用于高线性单端转差分的恒定跨导运算放大器  

Constant transconductance operational amplifier for high-linearity single-ended to differential

作　　者：佟星元 党磊 TONG Xingyuan;DANG Lei(School of Electronics Engineering,Xi’an University of Posts and Telecommunications,Xi’an 710121,China)

机构地区：[1]西安邮电大学电子工程学院,陕西西安710121

出　　处：《西安邮电大学学报》2025年第2期40-47,共8页Journal of Xi’an University of Posts and Telecommunications

基　　金：国家自然科学青年基金项目(62271389)。

摘　　要：单端输入转差分输出电路通常以全差分运放为核心,构建反相比例放大器并将其中一个输入端接共模电平实现单端输入,要求全差分运放在全输入范围具有稳定的跨导以保障在宽输入应用具有高线性度。针对现有3倍电流镜全差分运放跨导稳定性优化技术效果不佳问题,提出了一种输入级分段尾电流补偿技术,在输入对管跨导变弱的截止区和亚阈值区内自适应地提供不同的补偿电流,提高跨导稳定性优化效果。基于0.18μm CMOS工艺设计了全差分运放,面积为0.051 mm^(2)。在1.8 V全输入范围跨导仅变化0.95%。将设计的全差分运放用于单端转差分电路进行验证,当负载电容为10 pF,信号频率为1 MHz时,实现了-94.3 dB的总谐波抑制效果。与其他全差分运放相比,所提设计实现了较好的线性度。A single-ended input to differential output circuit typically uses a fully differential operational amplifier(op-amp)as the core to construct an inverting proportional amplifier,where one input is connected to a common-mode voltage level to implement the single-ended input.The fully differential op-amp is required to maintain a stable transconductance across the full input range to ensure high linearity in wide-input applications.To address the issue of insufficient transconductance stability optimization in the existing triple-current-mirror fully differential op-amps,an input-stage piecewise tail current compensation technique is proposed.It adaptively provides different compensation currents in the cutoff and sub-threshold regions of the input pair transconductance,enhancing the stability optimization of the transconductance.A fully differential op-amp is designed using a 0.18μm CMOS process with an area of 0.051 mm^(2).The transconductance variation over the full input range at 1.8 V is only 0.95%.The designed fully differential op-amp is used in a single-ended to differential circuit for validation.When the load capacitance is 10 pF and the signal frequency is 1 MHz,a total harmonic distortion(THD)suppression of-94.3 dB is achieved.Compared with other fully differential op-amps,the proposed design demonstrates better linearity.

关 键 词：单端转差分 高线性 全差分运放 恒定跨导 电流补偿 

分 类 号：TN432[电子电信—微电子学与固体电子学]