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-- costasloop.vhd
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
entity costasloop is
port(carrier: in signed(11 downto 0);
clk, reset: in std_logic;
op: out std_logic);
end costasloop;
architecture costasloop_arch of costasloop is
component nco is
port(clk, reset: in std_logic;
fword: in unsigned(5 downto 0);
op_sin: out signed(4 downto 0);
op_cos: out signed(4 downto 0));
end component;
component q_one_dot_fp_multiplier is
generic (a_word_size, b_word_size:integer);
port(a: in signed(a_word_size-1 downto 0);
b: in signed(b_word_size-1 downto 0);
mult_out: out signed(a_word_size + b_word_size -2 downto 0));
end component;
component lpf is
port(clk, reset: in std_logic;
x_in: in signed(15 downto 0);
y_out: out signed(19 downto 0));
end component;
component loopfilter is
port(clk, reset: in std_logic;
mult_error_op:in signed(38 downto 0);
f_desired: in unsigned(5 downto 0);
f_word_output: out unsigned(5 downto 0));
end component;
signal nco_input: unsigned(5 downto 0);
signal nco_sin, nco_cos: signed(4 downto 0);
signal mult_sin, mult_cos: signed(15 downto 0);
signal raw_op_sin, raw_op_cos: signed(19 downto 0);
signal mult_error_op: signed(38 downto 0);
begin
--NCO phase multiplier
N: nco port map(clk, reset, nco_input, nco_sin, nco_cos);
--Multiplier
M0: q_one_dot_fp_multiplier generic map(a_word_size=>nco_sin'length, b_word_size => carrier'length) port map(nco_sin, carrier, mult_sin);
M1: q_one_dot_fp_multiplier generic map(a_word_size=>nco_sin'length, b_word_size => carrier'length) port map(nco_cos, carrier, mult_cos);
--FIR Filter
L0: lpf port map(clk, reset, mult_sin, raw_op_sin);
L1: lpf port map(clk, reset, mult_cos, raw_op_cos);
--Extract output (Comparator)
COMPARATOR: op <= raw_op_sin(raw_op_sin'length -1); --Sign bit
--Error Multiplier
EM: q_one_dot_fp_multiplier generic map(a_word_size=>raw_op_sin'length, b_word_size => raw_op_cos'length) port map(raw_op_sin, raw_op_cos, mult_error_op);
--Loop Filter
--NCO mapping to error
LF: loopfilter port map(clk, reset, mult_error_op, to_unsigned(16, 6), nco_input);
end costasloop_arch;
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