A –90 dBm Sensitivity Wireless Transceiver Using VCO-PA-LNA-Switch-Modulator Co-Design for Low Power Insect-Based Wireless Sensor Networks

This paper presents a wireless transceiver intended for insect-based wireless sensor networks (WSNs). The transceiver utilizes several design techniques developed to meet the challenging low power and low size requirements in insect-based WSNs. The techniques include current reuse in the voltage-controlled oscillator (VCO) and power amplifier (PA), fast PLL on/off switching for low-power on/off keying (OOK) modulation, and switching between transmit and receive (TX/RX) modes without an off-chip switch. Also, the VCO, PA, low noise amplifier (LNA), OOK modulator, and TX/RX switch are co-designed and integrated into a single block to reduce the system complexity significantly. The transceiver is designed and fabricated in a 0.13-μm CMOS process. The transmitter provides an output power in the range of -30 dBm to -4.4 dBm while consuming an average power of 1.2 mW to 4.5 mW. The phase locked-loop (PLL) does not use a high-Q external resonator, and its phase noise depends on the PA output power because of the current reuse in the VCO and PA. The PLL phase noise at 1 MHz offset at 2.4 GHz varies from -103.3 dBc/Hz to -116.7 dBc/Hz. The receiver achieves a sensitivity of -90 dBm at 1 Mbps data rate for a BER = 0.1%. An example wireless sensor node design utilizing the proposed wireless transceiver achieves a modest weight of 1 gram, and a small form factor of 12.5 mm × 12.5 mm.