An Analog Automatic-Amplitude Control Circuitry for Ultra-wideband LC VCO in 0.18 µm CMOS

A stand-alone configurable analog automatic-amplitude control (AAC) circuit is presented for ultra-wideband (UWB) voltage control oscillator (VCO), which helps to keep the UWB VCO at reasonable output amplitude over process, voltage, and temperature (PVT). The proposed architecture of VCO with AAC is designed in 0.18 µm CMOS, and consumes 22 mA from a 3.3-V supply voltage. Transistor-level post-simulated results indicate that the 3.2 – 7 GHz multi-core UWB LC VCO is capable of providing the phase noise performance of −124 and −119 dBc/Hz at 1-MHz offset from 3.2 GHz and 7 GHz carrier, respectively. The variation coefficient of the output single-ended amplitude is no more than 4.5% in all various circumstances, and it hardly worsens phase noise to VCO. One of the attractive points to emerge from the proposed UWB VCO is that the response time could save 40% over traditional architecture, and it could be widely used in other symmetrical/differential types.