Low power Controlled Ring Oscillator with Complementary Drain Capacitance (CRO-CDC) for UWB Applications

The Ring Oscillator (RO) is a ubiquitous element in the high-speed Phase Locked Loop (PLL) to decide the output frequency for timing controls. Since Digitally Controlled Ring Oscillators (DCRO) with variable output frequency offer more feasibility to the PLL, 3-stage digitally Controlled RO with Complementary Drain Capacitance (CRO-CDC) are presented in this article. The proposed ROs are realized using (i) basic negator, (ii) NAND negator and (iii) NOR negator along with CDC to attain wider tuning range of 440 MHz, 697 MHz and 144 MHz respectively. The proposed CRO-CDC are implemented in 180 nm CMOS technology with supply voltage of 1.8 V and simulated using spectre circuit simulator. The negator RO with CDC (NRO_CDC) achieves variable output frequency ( \(\hbox {f}_{OUT}\) ${\text{f}}_{\mathit{OUT}}$ ) of 5.179 \(-\) $-$ 5.619 GHz consuming power of 786.3 \(\mu\) $\mu$ W. The NAND negator RO with CDC (NdNRO_CDC) exhibits \(\hbox {f}_{out}\) ${\text{f}}_{\mathit{out}}$ range of 2.729 \(-\) $-$ 2.873 GHz consuming 944.5 \(\mu\) $\mu$ W. The NOR negator RO with CDC (NrNRO_CDC) attains \(\hbox {f}_{out}\) ${\text{f}}_{\mathit{out}}$ range of 3.467 \(-\) $-$ 4.164 GHz and consumes 595 \(\mu\) $\mu$ W. The simulated phase noise (PN) and Figure-of-Merit (FoM) of the proposed CRO-CDC are \(-\) $-$ 88.5 dBc/Hz @ 1 MHZ offset and 126.18 dB respectively.