gistfile1.cs

// Scaled Radial Dead Zone
float deadzone = 0.25f;
Vector2 stickInput = new Vector2(Input.GetAxis("Horizontal"), Input.GetAxis("Vertical"));
float inputMagnitude = stickInput.magnitude;

if (inputMagnitude < deadzone)
{
    stickInput = Vector2.zero;
}
else
{
    // rescale the clipped input vector into the non-dead zone space
    stickInput *= (inputMagnitude - deadzone) / ((1f - deadzone) * inputMagnitude);
}