classdef CTLE < handle

    properties(Access=public)
        Aac_dB
        Adc_dB
        f_p1
        f_p2
        plot
    end

    methods(Access=public)
        function obj = CTLE(options)
            arguments
                options.Aac_dB = 0;
                options.Adc_dB = -6;
                options.f_p1 = 1.5e9;
                options.f_p2 = 5e9;
                options.plot = 0;
            end

            fn = fieldnames(options);
            for n = 1:numel(fn)
                obj.(fn{n}) = options.(fn{n});
            end

        end

        function data_out = process(obj, data_in)

            x  = data_in.signal(:);
            Fs = data_in.fs;
            N  = length(x);

            % CTLE Transfer Function Parameters
            A_ac = 10^(obj.Aac_dB/20);
            A_dc = 10^(obj.Adc_dB/20);
            w1   = 2*pi*obj.f_p1;
            w2   = 2*pi*obj.f_p2;

            % Frequency Domain Conversion
            X = fft(x);

            % Generating Frequency Axis In The Range Of [-Fs/2,Fs/2]
            f_fft = (0:N-1).' * (Fs/N);
            f_signed = f_fft;
            idxNeg = f_signed > Fs/2;
            f_signed(idxNeg) = f_signed(idxNeg) - Fs;
            f_pos = abs(f_signed);
            w_pos = 2*pi*f_pos;
            s_pos = 1j*w_pos;

            % Calculate CTLE Transfer Function
            H_pos = A_ac*w2 .* (s_pos + (A_dc/A_ac)*w1) ./ ((s_pos + w1).*(s_pos + w2));

            % Enforce H(-f) = conj(H(f)) For Negative Bins
            H = H_pos;
            H(idxNeg) = conj(H_pos(idxNeg));

            % Apply CTLE
            Y = H .* X;

            % Calculate Time Domain Signal
            y = ifft(Y, 'symmetric');
            data_out = data_in;
            data_out.signal = y;
            data_out.fs = Fs;

            % Plot
            if obj.plot
                % plot only positive frequencies up to Fs/2
                k = 1:floor(N/2)+1;
                fplot = f_fft(k);
                Hplot = H(k);

                figure;
                semilogx(fplot, 20*log10(abs(Hplot)+1e-15));
                grid on; xlabel('frequency (Hz)'); ylabel('magnitude (dB)');
                title('CTLE magnitude on FFT grid');
            end
        end
    end
end