A 193-nW Wake-Up Receiver Achieving −84.5-dBm Sensitivity for Green Wireless Communications

A 5.5–7.5‐GHz band‐configurable wake‐up receiver fully integrated in 45‐nm RF‐SOI CMOS

“…Thus, the simulated relative current deviation ΔI 0; rel ¼ � � � I 0;100°− I 0;−40°I 0;20°� � � is 12.4 %. In addition, loaded with a resistor of 50 kΩ in parallel to a capacitor of 100 fF, the F I G U R E 1 0 Schematic of the proposed comparator based on [3], where I 0 = 5 μA F I G U R E 1 1 Simplified schematic of the current reference, where I 0 = 5 μA current achieves its 96 % of steady-state current of 5 μA within 12 ns. As the load resistance is normally less than 50 kΩ, the settling time of the current reference is ensured to be less than 12 ns.…”

“…In a duty‐cycled WuRX, the overall power consumption P WuRX is related to the duty cycle D , the on‐time T ON , direct current (DC) power consumption of the WuRX AFE P ON,AFE , leakage power of the AFE P LEAK,AFE and that of the DBE P LEAK,DBE [3]: $$$\begin{array}{rl}\hfill {P}_{\text{WuRX}}& ={P}_{\text{AFE}}+{P}_{\text{DBE}}\hfill \\ \hfill & =D\cdot {T}_{\text{ON}}\cdot {P}_{\text{ON,AFE}}+{P}_{\text{LEAK,AFE}}+{P}_{\text{LEAK,DBE}}\hfill \end{array}$$$ where P ON,AFE , P LEAK,AFE and P LEAK,DBE are: $$$\left\{\begin{array}{l}{P}_{\text{ON,AFE}}={I}_{\text{ON,AFE}}\cdot {V}_{\text{DD,AFE}}\quad \hfill \\ {P}_{\text{LEAK,AFE}}={I}_{\text{LEAK,AFE}}\cdot {V}_{\text{DD,AFE}}\quad \hfill \\ {P}_{\text{LEAK,DBE}}={I}_{\text{LEAK,DBE}}\cdot {V}_{\text{DD,DBE}}\quad \hfill \end{array}\right.$$$ …”

“…To successfully recover the phase information after wireless transmissions, this work implements 4‐time oversampling of a transmitted symbol, leading to the following relation between the duty cycle, data rate and the on‐time of the receiver [3]: $$$D=4\cdot DR\cdot {T}_{\text{ON}}$$$ …”

“…The latency of a WuRX describes a time period that the WuRX takes from the moment it receives the first symbol of a wake‐up packet until it sends out the power‐on signal to its main radio. Modern WuRXs such as [3, 10, 11, 16, 19–21, 23, 33, 40] deploy a correlator to sense and differentiate their wake‐up code from other codes and noise that appear in the same channel. In this context, the latency directly results from the data rate of a WuRX and the bit length of a wake‐up packet L bit : $$${T}_{\text{lat}}=\frac{{L}_{\text{bit}}}{DR}$$$ …”

“…So far, state-of-the-art WuRXs focus primarily on a high sensitivity by using a possibly low-power consumption. To simultaneously achieve both the metrics, off-chip high-Q components such as high-Q coils [3][4][5][6][7][8][9][10][11], MEMS-based [12][13][14] or BAW-based [15] input matching networks (IMN) were often used. While they provide the WuRXs with a narrow RF bandwidth and a high passive voltage gain, these bulky components also reduce the system compactness and increase the integration cost.…”