Device Models

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Spice Models

Matlab Models

Download a set of matlab (�) models that capture the basic equations for transistors and inverters, as introduced in the textbook. The model archive (6 kB) contains the following functions:

Transistor static models

  • mos(W, L, vgs, vds, vsb, technology): captures the unified DSM MOS model as introduced in the text
    technology is a vector with 8 elements 
    [type vt0 gamma beta lambda vdsat ld wd] (type is 1 for NMOS, -1 for PMOS)
  • threshold(vsb, type, vt0, gamma): computes the actual threshold of the transistor as a function of the body bias
  • nmos025(W, L, vgs, vds, vsb) and pmos025(W, L, vgs, vds, vsb): compute the MOS model for the 0.25 micron CMOS technology used in the text
  • nmos025id and pmos025id: plots the id(vds) curves for the 0.25 micron transistors. A 2.5 V range of voltages is assumed.
  • nmos025vgs: generate the id(vgs) curves for the 0.25 micron transistors. A 2.5 V range of voltages is assumed.

Transistor capacitive models

  • gatecap(W,L,ctech, region): computes the gate cap and its distribution dependent upon the operation regaion. region is the operational region of the transistor (cutoff=0, linear=1 or sat=2). ctech is an 8 element vector containing the essential technology parameters needed to compute the capacitances: [tox, cov, cj, mj, pb, cjsw, mjsw, pbsw]
  • junctioncap(vb, cj0, m, phi): computes the junction cap as a function of the bias voltage
  • moscap(W, L, vgs, vds, vsb, tech, ctech): generates a vector containing the 5 transistor capacitances
    [cgs cgd cgb cdb csb].  tech and ctech are the transistor and capacitance technology vectors respectively. 
  • nmos025cap(W, L, vgs, vds, vsb) and pmos025cap(W, L, vgs, vds, vsb): compute the capacitances of 0.25 micron NMOS and PMOS transistors
  • keq(vb, m, phi): computes the linearizing keq factor as a function of the voltage range

Inverter models

  • inverter_vtc(vdd, wn, ln, wp, lp): Plots the voltage transfer characteristic of an inverter as a function of supply voltage and transistor dimensions. WARNING: This functions takes some compute time!
  • inverter_threshold(vdd, wn, ln, wp, lp): computes the inverter threshold as a function of the transistor dimensions
  • inverter_gain(vdd, wn, ln, wp, lp): computes the gain at VM. It returns two values, one obtained from the simple equation in the book, the second one taking the channel-length modulation into account.