公开(公告)号：US20170179975A1

公开(公告)日：2017-06-22

申请号：US15360984

申请日：2016-11-23

Applicant: Analog Devices Global

Inventor： YUNZHI DONG ,  Hajime SHIBATA ,  Trevor Clifford CALDWELL ,  Zhao LI ,  Jialin ZHAO ,  Jose Barreiro SILVA

IPC: H03M3/00

CPC classification number: H03M3/422 ,  H03M1/361 ,  H03M3/322 ,  H03M3/344 ,  H03M3/378 ,  H03M3/388 ,  H03M3/414 ,  H03M3/436 ,  H03M3/464

Abstract: For continuous-time multi-stage noise shaping analog to digital converters (CT MASH ADCs), quantization noise cancellation often requires estimation of transfer functions, e.g., a noise transfer function of the front end modulator. To estimate the noise transfer function, a dither signal can be injected in the front end modulator. However, it is not trivial how the dither signal can be injected, since the dither signal can potentially leak to the back end modulator and cause overall noise degradation. To address some of these issues, the dither signal is injected post the flash analog to digital converter (ADC) of the front end modulator. Furthermore, dummy comparator structures can be used to synchronize the dither with the quantization noise of the targeted flash ADC.