Dual-band adjustable and reactive I/Q generator with constant resistance for down- and up-converters

Sheng C. Tseng*, Chin-Chun Meng, Yueh Ting Lee

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Adjustable and reactive in-phase/quadrature (I/Q) generators with constant resistance are proposed for the first time in this paper with the properties of low loss, dual-band implementation, and high quadrature accuracy. The quadrature phase property and input matching of the I/Q generator can be achieved at all frequencies simultaneously by the constant-resistance I/Q generator. However, the magnitude balance of the dual-band I/Q generator is achieved at two designed frequencies. A 2.4/5.2-GHz I/Q down-converter and a 2.4/5.7-GHz single-sideband up-converter are fabricated using 0.35-/zm SiGe BiCMOS technology. The dual-band I/Q generator along with two single-to-differential amplifiers is integrated to provide differential quadrature local oscillator signals for dual-band mixers. The magnitude imbalance and phase error between the I and Q channels of the down-converter are <1% and < 1°, respectively, while the maximum sideband rejection ratio of the up-converter is up to 50 dB. Additionally, the operation bandwidth (sideband rejection ratio >30 dB) is 200 MHz at 2.4 GHz and 720 MHz at 5.7 GHz.

Original languageEnglish
Article number4548503
Pages (from-to)1861-1868
Number of pages8
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number8
StatePublished - 1 Aug 2008


  • Down-converter
  • Dual band
  • In-phase/quadrature (I/Q)
  • SiGe BiCMOS
  • Single sideband (SSB)
  • SSB rejection ratio
  • Up-converter

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