Resistor Ladder DA Converter on 4 bit

Left first switch is the MSB (most significant bit) ABCD / U 0000 = 0V 0001 = -1V 0010 = -2V 0011 = -3V 0100 = -4V 0101 = -5V 0110 = -6V 0111 = -7V 1000 = -8V 1001 = -9V 1010 = -10V 1011 = -11V 1100 = -12V 1101 = -13V 1110 = -14V 1111 = -15V