)(fpbg1){Filtro pasabajo \\gaussiano};
	\node [ann, block1,font=\Huge] at(10,0)(vco){VCO};
	\node [ann, amp] at(14,0)(amp1){Amp.\\RF};
	\draw (2,0)--(fpbg1);
	\draw (fpbg1)--(vco);
	\draw (vco)--(amp1);
	\draw (amp1)--++(4.5,0) node[ann,right=15]{Salida \\GMSK};
	% Modulador en cuadratura (IQ)
	\node [ann] at (-1,-6){Datos};
	\node [ann, block1] at(3,-6)(fpbg2){Filtro pasabajo \\gaussiano};
	\node [ann, font=\Large, block2] at(7,-6)(intg){\inte dt};
	\draw (fpbg2)--(intg);
	\node [ann, block2] at(10.5,-9)(del1){\pit};
	\node [ann, block2] at(12.5,-7)(del2){\pit};
	\node [ann, mix] at(10.5,-5)(port){$f_C$};
	\draw (0,-6)--(fpbg2);
	\node [ann,mix] at(12.5,-3)(mix1){\mixe};
	\node [ann,mix] at(12.5,-9)(mix2){\mixe};
	\draw (intg) --++(2,0) |-(mix1.west);
	\draw (intg) --++(2,0) |-(del1.west);
	\draw (del1) -- (mix2);
	\draw (del2.south) -- (mix2.north);
	\draw (port.east)-|(del2.north);
	\draw (port.east)-|(mix1.south);
	\node [ann,mix] at(16,-6)(add){\suma};
	\draw (mix1.east) -| (add.north);
	\draw (mix2.east) -| (add.south);
	\draw (add.east) -- ++(2,0)node[ann,right=15]{Salida \\GMSK};
\end{tikzpicture}
\end{document}