180° Switching Method Based on Transformer for CMOS Phase Shifter

A novel 180 <tex-math notation="LaTeX">∘</tex-math> switching method based on transformer for phase shifter (PS) is proposed. The proposed method provides low phase error (PE) and low gain error, which enhances the overall performance of the PS. To demonstrate the feasibility of the proposed circuit configuration, the PS is implemented using a 65-nm bulk complementary metal–oxide–semiconductor (CMOS) process. Using the proposed 180 <tex-math notation="LaTeX">∘</tex-math> -unit structure, a fully integrated PS with a resolution of 6 bits shows the rms PE of 2.4 <tex-math notation="LaTeX">∘</tex-math> –3.0 <tex-math notation="LaTeX">∘</tex-math> and the rms gain error of 0.8–1.0 dB with <tex-math notation="LaTeX"><</tex-math> <tex-math notation="LaTeX">$-10$</tex-math> dB of input and output return loss ( <tex-math notation="LaTeX">S₁₁</tex-math> , <tex-math notation="LaTeX">S₂₂</tex-math> ). The measured insertion loss is 9.3 dB at 24 GHz. The power dissipation of PS is zero and the core size is 0.18 mm <tex-math notation="LaTeX">^2</tex-math> .