I am trying to cite a paper whose bibtex entry is generated via Google scholar. I am using biblatex to manage my bibliography, however, when trying to compile with xelatex, I got the following error:

! Missing { inserted.
<to be read again> 
l.10 \printbibliography[title=References]

? ! Missing } inserted.

It seems that there is some error in the bibtex entry.

A minimum latex file "see.tex" that reproduces this error is


\usepackage[backend=biber, style=ieee,]{biblatex}





And the content in paper.bib is:

    author={Z. Yan and P. I. Mak and M. K. Law and R. P. Martins}, 
    journal={IEEE Journal of Solid-State Circuits}, 
    title={A 0.016-mm$^{2}$ 144-$\mu$W Three-Stage Amplifier Capable of Driving 1-to-15 nF Capacitive Load With $>$ 0.95-MHz GBW}, 
    keywords={UHF amplifiers;circuit feedback;compensation;GBW;capacitance 1 nF to 15 nF;capacitive load;control-centric method;current-buffer Miller compensation;figure-of-merit;frequency 0.95 MHz;local feedback loop analysis;minimum gain-bandwidth product;parasitic-pole cancellation;pole-zero placements;power 144 muW;size 0.35 mum;slew rate;small-signal FOM;three-stage amplifier;Circuit analysis;Feedback loop;Limiting;Poles and zeros;Stability analysis;Standards;Active LHP zero;CMOS;Miller compensation;current buffer;current buffer Miller compensation;frequency compensation;pole-zero cancellation;three-stage amplifier}, 

I compile my latex file with the following command:

xelatex see
biber see
xelatex see

So, what is wrong with the content in "paper.bib"? And how can I fix it?

  • Never trust automatic bibliography export tools. Always check if the result makes sense. In this case, the hyphens in the title are more than suspicious.
    – Johannes_B
    Dec 9 '17 at 15:02

The title is the problem. The casing is changed from title to sentence style and this breaks \mu. This can be prevented by using curly braces to protect the problematic parts of the title and, where the letter case should not be changed, e.g. the units.


title={A 0.016-mm{$^{2}$} 144-{$\mu$W} Three-Stage Amplifier Capable of Driving 1-to-15 {nF} Capacitive Load With $>$ 0.95-{MHz} {GBW}},


If it is acceptable to add a package dependency to the bibliography data (paper.bib), then the numbers with unit can be set with package siunitx, see Mico's comment. This requires that the document loads the package:


The title entry becomes:

  {\SI[output-decimal-marker=., number-unit-product=-]{0.016}{\milli\meter\squared}}
  Three-Stage Amplifier Capable of Driving
  {\SIrange[range-units=single, range-phrase=-to-]{1}{15}{\nano\farad}}
  Capacitive Load With
  {\SI[output-decimal-marker=., number-unit-product=-]{>0.95}{\mega\hertz}}


  • \SI with arguments also needs to be surrounded by curly braces.
  • The hyphens in 1-to-15 can be added by option range-phrase. The other hyphens between numbers and units are set by option number-unit-product.
  • Option output-decimal-marker is added to prevent that the decimal marker is changed due to other document settings (e.g., if the document is in a different language with different output marker).


Result with siunitx

  • 1
    Even better than ${\mu$W} would be \textmicro{W} or, if the siunitx package is loaded, SI{0.016}{\milli\meter\squared} \SI{144}{\micro\watt}.
    – Mico
    Dec 9 '17 at 12:48
  • I am pretty sure those hyphens are due to a faulty export and should not be in the final result. Rule of thumb: Never trust auto-generated Bib entries.
    – Johannes_B
    Dec 9 '17 at 15:02
  • @Johannes_B There are several versions of the article. I found a version ISSCC 2012 without the hyphens. But the cited article has the hyphens, see JSSC 2013 Dec 9 '17 at 15:10
  • @Mico or Heiko... Which kind of problem we have using a quick and dirty solution including all in a couple of additional {...} ? In the specific case title={{A 0.016-mm$^{2}$ 144-$\mu$W Three-Stage Amplifier Capable of Driving 1-to-15 nF Capacitive Load With $>$ 0.95-MHz GBW}},
    – Hastur
    Dec 13 '17 at 11:40
  • @Hastur Then, the automatic conversion of title case to sentence case does not work anymore. Dec 13 '17 at 16:53

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