A 0.028-mm2 32-MHz RC Frequency Reference With an Inaccuracy of ±900 ppm From -40 °C to 125 °C and ±1600 ppm After Accelerated Aging

Journal Article (2025)
Author(s)

Sining Pan (Tsinghua University)

Yihang Cheng (Tsinghua University)

Guohua Wu (Tsinghua University)

Zhihua Wang (Tsinghua University)

K.A.A. Makinwa (TU Delft - Microelectronics)

Huaqiang Wu (Tsinghua University)

Department
Microelectronics
DOI related publication
https://doi.org/10.1109/JSSC.2025.3530944
More Info
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Publication Year
2025
Language
English
Department
Microelectronics
Bibliographical Note
Green Open Access added to TU Delft Institutional Repository as part of the Taverne amendment. More information about this copyright law amendment can be found at https://www.openaccess.nl. Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public. @en
Issue number
9
Volume number
60
Pages (from-to)
3257-3267
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Abstract

This article describes the design and implementation of a compact CMOS RC frequency reference based on N-type diffusion (N-diff) resistors and metal-insulator-metal (MIM) capacitors. It consists of a frequency-locked loop (FLL) that locks the period of a voltage-controlled oscillator (VCO) to the time it takes a current source to charge a capacitor to a reference voltage. Conventionally, the temperature compensation of such FLLs involves the use of resistors with different temperature dependencies. In this work, however, this is done by using two bipolar junction transistor (BJT)-based current sources with different temperature dependencies to charge a MIM capacitor and generate a reference voltage across an N-diff resistor, respectively. Implemented in a standard 180-nm technology, the resulting frequency reference achieves small size (0.028 mm2), moderate inaccuracy (±900 ppm) from -40 °C to 125 °C, and low drift (±1600 ppm) after accelerated aging. The versatility of the proposed temperature compensation scheme is validated by replacing the N-diff resistor with a P-poly resistor. However, the latter exhibits greater inaccuracy (+2000/-2500 ppm) and more drift (-2600/-8100 ppm) after accelerated aging.

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