Search

This paper proposes an adaptive RF front-end (RFFE) architecture that uses an electrical-balance duplexer (EBD) and tuned surface acoustic wave (SAW) resonators to enable adaptive dual-frequency isolation suited for LTE's frequency-division duplex (FDD) mode of operation. Alternatively, in the in-band full-duplex (IBFD) mode, the EBD cancels the in-band TX self-interference directly at RF for increased channel capacity. Furthermore, the EBD's balance network is optimized to reduce the TX insertion loss (IL) below the nominal 3-dB limit in the FDD mode. A 0.18-μm SOI CMOS prototype implements the EBD, low-noise amplifier, and SAW-tuning capacitor banks. The chip is mounted to a module substrate together with the SAWs and matching components. The RFFE achieves >50-dB dual-frequency isolation and 2.6-3.4-dB TX IL in FDD mode, has +58/+42-dBm TX/RX-path IIP3 for an increased IBFD-link budget and handles up to +27.5-dBm TX power in both modes. [ABSTRACT FROM AUTHOR]

An electrical-balance duplexer achieving the state-of-the-art linearity and insertion loss (IL) performance is presented, enabled by a partially depleted RF silicon-on-insulator CMOS technology. A single-ended configuration avoids the common-mode isolation problem suffered by topologies with a differential low-noise amplifier. Highly linear switched capacitors allow for impedance balancing to antennas with <1.5:1 voltage standing wave ratio from 1.9 to 2.2 GHz. +70-dBm input-referred third-order intercept point is achieved under high transmitter (TX) power (+30.5 dBm max.). TX IL is <3.7 dB, and receiver IL is <3.9 dB. [ABSTRACT FROM PUBLISHER]

In this paper, we present an intensive study of 6T-SRAM designs for vertical gate-all-around (GAA) transistors (VFETs) and lateral GAA transistors (LFETs) using 5-nm node design rules. Optimizations of the nanowire (NW) diameter and the gate length are also conducted to enhance the SRAM performance. Device VT retargeting has been proposed for improving the minimum operating voltage ( V\min ) of SRAMs. The isoperformance and isoyield have been performed to assess and determine the benefits provided by LFET and VFET architectures, respectively. Our results show that the VFET bitcells are denser than the LFET bitcells by 20%–30%. The SRAM read stability (read static noise margin) is significantly improved using the NW channel. For a $6\sigma $ yield target and an isoarea of SRAM bitcells, V\min of the VFET bitcell is 80 mV lower than LFET designs. Applying the proposed VT retargeting technique can allow the VFET 122 bitcell to operate at 0.57 V without using assist circuits. A standby leakage below 10 pA/cell can be achieved for both architectures. At isoperformance, the standby leakage of VFET bitcells is $2.6\times $ lower than LFET bitcells. [ABSTRACT FROM AUTHOR]

Millimeter-wave sensors perform robust and accurate remote motion sensing. We propose a 28 nm CMOS Radar TX that modulates a 79 GHz carrier with a 2 Gsps Pseudo-Noise sequence. The measured modulated output power at 79 GHz in 4 GHz BW is higher than +11 dBm (27^\circC), while the spurious emissions are below -20 dBc, fully satisfying the spectral mask regulations. The output RF BW where we can lock the injection-locked LO is 13 GHz. Overall, the TX draws 121 mW from a 0.9 V supply resulting in a record efficiency above 10%. More importantly, the TX is functional up to 125 ^\circC still providing more than +7 dBm output power over the same RF BW. [ABSTRACT FROM AUTHOR]

This brief presents an improved timing scheme for a 4 $\times$ interleaved 6-bit pipelined binary search (PLBS) analog-to-digital converter (ADC). The individual channel consists of a calibrated fully dynamic PLBS architecture with a 1-bit folding front-end. This work enhances the ADC conversion rate up to 3.5 GS/s, for 4.1-mW power consumption. The peak spurious-free dynamic range and signal-to-noise-plus-distortion ratio (SNDR) are 44.1 and 31.2 dB, respectively, measured for low input frequency. With near-Nyquist input frequency, the SNDR drops to 29.5 dB, yielding an energy-per-conversion step of 48 fJ. The prototype has been fabricated in a 40-nm low-power digital CMOS process. The ADC active area is 250 \times 120\ \mu\m^2. [ABSTRACT FROM AUTHOR]

