一种具有采样带宽补偿的高性能采样/保持电路

针对中频采样模数装换器中的宽带采样/保持电路,提出了一种新颖的电荷交换补偿(CEC)技术.该技术通过消除采样开关有限导通电阻的影响,补偿了采样带宽,并避免了时钟馈通和电荷注入的加剧.同时设计了具有AB类输出的低功耗两级运放,在1.8V电源下为该采样/保持提供了3V峰-峰值的输入范围.该采样/保持电路在100Ms/s的采样率下,对于200MHz输入信号达到了94dB的无杂散动态范围.在5.5pF的负载下,功耗仅为26mW.

A High-Performance Sample-and-Hold Circuit with Sampling Bandwidth Compensation

A novel charge exchanging compensation (CEC) technique is proposed for a wideband sample-and-hold (S/H)circuit applied in an IF sampling ADC. The CEC technique compensates the sampling bandwidth by eliminating the impact from finite on-resistance of the sampling switch, and avoids increasing clock feedthrough and charge injection. Meanwhile,a low power two stage OTA with a class AB output stage is designed to provide the S/H a 3Vp-p input range under 1.8V power. The S/H achieves a 94dB spurious-free dynamic range for a 200MHz input signal at a 100Ms/s sample rate and consumes only 26mW with a 5.5pF load.