Low Phase Noise Wideband Research Articles

X-band CMOS VCO for 5 GHz Wireless LAN

The implementation of a low phase noise voltage controlled oscillator (VCO) is important for the signal integrity of wireless communication terminal. A low phase noise wideband VCO for a wireless local area network (WLAN) application is presented in this paper. A 6-bit coarse tune capacitor bank (capbank) and a fine tune varactor are used in the VCO to cover the target band. The simulated oscillation frequency tuning range is from 8.6 to 11.6 GHz. The proposed VCO is desgned using 65 nm CMOS technology with a high quality (Q) factor bondwire inductor. The VCO is biased with 1.8 V VDD and shows 9.7 mA current consumption. The VCO exhibits a phase noise of –122.77 and -111.14 dBc/Hz at 1 MHz offset from 8.6 and 11.6 GHz carrier frequency, respectively. The calculated figure of merit(FOM) is -189 dBC/Hz at 1 MHz offset from 8.6 GHz carrier. The simulated results show that the proposed VCO performance satisfies the required specification of WLAN standard.

Design of high efficiency PLL independent LC oscillator for biomedical transceivers

Most digital synchronous ASIC designs requires clk source to provide proper timing for information signals, which functions among all circuits in the biomedical blocks. In such cases the clk source is mostly a crystal oscillator. Commonly such oscillators achieve up to 30 MHz without giving too much trouble. Recent advances and biomedical applications required very high frequency designed using Phased Lock Loop (PLL) free LC oscillators with minimum jitter, phase noise, low power, and wide tuning range. It is most useful block to generate clk signal for ASIC designers. It also gives timing flexibility to counteract clk conveyance delays, modify arrangement and hold times, right clk obligation cycles and limit clk slant and jitter. Essentially yield stage clamor of PLL free oscillator is contributed by LCO, PFD and information reference signal. The choice of circle data transmission is significant so as to accomplish a low jitter low stage clamor LCO. In this thesis novel low jitter low phase noise wide band LCO using self-aligned PLL free LCO in 18 nm CMOS technology is implemented and analyzed.

Comb Spacing Multiplication Enabled Widely Spaced Flexible Frequency Comb Generation

We experimentally demonstrate a new approach for the generation of widely spaced flexible optical frequency combs in a highly nonlinear fiber (HNLF) using relatively low-speed components. A cavity-less 10-GHz optical pulse source is passively multiplied to 50 GHz via the fractional temporal Talbot effect. The repetition rate multiplied pulse train then propagates in an HNLF together with a continuous-wave probe laser to achieve comb spacing multiplication through cross-phase modulation. Numerical study shows that the timing jitter of the initial 10-GHz optical pulse induces insignificant excess phase noise at high-frequency offset relative to the optical comb lines, which favors a low phase noise wideband frequency comb generation. The spectral linewidth of the central 17 comb lines are characterized, exhibiting well-preserved linewidth quality as the probe laser. Furthermore, the tunability of the generated comb, relevant from a practical perspective, is analyzed by means of conversion efficiency. Finally, the central 11 comb lines are individually modulated by Nyquist-shaped 32 GBaud 16 quadratic-amplitude modulation signals, demonstrating the applicability of the comb source in providing optical carriers for a coherent transmitter.