Search for: All records

This article presents a back-off efficient power amplifier (PA) for mm-wave 5G and upcoming 6G beamforming phased array transceivers (PATs), incorporating advanced circuit designs and novel implementations in both passive and active components. Conventional back-off efficient PAs in the mm-wave frequency range occupy a large chip area, making it hard to fit them into PATs. To overcome this issue, we propose a compact back-off efficient Doherty PA (DPA) with a common base (CB) structure as the core of the PA and small low-loss passive elements. In addition, the proposed architecture moves the role of the input hybrid coupler to the interstage matching network while maintaining DPA functionality. The interstage matching provides the required phases for the main and auxiliary PAs, power division, and impedance matching. The PA prototype is fabricated in the GlobalFoundries 90-nm BiCMOS (9 HP) process. It achieves a peak gain of 20.4 dB at 28.45 GHz with a 1-dB bandwidth of 4.45 GHz. Under large-signal conditions, it archives >19.5-dBm Psat with >36% PAEsat. Its P1dB at 26, 28, and 30 GHz are 19.4, 19.3, and 19.3 dBm with 38.5%, 37.3%, and 36.8% PAE1 dB, respectively. In the 6-dB power back-off region, it reaches efficiencies of 29.1%, 31.1%, and 29.3% at 26, 28, and 30 GHz, respectively. When tested with the NR-FR2 test model at these frequencies, the PA achieves Pavg of 8.25, 8.45, and 8 dBm, and PAEavg of 13.9%, 14.5%, and 13.7% for a 400 M 1-CC 64-QAM signal, maintaining an rms error vector magnitude (EVMrms) of −25.8, −25.8, and −25.7 dB. In addition, in adjacent channel power ratio (ACPR) tests, the PA achieves −27, −26.2, and −30.8 dBc on the lower side and −28.4, −28.5, and −27.6 dBc on the higher side channels at 26, 28, and 30 GHz, respectivelyNot Available 

Millimeter-wave (mmWave) systems require a large number of antennas, which makes the beam training challenging and time-consuming for conventional phased arrays. Recently, a true-time-delay (TTD) array-based beam training algorithm has been shown as an effective solution to overcome the training overhead in large arrays. In this paper, we present a custombuilt over-the-air (OTA) testbed to study the effects of hardware impairments on the TTD-based beam training and verify its feasibility in a real system. We proposed an orthogonal matching pursuit (OMP) based reconstruction algorithm along with a phase calibration dictionary to combat nonidealities such as strong frequency selectivity and phase misalignment in the received raw IQ signal. Post-processing results showed that with the nonideality effects properly handled, the 3D TTD beam training algorithm can achieve high AOA estimation accuracy. 

This article presents a dual-band power amplifier for 28 and 39 GHz frequency bands based on a new dual-path transformer (DPT). This DPT can provide two optimum inductive values at two different frequency bands to optimally design the matching networks for each band without using any switch circuitries. It operates as the output and input matching networks in a parallel power combiner and divider, respectively. DPT-based PA breaks the trade-off between bandwidth and performance in conventional wideband PAs by separating one whole wideband into two narrow bands providing optimum input and output matchings for each band. The DPT-based PA has two input and two output ports. One set of input and output ports is dedicated to a lower frequency band and the other set of input and outport ports can be used for a higher frequency band. Each output port can drive a separate antenna in a phased array for each frequency band. The proposed PA prototype is fabricated in a 65 nm CMOS process achieving 15.3 and 14.0 dBm of saturated output power in 28 and 39 GHz. The peak efficiency of the PA is 34.1% and 30.2% at 28 and 39 GHz frequency bands. The PA has a measured EVM with 64-QAM modulated signal in both frequency bands showing −25.03 and −25.10 dB in the low and higher frequency bands, respectively. 

This article introduces an innovative four-port dual-path inductor designed to deliver two distinct inductance values to the resonator of a voltage-controlled oscillator (VCO). The switching between the inductor’s two excitation modes, even and odd, is determined by the differential excitation’s input polarity, eliminating the need for a series switch. Thus, the inductor has a high-quality factor ( Q ) in both modes. The inductances in these modes can be independently set based on desired frequencies. This inductance change achieves coarse frequency tuning, while fine-tuning is realized by a conventional 2-bit capacitor bank with a small-size varactor. This inductor is well suited for designing multiband VCOs aimed at widely spaced operation frequency bands. Apart from the inductance change, a particular case of mode-switching capacitor is employed to extend to another frequency band in between the low and middle bands, achieving triple-band oscillation. As a result, this article presents two VCOs designed using the proposed inductor: one in class-D biasing in a 65-nm CMOS process and another with class-B biasing in a 180-nm BiCMOS process. Both VCOs successfully oscillate across three distinct frequency bands, centered at 19, 28, and 36 GHz, while maintaining outstanding phase noise and minimal power consumption. Measurement results show good match with simulation, resulting in a peak figure of merit (FoM) of 185.7 dBc/Hz at 18.5 GHz, and occupy 0.088- mm2 (250 × 350 μ m) area in both processes.