Study of 18.2-42.0 GHz Injection-Locked Frequency Doubler with Transformer Input

Abstract

This paper presents ultra-wideband 18.2-42.0 GHz LC injection-locked frequency doubler (ILFD) with transformer inputs. To expand the locking range, the proposed ILFD incorporates the transformer connected to the source of the gain-cell transistor to obtain high linearity of the input circuitry, moreover, the input matching frequency shifts from the free-run frequency of the oscillator. The measured maximum locking range exhibited 79.1% from 18.2 GHz to 42.0 GHz output at 0 dBm input power and the locked phase noise at 1MHz offset from 28 GHz carrier frequency was −112.1 dBc/Hz under 1.7 mW power consumption. Also, the lowest locked phase noise at 1 MHz offset from the carrier was −122.8 dBc/Hz under 21.2 mW power consumption, and it was only 2.2 dB degraded from the theoretical value. The process technology used in this work was TSMC-180nm CMOS.