Analysis and Design of a High-Order Discrete-Time Passive IIR Low-Pass Filter

In this paper, we propose a discrete-time IIR low-pass filter that achieves a high-order of filtering through a charge-sharing rotation. Its sampling rate is then multiplied through pipelining. The first stage of the filter can operate in either a voltage-sampling or charge-sampling mode. It uses switches, capacitors and a simple gm-cell, rather than opamps, thus being compatible with digital nanoscale technology. In the voltage-sampling mode, the gm-cell is bypassed so the filter is fully passive. A 7th-order filter prototype operating at 800 MS/s sampling rate is implemented in TSMC 65 nm CMOS. Bandwidth of this filter is programmable between 400 kHz to 30 MHz with 100 dB maximum stop-band rejection. Its IIP3 is +21 dBm and the averaged spot noise is 4.57 nV/$surd$ Hz. It consumes 2 mW at 1.2 V and occupies 0.42 mm 2.MicroelectronicsElectrical Engineering, Mathematics and Computer Scienc

A Fully Integrated Discrete-Time Superheterodyne Receiver

The zero/low intermediate frequency (IF) receiver (RX) architecture has enabled full CMOS integration. As the technology scales and wireless standards become ever more challenging, the issues related to time-varying dc offsets, the second-order nonlinearity, and flicker noise become more critical. In this paper, we propose a new architecture of a superheterodyne RX that attempts to avoid such issues. By exploiting discrete-time (DT) operation and using only switches, capacitors, and inverter-based gm-stages as building blocks, the architecture becomes amenable to further scaling. Full integration is achieved by employing a cascade of four complex-valued passive switched-cap-based bandpass filters sampled at 4× of the local oscillator rate that perform IF image rejection. Channel selection is achieved through an equivalent of the seventh-order filtering. A new twofold noise-canceling low-noise transconductance amplifier is proposed. Frequency domain analysis of the RX is presented by the proposed DT model. The RX is wideband and covers 0.4-2.9 GHz with a noise figure of 2.9-4 dB. It is implemented in 65-nm CMOS and consumes 48-79 mW.Electronic

A high IIP2 SAW-less superheterodyne receiver with multistage harmonic rejection

In this paper, we propose and demonstrate the first fully integrated surface acoustic wave (SAW)-less superheterodyne receiver (RX) for 4G cellular applications. The RX operates in discrete-time domain and introduces various innovations to simultaneously improve noise and linearity performance while reducing power consumption: a highly linear wideband noise-canceling low-noise transconductance amplifier (LNTA), a blocker-resilient octal charge-sharing bandpass filter, and a cascaded harmonic rejection circuitry. The RX is implemented in 28-nm CMOS and it does not require any calibration. It features NF of 2.1-2.6 dB, an immeasurably high input second intercept point for closely-spaced or modulated interferers, and input third intercept point of 8-14 dBm, while drawing only 22-40 mW in various operating modes.Electronic

Disulfiram induces apoptosis in human melanoma cells: a redox-related process.

Melanoma is highly resistant to conventional chemotherapy. We have demonstrated that redox regulation in melanoma cells is aberrant, and redox-modulating agents can induce cell apoptosis. We have currently explored the effect of disulfiram (DSF), a member of the dithiocarbamate family, on apoptosis of melanoma cells in vitro. Human metastatic melanoma cells c81-46A, c81-61, and c83-2C were treated with DSF and apoptosis measured. DSF, at a dose of 25-50 ng/ml, consistently caused a 4-6-fold increase in apoptosis. The same dose of DSF did not significantly affect apoptosis in melanocytes. Coincubation of N-acetyl-cysteine reversed the DSF-induced apoptosis. Buthionine sulfoximine (BSO), an inhibitor of gamma-glutamyl-cysteine synthetase, as a single agent caused a approximately 2-fold increase in apoptosis when incubated with melanoma cells for 4 days. BSO slightly enhanced the level of apoptosis induced by DSF (4-10% higher than DSF alone). Intracellular glutathione was remarkably depleted with BSO treatment. DSF did not cause glutathione depletion; however, the ratio of reduced and oxidized glutathione was significantly decreased (14% of control), and N-acetyl-cysteine partially restored the ratio to 30% of control. There was a transient (2-fold) elevation of intracellular superoxide level after 24 h of DSF treatment (before the overt apoptosis). The intracellular H2O2 level progressively decreased with time. DSF decreased the mitochondrial membrane polarization in a time-dependent manner, and there was a significant inverse correlation between apoptosis and mitochondrial membrane polarization. We propose that DSF-induced apoptosis is redox related but involves a different mechanism from BSO-induced apoptosis in tumor cells. Our findings have provided new data for additional understanding of drug-induced apoptosis in melanoma cells and suggests an alternative therapeutic approach to melanoma

A Bluetooth Low-Energy Transceiver with 3.7-mW All-Digital Transmitter, 2.75-mW High-IF Discrete-Time Receiver, and TX/RX Switchable On-Chip Matching Network

We present an ultra-low-power Bluetooth low-energy (BLE) transceiver (TRX) for the Internet of Things (IoT) optimized for digital 28-nm CMOS. A transmitter (TX) employs an all-digital phase-locked loop (ADPLL) with a switched current-source digitally controlled oscillator (DCO) featuring low frequency pushing, and class-E/F2 digital power amplifier (PA), featuring high efficiency. Low 1/ f DCO noise allows the ADPLL to shut down after acquiring lock. The receiver operates in discrete time at high sampling rate (10 Gsamples/s) with intermediate frequency placed beyond 1/ f noise corner of MOS devices. New multistage multirate charge-sharing bandpass filters are adapted to achieve high out-of-band linearity, low noise, and low power consumption. An integrated on-chip matching network serves to both PA and low-noise transconductance amplifier, thus allowing a 1-pin direct antenna connection with no external band-selection filters. The TRX consumes 2.75 mW on the RX side and 3.7 mW on the TX side when delivering 0 dBm in BLE.ElectronicsElectronic Components, Technology and Material