Search

A 5.8GHz four-channel transmitter RF beamforming IC based on a vector modulator fabricated via the 130 nm RF CMOS process is presented here. The vector modulator controls the gain and phase independently by steering the tail current sources of a Gilbert-cell-based vector synthesizer. It offers 8-bit phase control for 360 ∘ and 4-bit gain control for a 20 dB dynamic range, with the size not depending on the control bits. A four-way differential RF power divider is introduced to implement the four-channel IC, in which off-chip ground bonding inductance is resonated out through the introduction of additional capacitances to a λ/4 impedance transformer of a four-way Wilkinson divider to reduce the insertion losses and errors. The measured total RMS gain error of the vector modulator is 0.312 dB and the total RMS phase error is 0.329 ∘. It shows 20 mW DC power consumption per channel, 5.19 dBm OP1dB, and a 3 dB gain overall including 6 dB of dividing loss.

This article presents two millimeter-wave frequency reconfigurable dual-band CMOS power amplifiers (PAs) for fifth-generation (5G) communications comprising a single-stage dual-band PA and a two-stage dual-band PA for higher gain. The PAs cover multiple 5G communication bands, n257 (26.5-29.5 GHz) and n260 (37-40 GHz), which use reconfigurable transmission line transformers (TLTs) for output, input, and interstage matching networks. These matching networks allow the operating frequency bands to be changed, thereby achieving optimum performance. The integrated mode selection switches in the transformers reconfigure the inductances of the TLTs to cover two frequency bands, which allows the PAs to have small overall chip sizes. These are fabricated in a 28-nm bulk CMOS process. The single-stage dual-band PA achieves 20.2-/19.1-dBm saturated output power ( ${P}_{sat}$ ), 18.7-/18.6-dBm 1-dB compressed output power ( ${P}_{1 dB}$ ), and 33.6%/32% peak power-added efficiency (PAE) at 26.5 and 37 GHz, respectively, while occupying a chip area of 0.11 mm². The two-stage dual-band PA achieves 19.1-/19.5-dBm ${P}_{sat}$ , 17-/17.8-dBm ${P}_{1 dB}$ , and 31.3%/30.5% PAE at 26.5 and 37 GHz, respectively, while occupying a chip area of 0.165 mm². Both PAs are tested under 64-quadrature amplitude modulation signals with a 100-MHz channel bandwidth. The single-stage PA achieves 14.7- and 12.3-dBm average output powers ( ${P}_{avg}$ ) with -25.1- and -25-dB error vector magnitudes (EVMs) at 26.5 and 37 GHz, respectively. The two-stage PA achieves 12.3- and 11.6-dBm ${P}_{avg}$ 's with -25.3- and -25.1-dB EVMs at 26.5 and 37 GHz, respectively.

A differential four-way power divider for 24 to 30 GHz and a frequency reconfigurable differential four-way power divider for 24 to 30 GHz and 37 to 43.5 GHz are presented. The differential structure provides sound virtual grounds in a multiple-channel chip. Both circuits have a four-way Wilkinson power divider (WPD) configuration based on lumped elements that provide small chip sizes. The first one has a small core chip area of 0.09 mm², a small insertion loss of 0.93 to 1.94 dB, and the port-to-port isolation of 19.1 to 25.6 dB from 24 to 30 GHz. It has a small amplitude and phase differences at four outputs. The second one allows frequency-reconfigurable operation by switching inductances and capacitances to cover widely separated frequency bands (5G NR n257-n261 bands). In addition, switched capacitors (SCs) are inserted to resonate out the parasitic series inductances in isolation resistors at both bands of 24-30 GHz and 37-43.5 GHz. It has a core chip area of 0.168 mm², insertion losses of 1.65-1.89 dB at 24 to 30 GHz and 2.04-2.70 dB at 37 to 43.5 GHz, respectively. The port-to-port isolations are 23.4-37.6 dB at 24 to 30 GHz and 22.6-28.4 dB at 37 to 43.5 GHz.

This article proposes a method to detect vocal signals and the corresponding locations of multiple humans using a multiple-input and multiple-output (MIMO) frequency-modulated continuous-wave (FMCW) radar system. The signals of multiple humans are extracted with digital beamforming by the virtual array generated by MIMO radar processing. To remove body motion artifacts that distort the speech information detected by the radar, a body motion effect cancellation method is proposed. The technique allows recovering vocal signals from detected distorted signals by estimating phase variations due to body motions. A combination of the proposed vocal signal detection algorithm with a human localization one enables to detect speaking humans by means of the MIMO radar. Experiments verify that the proposed method can accurately locate and detect speaking humans based on their vocal vibration signals.

A Ka -band CMOS two-stage Doherty power amplifier (DPA) is presented, whose back-off efficiency is improved by voltage-mode Doherty load modulation. The input and output networks of its power stage are composed of transmission line transformers (TLTs) and single-ended Doherty networks implemented with lumped elements. An adaptive bias circuit to boost the Doherty operation is included in the gate network of the auxiliary amplifier. It shows a power gain of 16.2 dB with 48.2% peak drain efficiency (DE) and 25% 6-dB back-off DE at 26 GHz. It has two times higher 6-dB back-off efficiency in comparison to that of a theoretical class-A power amplifier. It is fabricated in a 28-nm bulk CMOS process and occupies 0.094-mm2 core size.