# A 920-MHz Dual-Mode Receiver with Energy Harvesting for UHF RFID Tag and IoT +
## 5 Measurement Results  
The dual-mode receiver and energy harvester were fabricated in standard 180 nm CMOS process with a 0.455 mm\({}^{2}\) active area, as shown in Figure 14. The chip was dominated by capacitors of the rectifier and charge pump circuit.  
Figure 12: Simulation results of IF amplifier: (**a**) gain; (**b**) phase.  
Figure 13: Schematic of proposed demodulator including low-pass filter and comparator.  
The chip was connected to the PCB using bond wires. The measurement setup included an Agilent signal generator (E4438C), Agilent oscilloscope (MSO9104A), network analyzer (N5242A) and a digital multimeter (FLUKE). The loose caused by parasitic capacitance and inductance of cable, balun, matching components (\(L_{1,2}\) = 23 nH with Q = 35) and bond wire were measured and calculated as 1.5 dB.  
Figures 15 and 16 show the measured output voltage and PCE of the on-chip switched-capacitor charge pump for variable input voltage (180 mV to 300 mV) and loads (0.5 M\(\Omega\) to 2 M\(\Omega\)). When the load \(R_{L}\) = 1 M\(\Omega\) and input voltage \(V_{IN}\)\(>\)210 mV, the output voltage \(V_{OUT}\)\(>\) 1 V and the output power was more than 1 uW. At \(V_{IN}\) = 0.2 V, the maximum PCE increased to 46.5%.  
Figure 17 shows the measured results of the rectifier's output voltage and PCE for variable loads \(R_{L}\) = 100 k\(\Omega\) and 200 k\(\Omega\). The measured S11 with frequency in 850 MHz to 1 GHz is shown in Figure 18b. The value of S11 was smaller than \(-\)10 dB in range of 900 MHz to 940 MHz, which means the RF port was impedance matched with the antenna. The sensitivity for 1 V output was \(-\)18 dBm @ 200 k\(\Omega\), and the maximum PCE was over 57% @ 100 k\(\Omega\).  
Figure 17: Measurement results of the rectifier, (**a**) output voltage versus input power for \(R_{L}=100\) k\(\Omega\) and 200 k\(\Omega\); (**b**) efficiency versus input power for \(R_{L}=100\) k\(\Omega\) and 200 k\(\Omega\).  
Figure 18: (**a**) Measured input signal and demodulated signal in low-power (LP) mode; (**b**) measured S11.  
The measured waveforms of the dual-mode receiver are shown in Figures 18a and 19a. The transient waveforms of the input RF signal and demodulated baseband output in the minimum incident power demonstrate the sensitivities were \(-18\) dBm and \(-40\) dBm for LP and HS mode, respectively.  
In the HS mode with 10 kbps and 200 kbps data rate, the receiver achieved \(-42\) dBm and \(-40\) dBm sensitivity for the bit error rate (BER) \(<\)0.001 in 920 MHz as shown in Figure 19b.  
The power consumption of each block is shown in Figure 20. The receiver's total power consumption were 230 nW and 880 nW for LP mode and HS mode, respectively. The energy harvester could provide more than \(1\upmu\)W of energy in an indoor environment according to the measurement resulted, so the energy was sufficient to the dual-mode receiver.  
The performance summary is shown in Table 1. The proposed dual-mode receiver achieved relatively high sensitivity without high-Q topology and the proposed architecture was compatible with fully passive operating mode. Furthermore, the RF/PV/TE energy-harvesting approach could eliminate the requirement of battery and extend the lifetime effectively. In this design, small active area, low power consumption and low voltage operation were obtained.  
Figure 19: (a) Measured input signal and demodulated signal in HS mode; (b) bit error rate (BER) in HS mode.  
Figure 20: Measured power consumption of each block.