project2.m

%% Project design script
clc; clear;
%%%%%%%%%%%%%%%%%%%%%%%% Specifications %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Vdd = 2.5; % in volts
Vss = -2.5; % in Volts
Rout = 5e3; % in ohms (really 1/2 Rout)
Cin = 100e-15; % in fF
f3dB_target = 65e6; %in Hz
P_totl = 1.35e-3; %in Watts
IDtot = P_totl / (Vdd - Vss);
Tau_total = 1/(2*pi) * 1/f3dB_target; % in seconds
Cout = 1000e-15; %F really this is 2*Cout which is required for 1/2 circuit
Rm = 20e3; % 20k transresistance small signal

%%%%%%%%%%%%%%%%%%%% Technology Parameters %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Lmin = 1e-6;    % m
Cox = 2.3e-3;   % F/m^2
kp_n = 50e-6;   % A/V^2
kp_p = 25e-6;   % A/V^2

%%%%%%%%%%%%%%%%%%%% Simplifying assumptions %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Csb_Cgs = 0.33;
Cdb_Cgs = 0.33;
Cgd_Cgs = 0.25;
%%%%%%%%%%%%%%%%%%%% Design Choices %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%How much tau we give to each stage of the circuit
%Tau = Tau_total*[0.25 0.25 0.25 0.25];

% x1 = Cgs1/Cin
% x2 = Cgs2/Cgs1
% x3 = Cgs3/Cout
% x = [1 1 1];

L1 = 1e-6;
L2 = 1e-6;
L3 = 1e-6;
LL1 = 1e-6;
LL2 = 1e-6;

% Vov1 = 0.3;
% Vov2 = 0.3;
% Vov3 = 0.3;
% VovL1 = 0.3;
% VovL2 = 0.3;

%%%%%%%%%%%%%% Optimization Parameters %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%ID1_IDtot = 0.3;    % fraction of total current in branch 1
%ID2_IDtot = 0.4;    % fraction of total current in branch 2
%Av1 = 1000;           % Gain of 1st stage

%%%%%%%%%%%%%%%%%%%%%%%%% Dependent Params %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%Av2 = Rm / .8 / Av1;% Gain of 2nd stage

feasible_ID = [];
feasible_W = [];
feasible_gain = [];
feasible_BW = [];
feasible_Vov = [];
feasible_gm = [];
gbp = [];
minW = 1e-6*[2 2 2 2 2 2 2 2];

ID1_IDtot = linspace(.001, .5, 20);
ID2_IDtot = linspace(.001, .5, 20);
VovBias1 = 1;
VovBias2 = 1;
VovBias3 = 1;
Vov1Vec = linspace(0.15,1.5,12);
Vov2Vec = linspace(0.15,1,10);
Vov3Vec = linspace(0.15,1,10);
VovL1Vec = linspace(0.15,1.5,12);
VovL2Vec = linspace(0.15,1.5,12);

for k=1:length(Vov1Vec)
    Vov1 = Vov1Vec(k);
    for l=1:length(Vov2Vec)
        Vov2 = Vov2Vec(l);
        for m=1:length(Vov3Vec)
            Vov3 = Vov3Vec(m);
            for n=1:length(VovL1Vec)
                VovL1 = VovL1Vec(n);
                for o=1:length(VovL2Vec)
                    VovL2 = VovL2Vec(o);
                    for i = 1 : length(ID1_IDtot)
                        ID1 = ID1_IDtot(i) * IDtot;
                        for j = 1 : length(ID2_IDtot)
                            ID2 = ID2_IDtot(j) * IDtot;
                            ID3 = (1 - ID1_IDtot(i) - ID2_IDtot(j)) * IDtot;
                            
                            if ID1_IDtot(i) + ID2_IDtot(j) > 1
                                break;
                            end
                            
                            %%%% Calculations for Tau1
                            % M1
                            gm1 = 2*ID1/Vov1;
                            w1 = (2*ID1*L1) / (kp_n*Vov1^2);
                            Cgs1 = 2/3*w1*L1*Cox;
                            Csb1 = Cgs1*Csb_Cgs;
                            Cgd1 = Cgs1*Cgd_Cgs;
                            Cdb1 = Cgs1*Cdb_Cgs;
                            
                            tau1 = (1/gm1)*(Cgs1+Cin+Csb1); %Both ZVTC and Miller
                            
                            %%% Calculations for Tau2
                            % ML1
                            gmL1 = 2*ID1/VovL1;
                            %        gmL1 = Av1 * ID1 / (Av1 * Vdd - 2 * ID1);
                            wL1 = (2*ID1*LL1) / (kp_p*VovL1^2);
                            CgsL1 = 2/3*wL1*LL1*Cox;
                            CdbL1 = CgsL1*Cdb_Cgs;
                            
                            %        VovL2 = Vov2 * gmL1 * (Vdd - 1/gmL1 * ID1 * Av2) / ID1
                            
                            %ML2
                            gmL2  = 2*ID2/VovL2;
                            wL2   = (2*ID2*LL2) / (kp_p*VovL2^2);
                            CgsL2 = 2/3*wL2*LL2*Cox;
                            CdbL2 = CgsL2*Cdb_Cgs;
                            
