Silicon CMOS Synthesizes Signals at 60 GHz

Demand for millimeter-wave technology for short-range communications links and automotive safety systems is growing. It was once thought that gallium arsenide (GaAs) semiconductor devices would be the active components of choice for these applications, but silicon CMOS technology is showing that it has not “run out of gas” just yet. A number of researchers supported by the National Research Foundation of Singapore and the School of Electrical and Electronic Engineering of the Nanyang Technological University in Singapore—including Xiang Yi, Chirn Chye Boon, Hang Liu, Jia Fu Lin, and Wei Meng Lim—have demonstrated a frequency synthesizer based on 65-nm silicon CMOS technology. It is capable of high-output signals from 57.9 to 68.3 GHz.

The quadrature phase-lock-loop (PLL) frequency synthesizer exhibits low phase noise at 60 GHz using an in-phase injection-coupled quadrature voltage-controlled oscillator (IPIC-QVCO) with an inductorless divider chain to reduce power consumption. In fact, the QVCO consumes only 11.4-mW power from a +1.2-VDC supply and features better than -92 dBc/Hz phase noise offset 1 MHz from the carrier. The full frequency synthesizer consumes only 24.6-mW power with single-sideband (SSB) phase noise of better than -89.8 dBc/Hz offset 1 MHz from the carrier. The quadrature synthesizer is capable of generating four 2.16-GHz-wide channels—such as channels centered at 58.32, 60.48, 62.64, and 64.80 GHz—in support of IEEE 802.15.3c and other 60-GHz communications standards.

Implemented in standard 65-nm CMOS technology, this frequency synthesizer uses a 3-b binary-weight switch-capacitor bank for discrete tuning. The approach yields less noise than other techniques and covers the four frequency bands with low noise and low VCO gain. The inductorless divider chain operates with about 300 mV peak-to-peak voltage and works across a frequency range of 35 to 77 GHz, with at least 3-GHz bandwidth in each subband. The device was fabricated by means of Global Foundries’ 65-nm low-power CMOS process and shows great promise for low-power millimeter-wave communications applications. See “A 57.9-to-68.3 GHz 24.6 mW Frequency Synthesizer With In-Phase Injection-Coupled QVCO in 65 nm CMOS Technology,” IEEE Journal of Solid State Circuits, February 2014, p. 347.  

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