A 24 GHz Wide-Tuning-Range CMOS Digitally Controlled Oscillator for Automotive Radar

Abstract

This paper presents a 24-GHz CMOS oscillator for the automotive radar application that has a digitally controlled wide tuning range. The current digitally controlled oscillator (DCO) topology is chosen to reduce power consumption on the circuit. Furthermore, to minimize tank inductive losses; to increase the transconductance and to improve the phase noise of the DCO, capacitive source-degenerated negative resistors are employed. The proposed DCO utilizes capacitive-feedback technique to increase the output power and phase noise level. The capacitive-feedback technique has been introduced by coarse tuning capacitive cell (CTC) and fine tuning capacitive cell (FTC) that are parallel to the n/pMOS source terminals to increase the oscillation range of the DCO. Specific tuning mechanism is applied to design a wide-tuning-range DCO. Using 130 nm CMOS process the proposed DCO is implemented. A wide tuning range of 23.8 GHz to 26.7 GHz with CTC and 23.8 GHz to 24.9 GHz with FTC are achieved simultaneously. The proposed DCO showed low-phase noise of −104.4 dBc/Hz at 1 MHz offset and low power consumption of 721.5 μW at power supply of 0.9 V.KeywordsCapacitive-feedback technique24 GHzCurrent-reuse structureWide tuning range