A Wideband Active Vector-Sum Phase Shifter With Impedance Compensation

An active vector-sum phase shifter (VSPS) using a wideband I/Q network and a vector synthesizer with output impedance compensation is presented in this letter. A differential quadrature all-pass filter (QAF) with additional inductors <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L_{C}$</tex-math> </inline-formula> and capacitors <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C_{C}$</tex-math> </inline-formula> exhibits wideband performance and robustness against load effect. To achieve stable output impedance of the vector synthesizer at different phase states, an impedance compensation structure using a pair of dummy transistors is connected in parallel at the output of the Gilbert cell-based vector synthesizer. The VSPS prototype is implemented in 65-nm CMOS process, which exhibits a measured maximum rms gain error of 0.55 dB and an rms phase error of less than 2.1° with a phase resolution of 5.625° over 2441 GHz. The fractional bandwidth (FBW) is 52.3%. The power consumption is 11.2 mW, and the core size of the whole chip is 0.144 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>.