A logic element designed to act as either an adder or a subtracter in accordance with the control signal applied to it.
根据供给它的控制信号，或起加法器作用或起减法器作用的一种逻辑元件。
2
The subtracter (230) calculates the difference between the output of the adder (250) and the quantized value of the output of the adder (250) to determine the quantization error.