A 6-18 GHz 5-Bit Active Phase Shifter

This paper presents a 6-18 GHz active 5-bit phase shifter in 0.18-mu m SiGe BiCMOS technology based on a phase interpolation technique. An L-C resonance-based quadrature all-pass filter generates the I/Q reference signal with high I/Q accuracy over a wide bandwidth, and integrated current-mode DACs control the I/Q amplitudes to achieve 5-bit phase resolution. The phase shifter shows 19.5 dB of power gain with < 1.1 dB of RMS gain variation for all 5-bit phase states at 12 GHz, and the 3-dB gain bandwidth is 7.5-15.2 GHz. The measured RMS phase error is < 3 degrees at 6.4-10.2 GHz and < 5.6 degrees at 6-18 GHz achieving greater than 5-bit accuracy. Within the 3-dB gain bandwidth, the NF ranges from 4 to 5.7 dB and the NF variation is +/- 0.12 dB for all phase states. The total current consumption is IS. 7 mA ( phase shifter core: similar to 3 mA) from a 3.3 V supply voltage and overall chip size is 1.2x0.75 mm(2) ( phase shifter core: 0.45x0.35 mm(2)).