A 0.14nJ/b 200Mb/s Quasi-Balanced FSK Transceiver with Closed-Loop Modulation and Sideband Energy Detection

As the demand of high-speed communication is growing for mobile connectivity, the design of a low-power high-data-rate wireless transceiver is essential. Even though the binary FSK (BFSK) modulation is a popular choice for low-power transceiver systems [1]–[5], it has difficulty in achieving a high data rate unless an open-loop oscillator or an injection-pulling oscillator [6] is employed. The direct modulation of the VCO with an open-loop method or within a narrowband PLL suffers from the pulling effect. A closed-loop modulation based on the PLL is challenging for the high data rate due to a limited loop bandwidth or a delay mismatch in the case of the two-point modulation. Moreover, the closed-loop BFSK modulation suffers from a data-pattern-dependency problem when a wideband PLL is considered. The binary frequency-domain OOK (BFOOK) modulation method provides a way of achieving a fully-balanced FSK modulation [7]–[8], so that a wideband PLL can be designed to minimize the VCO pulling effect. The BFOOK modulation, however, occupies twice as much bandwidth as the conventional BFSK modulation. In this work, we propose a quasi-balanced FSK (QB-FSK) modulation to achieve enhanced bandwidth efficiency, while having negligible data-pattern dependency. Based on the proposed modulation method, we present a sub-6GHz FSK transceiver that achieves the highest data rate with the PLL-based modulation.