帮我把这句话用英文表达：由于每一级amplifier的传输函数都与输入电压有关攻击者无法使用单一变量拟合电路中单元的特性尽管实际工作中会多次复用这些单元因此极大提高了电路的建模复杂性

"Due to the fact that the transfer function of each amplifier is dependent on the input voltage, attackers are unable to fit the characteristics of individual units in the circuit with a single variable. Although these units may be reused multiple times in practical applications, this greatly increases the complexity of circuit modeling."