Wootae Kim

Comparison frequency doubling and charge pump matching techniques for dual-band /spl Delta//spl Sigma/ fractional-N frequency synthesizer

The frequency synthesizer with two LC-VCOs is fully integrated in a 0.35-/spl mu/m CMOS technology. In supporting dual bands, all building blocks except VCOs are shared. A current compensation scheme using a replica charge pump improves the linearity of the frequency synthesizer and, thus, suppresses spurious tones. To reduce the quantization noise from a /spl Delta//spl Sigma/ modulator and the noise from the building blocks except the VCO, the proposed architecture uses a frequency doubler with a noise-insensitive duty-cycle correction circuit (DCC) in the reference clock path. Power consumption is 37.8 mW with a 2.7-V supply. The proposed frequency synthesizer supports 10-kHz channel spacing with the measured phase noise of -114 dBc/Hz and -141 dBc/Hz at 100-kHz and 1.25-MHz offsets, respectively, in the PCS band. The fractional spurious tone at 10-kHz offset is under -54 dBc.

A 1.2-V-only 900-mW 10 gb ethernet transceiver and XAUI interface with robust VCO tuning technique

This paper describes the design and the implementation of a fully integrated 10 Gb Ethernet transceiver in a 0.13-/spl mu/m CMOS process using only a 1.2 V supply. A coarse control algorithm that combines a voltage range monitoring circuit with a frequency lock detector provides a robust operation against process, voltage, and temperature (PVT) variations for a VCO with a ring oscillator. With the use of a blind oversampling DPLL architecture, four channels of XAUI transceivers can share a single PLL, eliminating the clock synchronization problem between channels. Also, the total number of clock domains for the entire chip is reduced to three, making the integration of the XAUI with the 10G transceiver much simpler. The test chip consumes 898 mW from a 1.2 V supply.