2:1 Injection-Locked Frequency Dividers Using Multi-Resonance Spiral-Inductor Resonator

Abstract

This article describes two low-power and wide locking range capacitive cross-coupled divideby-2 injection-locked frequency dividers (ILFDs) implemented in TSMC standard 0.18 μm processes. The ILFDs are based on a differential VCO with one direct injection MOSFET for coupling the external signal to the spiral-inductor resonator. The first/second ILFD uses five/three on-chip inductors in series with parasitic varactors as a multi-resonance resonator. Three measured features are identified. The ILFDs have two non-overlapped locking ranges at low input power, they have two free-running oscillation frequency bands, and the frequency tuning versus gate bias of cross-coupled transistors shows the frequency tuning hysteresis. The power consumption of the 5-L ILFD core is 5.43 mW and the locking range is 6.07 GHz (116.395%) from 2.18 to 8.25 GHz at injection power Pinj =0 dBm. At the supply voltage of 1.1 V, the divider's free-running oscillation frequency is 3.13 GHz. The die area of the 2nd chip is 0.865 × 0.872 mm2. The locking range at low input power is larger for the 5-L resonator ILFD.

Keywords

• Varactor-less divide-by-2 injection-locked frequency divider
• frequency tuning hysteresis
• distributed resonator
• tunable resonator