一种适用于低电压模数转换器的新型采样开关(英文)

A Novel Sampling Switch Suitable for Low-Voltage Analog-to-Digital Converters

提出了一种适用于低电源电压的新型高线性度采样开关.与传统低电压采样开关相比,这种新型采样开关不仅消除了MOS开关由于栅源电压随输入信号变化所引入的非线性,而且进一步消除了MOS开关由于阈值电压随输入信号变化引入的非线性.这是通过采用一个与采样MOS开关具有相同阈值电压的“复制”开关得以实现的.基于Chartered 0·35μm标准CMOS工艺,文中设计了一个此类新型MOS采样开关,在输入信号为0·2MHz正弦波,峰峰值为1·2V,采样时钟频率为2MHz时,无杂散动态范围达到111dB,比栅压自举开关提高了18dB;同时导通电阻的变化减小了90%.这种新型采样开关特别适用于低电压,高精度模数转换器.

A novel, highly linear sampling switch suitable for low-voltage operation is proposed. This switch not only eliminates the nonlinearity introduced by gate-source voltage variation, but also reduces the nonlinearity resuiting from threshold voltage variation, which has not been accomplished in earlier low-voltage sampling switches. This is achieved by adopting a replica transistor with the same threshold voltage as the sampling transistor. The effectiveness of this technique is demonstrated by a prototype design of a sampling switch in 0. 35μm. The proposed sampling switch achieves a spurious free dynamic range of 111dB for a 0. 2MHz, 1.2Vp-p input signal, sampled at a rate of 2MS/s,about 18dB over the Bootstrapped switch. Also, the on-resistance variation is reduced by 90%. This method is especially useful for low-voltage, high resolution ADCs, which is a hot topic today.