A charge-domain SAR ADC is presented which integrates the current of a variable-gain transconductor on its sampling capacitor, rather than being driven by a power hungry voltage buffer. The sampling circuit uses nonlinear MOS capacitors as sampling capacitor for passive amplification to relax the comparator noise requirements without compromising linearity. The prototype in 40 nm low power CMOS process consists of a 1.1–17.6 mS transconductor, combined with a 10 b 0–80 MS/s charge-sharing SAR ADC. It achieves 70 dB DR while consuming less than 5.45 mA from a 1.1 V supply and achieves a peak SNDR of 56.85 dB at 40 MS/s. [ABSTRACT FROM PUBLISHER]

A low-power impulse-radio ultra-wideband receiver is demonstrated for low data-rate applications. A topology selection study demonstrates that the quadrature analog correlation is a good receiver architecture choice when energy consumption must be minimized. The receiver operates in the 3.1-5 GHz band of the UWB FCC spectrum mask on channels of 500 MHz bandwidth. The pulse correlation operation is done in the analog domain in order to reduce the ADC sampling speed down to the pulse repetition rate, thereby reducing the power consumption. The receiver comprises a low-noise amplifier with full on-chip matching network, an RF local oscillator generation, two quadrature mixers, two analog baseband chains followed by two ADCs, and a clock generation network. The receiver is implemented in 0.18 μm CMOS technology and achieves 16 mA power consumption at 20 Mpulses/s pulse repetition rate. [ABSTRACT FROM AUTHOR]

Substrate noise generated by the digital circuits on a mixed-signal IC can severely disturb the analog and RF circuits sharing the same substrate. Simulations at the circuit level of the substrate noise coupling in large systems-on-chip (SoCs) do not provide the necessary understanding in the problem. Analysis at a higher level of abstraction gives much more insight in the coupling mechanisms. This paper presents a physical model to estimate and understand the substrate noise generation by a digital modem, the propagation of this noise and the resulting performance degradation of LC tank VCOs. The proposed linearized model is fast to derive and to evaluate, while remaining accurate. It is validated with measurements on two test structures: a reference design and a design with a p+/n-well (digital) guard ring. Both structures contain a functional 40k gate digital modem and a 0.18 µm 3.5 GHz CMOS LC-VCO on a lightly-doped substrate. In both cases, the model accurately predicts the level of the spurious components appearing at the VCO output due to the digital switching activity. The error remains smaller than 3 dB. Finally, we demonstrate how the proposed model enables a systematic and controlled isolation strategy to suppress substrate noise coupling problems. As an example, the model is used to determine suitable dimensions for a digital guard ring. [ABSTRACT FROM AUTHOR]

In mixed analog-digital designs, digital switching noise is an important limitation for the performance of analog and RF circuits. This paper reports a physical model describing the impact of digital switching noise on LC-tank voltage-controlled oscillators (VCOs) in lightly doped substrates. The model takes into account the propagation from the source of substrate noise to the different components in the VCO and the resulting modulation of the oscillator frequency. The model is validated with measurements on a 3.5-GHz LC-tank VCO designed in 0.18-µm CMOS. It reveals that for this VCO, impact occurs mainly via the nonideal metal ground lines for lower frequencies and low tuning voltage and via the integrated inductors for higher frequencies and high tuning voltage. To make the design immune to substrate noise, the parasitic resistance of the on-chip ground interconnect has to be kept as low as possible and inductors have to be shielded. Hence, the developed model allows investigating the dominant mechanisms behind the impact of substrate noise on a VCO, which is crucial information for achieving a substrate noise immune design. [ABSTRACT FROM AUTHOR]