9 A Current-mode CMOS Frequency-insensitive Quadrature Phase Shifter

In this paper, a quadrature phase shifter is presented. Due to operation in current-mode, the proposed circuit provides a wide frequency response, a low supply voltage, low power consumption and electronic controllability. Thus, it is very suitable for use in portable and battery-powered equipment such as hearing aid instrument and wireless radio device. The proposed quadrature phase shifter consists of differentiator, current-mode precision rectifier, current-mode low pass filter and current controlled amplifier, which can be fabricated into Integrated Circuit (IC) form. The feature of the proposed circuit is that it can provide the quadrature signals with frequency-insensitivity. The performances of the proposed circuit are explored through HSPICE simulation program using BSIM3V3 model from AMIS, they demonstrate good agreement to the theoretical anticipation. The proposed circuit works at ±1V supply voltages, power consumption is merely 16.8µW