NMOS verilog-a
时间: 2023-10-11 10:07:29 浏览: 84
NMOS (N-channel Metal-Oxide-Semiconductor) is a type of transistor used in digital and analog circuits. Verilog-A is a hardware description language used to model and simulate analog circuits. Here is an example of an NMOS Verilog-A model:
`module nmos_va (in, out, g, s, b, l, w, ad, pd, as, ps, ab, pb, ag, pg, vdd, vss, temp)`
`// Inputs`
`input in; // Input signal`
`input g; // Gate signal`
`// Outputs`
`output out; // Output signal`
`// Nodes`
`analog s, b; // Source and bulk nodes`
`analog l, w; // Length and width parameters`
`analog ad, pd; // Drain and bulk area factors`
`analog as, ps; // Source and bulk area factors`
`analog ab, pb; // Body effect factors`
`analog ag, pg; // Gate effect factors`
`// Power supply and temperature`
`analog vdd, vss, temp;`
`// Model parameters`
`parameter real k = 0.001; // Transconductance factor`
`parameter real vth0 = 0.7; // Threshold voltage at 0K`
`parameter real phi = 0.8; // Surface potential`
`parameter real ld = 0.05; // Channel length modulation factor`
`parameter real rd = 0.1; // Drain resistance`
`parameter real rs = 0.05; // Source resistance`
`parameter real cgs = 1e-12; // Gate-source capacitance`
`parameter real cgd = 1e-12; // Gate-drain capacitance`
`// Equations`
`analog vgs, vds, vbs, vth, ids, gm, gds, gmb;`
`vgs = g - s;`
`vds = d - s;`
`vbs = b - s;`
`vth = vth0 + phi * (sqrt(abs(vbs)) - sqrt(abs(vbs) - 2 * phi));`
`ids = k * l / w * (vgs - vth) * (1 + ld * vds) * (1 + as * ad * vds) * (1 + pb * vbs) * (1 + pg * vgs);`
`gm = k * l / w * (1 + ld * vds) * (1 + as * ad * vds) * (1 + pb * vbs) * (1 + pg * vgs);`
`gds = k * l / w * ld * (vgs - vth) * (1 + as * ad * vds) * (1 + pb * vbs) * (1 + pg * vgs);`
`gmb = k * l / w * (1 + ld * vds) * (1 + as * ad * vds) * pb * (1 + pg * vgs);`
`out = ids * rd;`
`// Capacitances`
`analog cgs, cgd;`
`cgs = cgs * l * w;`
`cgd = cgd * l * w;`
`// Current sources`
`analog ig, id, is;`
`ig = 0;`
`id = -ids;`
`is = ids;`
`// Model statement`
`analog_model nmos_va_model (ig, id, is, vgs, vds, vbs, vth, gm, gds, gmb, cgs, cgd, vdd, vss, temp);`
`endmodule`
This model includes inputs for the input and gate signals, outputs for the output signal, and nodes for the source, bulk, length, width, and various other parameters. Equations are used to calculate the output current based on the input and gate voltages, and capacitances and current sources are also included. The model statement at the end defines the NMOS Verilog-A model.