A high resolution and wideband CMOS LO phase shifter

A new active LO phase shifter is introduced and implemented in a 2×2 MIMO receiver using STMicroelectronics 90nm CMOS technology. One of the advantaged of this new phase shifter is its capability of achieving very high resolution phase shifting over a wide range of frequencies which makes it suitable for multi-standard wireless applications. The proposed phase shifter is fully transistor based and it is digitally controlled. Measurement shows that phase shifter is able to change the phase of the output base band signal by 360° when LO is varying from 1.5GHz to 6GHz. the average resolution of the phase shifter is 1.32ps which is equivalent to 0.7 and 2.9 degree at 1.5GHz and 6GHz respectively. The differential I&Q signals are swapped to reduce the phase shift requirement of the phase shifter.