A 25–30-GHz RMS Error-Minimized 360° Continuous Analog Phase Shifter Using Closed-Loop Self-Tuning I/Q Generator

Abstract

A novel wideband analog phase shifter employing a self-tuning <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I/Q$ </tex-math></inline-formula> generator is proposed in this article. It can provide 360° continuous phase shift with very low rms gain and phase error while consuming 22.8 mW from a 1-V supply with the phase shifter core dissipating only 11.2 mW. Cartesian-combining method has been employed to provide better control over sidelobes in a phased array network application. The phase shifter is fabricated in 65-nm CMOS and occupies a core area of only 0.12 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Employing the self-tuning <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I/Q$ </tex-math></inline-formula> generator in an error feedback control loop, a single-stage poly-phase-filter ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> -PPF) is tuned by changing the gate voltage of triode-regime nMOS resistors. This self-tuning-loop provides <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I/Q$ </tex-math></inline-formula> amplitude imbalance and phase error under 0.3 dB and 1.1°, respectively. This reduces the rms gain error and phase error of the phase shifter below 0.4 dB and 1.6° respectively for a 5-GHz bandwidth (25–30 GHz). The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I/Q</i> generator circuit consumes a dc-bias current of only 2 mA. The tunable insertionloss varies by around 7 dB and the 1-dB compression point IP1dB is in the range <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-7.5\,\,\pm \,\,2.6$ </tex-math></inline-formula> dBm near the center frequency. The proposed phase shifter can be a good fit for radio detection and ranging (RADAR) within the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> - and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ka</i> -bands, as well as, for future 5G application in the 26.5–29.5 GHz range.