A 6–18 GHz 5-bit active phase shifter

This paper presents a 6-18 GHz active 5-bit phase shifter in 0.18-μm SiGe BiCMOS technology based on a phase interpolation technique. An L-C resonance-based quadrature allpass 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 S-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° at 6.4-10.2 GHz and <; 5.6° 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 18.7 mA (phase shifter core: ~3 mA) from a 3.3 V supply voltage and overall chip size is 1.2×0.75 mm² (phase shifter core: 0.45×0.35 mm²).