Design of A Voltage-Controlled Oscillator Based on Butterworth Bandpass Filter

In this paper, a first-order Butterworth bandpass filter is connected to a VCO to reduce phase noise (PN), power consumption, and size. The first-order Butterworth BPF design methodology is depending on quasi-lumped elements, in which the filter consists of a meander transmission line and metal-insulator-metal (MIM) capacitors. The design of a simple LC-equivalent circuit model is demonstrated. A cross-coupled differential VCO with a BPF is presented in $0.13-\mu \mathrm{m}$ SiGe BiCMOS technology. The large coils in VCO are replaced by BPF with a high quality factor, and the filter significantly reduces the size, power consumption, and phase noise for VCO. The result of VCO with connected BPF is $0.067 \mathrm{~mm}^{2}$ for active area, the power consumption is $4.98 \mathrm{~mW}$, and the $\mathrm{FoM}_{\mathrm{A}}$ is $194.3 \mathrm{~dB}$. The simulated Frequency carrier and PN are 22GHz and $-102.7 \mathrm{dBc} / \mathrm{Hz}(-122.5 \mathrm{dBc} / \mathrm{Hz})$ at $1-\mathrm{MHz}(10 \mathrm{MHz})$ offset frequency, respectively, which results in a FOM of $182.6 \mathrm{~dB}$.