提供FPGA产生调频信号的代码

以下是一个使用FPGA产生调频信号的VHDL代码示例：

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;

entity fm_modulator is
    Port ( clk : in  STD_LOGIC;
           reset : in  STD_LOGIC;
           modulating_signal : in  STD_LOGIC_VECTOR (15 downto 0);
           carrier_frequency : in  STD_LOGIC_VECTOR (15 downto 0);
           fm_output : out  STD_LOGIC);
end fm_modulator;

architecture Behavioral of fm_modulator is

    signal phase_accumulator : unsigned(31 downto 0) := (others => '0');
    signal phase_increment : unsigned(31 downto 0) := (others => '0');
    signal modulating_signal_scaled : unsigned(31 downto 0) := (others => '0');
    signal carrier_frequency_scaled : unsigned(31 downto 0) := (others => '0');

begin

    modulating_signal_scaled <= resize(unsigned(modulating_signal), 32);
    carrier_frequency_scaled <= resize(unsigned(carrier_frequency), 32);

    phase_increment <= resize(carrier_frequency_scaled + resize(modulating_signal_scaled * 100), 32);

    process (clk, reset)
    begin
        if (reset = '1') then
            phase_accumulator <= (others => '0');
            fm_output <= '0';
        elsif (rising_edge(clk)) then
            phase_accumulator <= phase_accumulator + phase_increment;
            fm_output <= std_logic(shift_right(phase_accumulator, 23));
        end if;
    end process;

end Behavioral;

这个代码实现了一个简单的调频调制器，输入调制信号和载波频率，输出FM调制信号。代码中使用了一个相位累加器和相位增量器来生成调制信号的相位，然后通过移位操作将相位转换成模拟输出信号。请注意，这只是一个简单的示例，您可能需要根据自己的需求进行修改和优化。