A Fast Tracking and Wide Swing CMOS Peak Detector for On-Chip Q-Factor Measurement

Abstract

In this paper, a CMOS peak detector is proposed in order to satisfy the requirement of an on-chip time-domain quality factor (Q-factor) measurement. Unlike a conventional peak detector in which an Operational Trans-conductance Amplifier (OTA) is used as the core circuit, a high-speed comparator is deployed as the core circuit within the proposed peak detector. As a result, the proposed peak detector can offer a fast peak tracking with a high dynamic range and over a large voltage swing while still covering a wide frequency span with an excellent linearity and accuracy, which are key features required by on-chip Q-factor measurement. The proposed circuit was implemented in a CMOS 0.35μm technology under 5V. The experimental results have shown an output swing almost 4Vpp for an input signal amplitude ranging from 0.02V to 1.9V with a maximum signal dynamic ratio of 50 (Vmax/Vmin), an excellent linearity with a relative error <0.2%, a peak tracking accuracy less than 0.7% for 1MHz and a fast peak tracking with only one period delay in the worst case. The experimental results show that the operating frequency spans from 100 kHz to 5MHz and power consumption is around 9mW within this frequency range.