UC San Diego

Two 4-bit active phase shifters integrated with all digital control circuitry in 0.13-mu m RF CMOS technology are developed for X- and Ku-band (8-18 GHz) and K-band (18-26 GHz) phased arrays, respectively. The active digital phase shifters synthesize the required phase using a phase interpolation process by adding quadrature-phased input signals. The designs are based on a resonance-based quadrature all-pass filter for quadrature signaling with minimum loss and wide operation bandwidth. Both phase shifters can change phases with less than about 2 dB of RMS amplitude imbalance for all phase states through an associated DAC control. For the X- and Ku-band phase shifter, the RMS phase error is less than 10 degrees over the entire 5-18 GHz range. The average insertion loss ranges from -3 dB; to -0.2 dB at 5-20 GHz. The input P-1dB for all 4-bit phase states is typically - 5.4 +/- 1.3 dBm at 12 GHz in the X- and.Ku-band phase shifter. The K-band phase shifter exhibits 6.5-13 degrees of RMS phase error at 15-26 GHz. The average insertion loss is from -4.6 to -3 dB at 15-26 GHz. The input P-1dB of the K-band phase shifter is -0.8 +/- 1.1 dBm at 24 GHz. For both phase shifters, the core size excluding all the pads and the output 50 Omega matching circuits, inserted for measurement purpose only, is very small, 0.33 x 0.43 mm(2). The total current consumption is 5.8 mA in the X- and Ku-band phase shifter and 7.8 mA in the K-band phase shifter, from a 1.5 V supply voltage.