An ultra‐wideband (UWB) low‐noise amplifier (LNA) using a 0.11 µm CMOS technology is proposed. The common‐gate (CG) input stage for wideband input impedance matching and the common‐source (CS) stage for noise cancelling are applied. In the proposed LNA, the current of the CG input stage can be significantly reduced by applying the g _m ‐boosting technique using the noise‐cancelling CS stage without additional amplifier, and the noise performance can be improved at the same power consumption. For low‐power operation, the LNA consumes 2.9 mW and achieves a noise figure (NF) of S ₂₁ between 16.5 and 17.6 dB at S ₁₁ , lower than −12.4 and 3.6–3.7 dB at frequencies of 3–10 GHz. In low‐noise operation, the LNA consumes 8.3 mW, achieving S ₁₁ of less than −10.7 dB, S ₂₁ of 17.5–18.7 dB, and NF of 2.4–2.9 dB.

In this paper, an optimal design of a high-efficiency DC-DC boost converter is proposed for RF energy harvesting Internet of Things (IoT) sensors. Since the output DC voltage of the RF-DC rectifier for RF energy harvesting varies considerably depending on the RF input power, the DC-DC boost converter following the RF-DC rectifier is required to achieve high power conversion efficiency (PCE) in a wide input voltage range. Therefore, based on the loss analysis and modeling of an inductor-based DC-DC boost converter, an optimal design method of design parameters, including inductance and peak inductor current, is proposed to obtain the maximum PCE by minimizing the total loss according to different input voltages in a wide input voltage range. A high-efficiency DC-DC boost converter for RF energy harvesting applications is designed using a 65 nm CMOS process. The modeled total losses agree well with the circuit simulation results and the proposed loss modeling results accurately predict the optimal design parameters to obtain the maximum PCE. Based on the proposed loss modeling, the optimally designed DC-DC boost converter achieves a power conversion efficiency of 96.5% at a low input voltage of 0.1 V and a peak efficiency of 98.4% at an input voltage of 0.4 V.

A CMOS cross‐coupled RF rectifier that improves power conversion efficiency (PCE) with low reverse leakage current for energy harvesting wireless sensors is proposed. In this Letter, the authors propose a CMOS cross‐coupled differential RF rectifier that uses a thick‐oxide MOSFET as a rectifying device to improve PCE by reducing reverse leakage current. The proposed rectifier is designed for UHF band application using 0.18 µm CMOS technology. Proposed rectifier achieves a peak PCE of 75.2% and sensitivity of − 17 dBm for 1 V output voltage. Peak PCE is improved by 8.8% compared to the conventional rectifier.

In this paper, a dual-band wide-input-range adaptive radio frequency-to-direct current (RF–DC) converter operating in the 0.9 GHz and 2.4 GHz bands is proposed for ambient RF energy harvesting. The proposed dual-band RF–DC converter adopts a dual-band impedance-matching network to harvest RF energy from multiple frequency bands. To solve the problem consisting in the great degradation of the power conversion efficiency (PCE) of a multi-band rectifier according to the RF input power range because the available RF input power range is different according to the frequency band, the proposed dual-band RF rectifier adopts an adaptive configuration that changes the operation mode so that the number of stages is optimized. Since the optimum peak PCE can be obtained according to the RF input power, the PCE can be increased over a wide RF input power range of multiple bands. When dual-band RF input powers of 0.9 GHz and 2.4 GHz were applied, a peak PCE of 67.1% at an input power of −12 dBm and a peak PCE of 62.9% at an input power of −19 dBm were achieved. The input sensitivity to obtain an output voltage of 1 V was −17 dBm, and the RF input power range with a PCE greater than 20% was 21 dB. The proposed design achieved the highest peak PCE and the widest RF input power range compared with previously reported CMOS multi-band rectifiers.

In this paper, a fully integrated capacitive DC-DC boost converter for ultra-low-power internet of things (IoT) applications operating with RF energy harvesting is proposed. A DC-DC boost converter is needed to boost the low output voltage of the RF energy harvester to provide a high voltage to the load. However, a boost converter operating at a low voltage supplied by ambient RF energy harvesting has a problem in that power conversion efficiency is significantly lowered. The proposed on-chip capacitive DC-DC boost converter simultaneously applies gate bias boosting and dynamic body biasing techniques using only the internal boosted voltage without an additional circuit that increases power loss to boost the voltage, achieving high efficiency at an input voltage as low as 0.1 V. The designed capacitive boost converter achieves a peak power conversion efficiency (PCE) of 33.8% at a very low input voltage of 0.1 V, a 14% improvement over the peak PCE of the conventional cross-coupled charge pump. A maximum peak PCE of 80.1% is achieved at an input voltage of 200 mV and a load current of 3 μA. The proposed capacitive boost converter is implemented with a total flying capacitance of 60 pF, suitable for on-chip integration.

A Gaussian pulse generator for an ultra‐wideband impulse radio transmitter is presented. The proposed generator is based on digital intensive circuits, and the centre frequency and bandwidth of a pulse are controlled by a digitally tunable delay circuit and pulse‐width control circuit. The Gaussian pulse is obtained by a weighted summing amplifier that is controlled by a digital switching signal without an additional LC filter. The amplifier uses a Gaussian pulse shaper that has tunable weighting factors with bandwidth control. The energy consumption of the pulse generator is 37.4 pJ/pulse, and sidelobe rejection of 20 dB is achieved without a filter.