A Self-Calibration Technique for On-Chip Precise Clock Generator

Han, Yan; Qian, Yuji; Sun, Jingru; Zhang, Shifeng

doi:10.1109/tcsii.2015.2468929

Cited by 4 publications

(2 citation statements)

References 8 publications

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“…The coarse calibration logic controls a 7-bit binary weighted current source array, and the binary search method is used to find the coarse current setting such that the relative error ΔN/N is less than ±1% after the coarse calibration. The fine calibration is then deployed to find the appropriate duty cycle ratio D in (2). As shown in Fig.…”

Section: Proposed Calibration Methodmentioning

confidence: 99%

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Crystal‐less oscillator calibration using serial data as frequency reference

2018

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A frequency calibration method for a crystal-less current-controlled ring oscillator is presented. It uses a serial data signal from another chip as the frequency reference. The proposed calibration circuit is composed of the coarse calibration and the fine calibration circuit. The coarse calibration circuit controls a binary weighted biasing current source array, while the fine calibration circuit generates a pulse-width-modulation (PWM) signal to control a switched biasing current source. The duty cycle ratio of the PWM signal is obtained by measuring the frequency ratio error between the oscillator output and the reference signal. An auto-correlation-based method is proposed to calculate the frequency ratio error. The 8 MHz ring oscillator in together with the calibration circuit has been fabricated in a 0.13 μm CMOS process. Measured results on 24 chips show that the relative frequency error is reduced to 0.0239% (mean offset + 3σ) after calibration. The reported oscillator shows advantages in accuracy, power consumption and chip area.

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Section: Proposed Calibration Methodmentioning

confidence: 99%

“…A reference clock with known frequency is usually used to calibrate the crystal-less oscillators. The counter-based method is commonly used for its simplicity [1,2]. This calibration method requires a clock signal with adequate frequency accuracy.…”

mentioning

confidence: 99%