                            % M2
                            gm2 = 2*ID2/Vov2;
                            w2 = (2*ID2*L2) / (kp_n*Vov2^2);
                            Cgs2 = 2/3*w2*L2*Cox;
                            Csb2 = Cgs2*Csb_Cgs;
                            Cgd2 = Cgs2*Cgd_Cgs;
                            Cdb2 = Cgs2*Cdb_Cgs;
                            
                            %tau2 = (1/gmL1)*(Cgd1+Cdb1+CgsL1+Cgs2+CdbL1+Cgd2 + (gm2/gmL2)*Cgd2); % ZVTC
                            tau2 = (1/gmL1)*(Cgd1+Cdb1+CgsL1+Cgs2+CdbL1 + Cgd2+ (gm2/gmL2)*Cgd2);
                            %tau2 = (1/gmL1)*(Cgd1+Cdb1+CgsL1+Cgs2+CdbL1 + (1+gm2/gmL2)*Cgd2); %MIller
                            
                            %%% Calculations for Tau3
                            
                            % M3
                            gm3  = 2*ID3/Vov3;
                            w3   = (2*ID3*L3) / (kp_n*Vov3^2);
                            Cgs3 = 2/3*w3*L3*Cox;
                            Csb3 = Cgs3*Csb_Cgs;
                            Cgd3 = Cgs3*Cgd_Cgs;
                            Cdb3 = Cgs3*Cdb_Cgs;
                            gmb3 = gm3*0.2;
                            gm3prime = gm3+gmb3;
                            
                            tau3 = (1/gmL2) * (Cgd2+Cgd3+Cdb2+CgsL2+CdbL2 + (1/(1+(gm3/gmb3)))*Cgs3); %ZVTC 
                            %tau3 = (1/gmL2) * (Cgd3+Cdb2+CgsL2+CdbL2+(1-0.8)*Cgs3); % Miller
                            
                            % Calculations for tau4
                            
                            tau4 = (Rout / (Rout * gm3prime + 1)) * (Cout+Csb3+Cgs3); %ZVTC
                            %tau4 = (Rout / (Rout * gm3prime + 1)) * (Cout+Csb3); %Miller
                            %tau4 = (1/gm3prime) * (Cout+Csb3+Cgs3); %ZVTC
                            
                            tau = [tau1 tau2 tau3 tau4];
                            
                            f3dB = 1/(2*pi) * 1/sum(tau);
                            %gain = 1/gmL1 * gm2 / gmL2 * 0.8
                            
                            Av1 = 1/gmL1;
                            Av2 = gm2/gmL2;
                            Av3 = gm3/(gm3prime);
                            
                            gain = Av1*Av2*Av3;
                            
                            %if(ID3>270e-6)
                                %disp('ID3 greater than 270');
                            %end
                            
                            %bias gm's. We set their overvoltage to 1
                            gm1bias = 2*ID1/1;
                            gm2bias = 2*ID2/1;
                            gm3bias = 2*ID3/1;
                            
                            wbias1 = 2*ID1*Lmin/(kp_n*(VovBias1^2));
                            wbias2 = 2*ID2*Lmin/(kp_n*(VovBias2^2));
                            wbias3 = 2*ID3*Lmin/(kp_n*(VovBias3^2));
                            VovVec = [Vov1 Vov2 Vov3 VovL1 VovL2];
                            IDVec = [ID1 ID2 ID3];
                            Wvec = [w1 w2 w3 wL1 wL2 wbias1 wbias2 wbias3];
                            gmVec = [gm1 gm2 gm3 gmL1 gmL2 gm1bias gm2bias gm3bias];
                            if(f3dB > f3dB_target && sum(Wvec > minW) == 8 && gain >= Rm)
                                disp('feasible point found');
                                feasible_ID = [feasible_ID ; IDVec];
                                %disp(['i=' num2str(i) ' ' num2str(ID1_IDtot(i)) ' ' num2str(ID1)]);
                                %disp(['j=' num2str(j) ' ' num2str(ID2_IDtot(j)) ' ' num2str(ID2)]);
                                feasible_W = [feasible_W; Wvec];
                                feasible_BW = [feasible_BW f3dB];
                                feasible_gain = [feasible_gain gain];
                                feasible_Vov = [feasible_Vov; VovVec];
                                feasible_gm = [feasible_gm; gmVec];
                                gbp = [gbp f3dB*gain];
                                disp(['Gain = ' num2str(gain)]);
                                disp(['BW = ' num2str(f3dB)]);
                                disp(['IDs are: ' num2str(IDVec) ]);
                                disp(['Ws are: ' num2str(Wvec) ]);
                      
                            end
                        end
                    end
                end
            end
        end
    end
end

[maxgbp mgbpidx] = max(gbp)


VovBias1 = 1;
VovBias2 = 1;
VovBias3 = 1;

Wbias1 = 2*ID1*Lmin/(kp_n*(VovBias1^2));
Wbias2 = 2*ID2*Lmin/(kp_n*(VovBias2^2));
Wbias3 = 2*ID3*Lmin/(kp_n*(VovBias3^2));