def CurrentAmplifierThreePortDenom(G, Zi, Zo):
    """symbolic three port current amplifier denominator
    @param G string current gain
    @param Zi string input impedance
    @param Zo string output impedance
    @return the denominator element common in the s-parameter matrix as a string
    containing LaTeX or ASCII strings for each element.
    @note strings can be any valid LaTeX
    @note this is the symbolic version of SignalIntegrity.Lib.Devices.CurrentAmplifier.CurrentAmplifierThreePort
    @see CurrentAmplifierThreePortWithoutDenom
    """
    D = ('3\\cdot Z0^2+ (2\\cdot ' + Zo + '+2\\cdot ' + Zi + '-' + G +
        '\\cdot ' + Zo + ' )\\cdot Z0+' + Zo + '\\cdot ' + Zi)
    return D
