Active and continuous compensation of clock jitter in continuous time Delta-Sigma ADCs

时间连续δ - σ adc受时钟抖动的影响，因为时钟边缘控制DAC的脉冲宽度，从而直接干扰反馈信号。为了减少时钟抖动的影响，今天主要使用开关电容，也与电阻（SCR-DAC）或多位dac结合使用。缺点是较高的转换速率要求和较高的电路复杂性。另一种建议是基于SC积分器，它将参考电荷与在时钟周期内集成的参考电流进行比较，并由此导出用于抖动补偿的校正信号。这里的关键是kT/ c噪声和电荷注入与时钟抖动的小绝对值相比。此外，该方法基于开关电容，这在连续时间δ - σ ADC中实际上是不可取的。本课题研究并实现了用有源方法对连续时间δ - σ adc中时钟抖动的影响进行连续时间补偿。该原理是基于DAC基准的交替上下集成和在几个时钟周期内集成值的比较。在比较的基础上，产生一个校正信号，该信号在随后的时钟相位馈送到积分器中，从而补偿时钟抖动带来的误差。该方法的优点是在时钟周期内连续积分，因此对补偿电路中的kT/ c噪声和电荷注入的灵敏度较低。只有配上补偿电路，使其本身不受明显的干扰和噪声的影响，才能对时钟抖动进行有源补偿。

Time-continuous delta-sigma ADCs are affected by clock jitter because the clock edges control the pulse width of the DAC and thus directly disturb the feedback signal. To reduce the influence of the clock jitter today mainly switched capacitors, also in conjunction with resistors (SCR-DAC), or multi-bit DACs are used. The disadvantage are higher slew rate requirements respectively a higher circuit complexity. Another proposal is based on an SC integrator, which compares a reference charge with a reference current integrated over the clock period and derives therefrom a correction signal for the jitter compensation. Critical here is the kT/C-noise and the charge injection compared to the small absolute value of the clock jitter. Moreover, the method is based on a switched capacitance, which is actually undesirable in continuous time delta-sigma ADC.In the project, a continuous-time compensation of the influence of the clock jitter in continuous-time delta-sigma ADCs with an active method is to be researched and realized. The principle is based on alternately up and down integration of the DAC reference and comparison of the integrated values over several clock periods. Based on the comparison, a correction signal is to be generated, which is fed into the integrator in subsequent clock phases and thus compensates for the error from the clock jitter. The advantage of this method is the successive continuous-time integration over the clock periods and thus a lower sensitivity to kT/C-noise and charge injection in the compensation circuit. Only with a compensation circuit, which itself is not subject to significant interference and noise, active compensation of the clock jitter can work.