A 28 GHz 8-Bit Calibration-Free LO-Path Phase Shifter using Transformer-Based Vector Summing Topology in 40 nm CMOS

Analysis and design of an innovative 19.5 GHz active phase shifter architecture, implemented in a 0.13 μm BiCMOS SiGe:C process, for beamforming in 5G applications

“…It contributes to a gain, and it is implemented as a traditional cascode with reactive matching but this phase shifter circuit suffers from complexity. The work presented by [11], [12] and [13] presents high resolution and linearity performances but at the expense of complexity, power consumption and die area. Among the prevalent APSs techniques, injection-locked oscillators arrays (ILOAs) are among the most frequently used techniques.…”

“…As stated in [11], increasing the injection strength allows for the achievement of a larger locking range and better phase linearity and resolution between ± 90°. However, the variation of the locking range as a function of the injection strength becomes nonlinear for high values of the injected signal compared to low injection levels, as shown in equations ( 35) and (38).…”

“…Therefore, a larger locking range is obtained when the injection strength is high compared to the case corresponding to a weak injection. In this case, the 𝛥ϕ max depends only on the value of the injection strength 𝑘 = 𝐼 𝑖𝑛𝑗 /𝐼 𝑜𝑠𝑐 and thus it can exceed ± 90° and reach (180°-𝑐𝑜𝑠 -1 (𝑘)) [13], [11].…”