This paper presents a 16 MHz frequency reference that exploits the well-defined thermal diffusivity of IC-grade silicon. After a room temperature trim, its absolute inaccuracy is ±0.1% from -55°C to 125°C (24 samples), while its cycle-to-cycle jitter is less than 45 ps (rms) at a power dissipation of 2.1 mW from a 1.8 V supply. The reference occupies 0.5 mm2 in a 0.16 μ m standard CMOS process. Compared to a previous design in an older 0.7 μm CMOS process, it achieves 10× higher frequency, 7× less jitter, 3.7× less power, and 12x less chip area, while maintaining the same level of accuracy.

A Scaled Thermal-Diffusivity-Based 16 MHz Frequency Reference in 0.16 µm CMOS

A new topology for phase-shift control in the transmitter module of phased array antennas is introduced. The proposed structure is based on a hybrid DDS-PLL approach. An offset-PLL evolution is proposed in order to preserve phase resolution, along with a maximum phase shift of 360°. Experimental results obtained by a prototype are reported, validating the architecture potentialities.

Phase shifter based on DDS-driven offset-PLL

A transceiver was designed and fabricated in 65 nm CMOS to verify the feasibility of using a free running, on-chip LC tank as the local oscillator in an IEEE 802.15.4 transceiver. The elimination of the off-chip frequency reference is possible while still using a standards based narrow-band architecture. A free running LC tank is shown to have frequency stability better than ± 40 ppm in the absence of temperature changes. Demodulator-based feedback is implemented to allow a receiver to track transmitter drift due to varying environmental factors and phase noise. The modulation accuracy of a free-running open loop Minimum Shift Key (MSK) transmitter is shown to be within the limits set by IEEE 802.15.4.

Crystal-free narrow-band radios for low-cost IoT

This paper introduces and demonstrates with high yield a novel concept for the packaging under vacuum of tuning fork quartz XTALs on top of a silicon interposer equipped with TSVs. It paves the way to the implementation of a monolithic timing microsystem where the ASIC is part of the housing of a newly designed tiny 131-kHz XTAL to reach extreme module miniaturization (1.5 × 1.1 × 0.7 mm 3) and integrity. As this task is still ongoing, an early demonstration of the generic versatile timing module is presented using a chip-on-board approach with standalone conventionally packaged XTAL and BAW resonators. The module achieves 0.4 μW power dissipation and ±2 ppm stability over -40 °C to 85 °C in RTC mode and can deliver on-demand programmable clocks between 1-50 MHz. The latter are obtained either with a RC PLL or after division of the signal obtained from a 2-GHz BAW DCO at a power dissipation of 100 μW and 5.3 mW, respectively.

A Versatile Timing Microsystem Based on Wafer-Level Packaged XTAL/BAW Resonators With Sub- $\mu$ W RTC Mode and Programmable HF Clocks

This work presents a new all CMOS Self-Compensated Oscillator (SCO) that is highly stable across temperature and is utilized as a reference clock source. The new architecture utilizes an innovative phase shift technique that adjusts the phase of the tank at a specific Temperature Null (TNULL) phase where the frequency deviation across temperature is minimized. The single LC tank architecture used in the new oscillator reduces die area significantly compared to a previously reported dual LC tank architecture. The new oscillator achieves a total frequency stability of ±100ppm across temperature (−40–85°C), supply (3.0–3.6V) and load (0–15pF). CMOS output frequencies from 1–133MHz can be produced with a 2.8ps rms period jitter and 7mA current consumption at 25MHz output.

A single LC tank self-compensated CMOS oscillator with frequency stability of ±100ppm from −40°C to 85°C

A highly stable all silicon Self-Compensated Oscillator (SCO) reference source is presented. Self compensation across temperature is achieved using a newly discovered phenomenon in LC-tanks named the Temperature Null (TNULL) which has been described and briefly analyzed. A quadrature oscillator architecture has been used to implement the SCO in a 0.18μm CMOS technology. The SCO has on-chip infrastructure facilitating low cost trimming and frequency calibration at room temperature. Excellent frequency stability of ±50ppm has been measured across temperature (0 − 70°C), 3.0 − 3.6V supply and 1 − 15pF load. The SCO has a programmable frequency range of 1 − 133MHz, consumes 7.1mA at 25MHz and has an RMS period jitter of 2ps at 125MHz.

A highly stable CMOS Self-Compensated Oscillator (SCO) based on an LC tank temperature Null concept

OBJECTIVES: There is an increasing trend to perform the bidirectional superior cavopulmonary (Glenn) anastomosis without cardiopulmonary bypass. In this report, we present our results of off-pump bidirectional Glenn operation done without using a venoatrial shunt to decompress the randomized comparative study was superior vena cava during clamping. METHODS: A prospective, non-randomized comparative study was conducted in 50 patients with functional single ventricle anomalies who underwent bidirectional Glenn anastomosis without cardiopulmonary bypass. The patients were divided into two groups: Group I (n= 25), where it was done without a veno-atrial shunt, and Group II (n= 25), where it was done with a veno-atrial shunt. Two patients in Group I and 4 patients in Group II had a bilateral bidirectional Glenn shunt. Five patients in Group I and three patients in Group II had a previous left modified Blalock–Taussig shunt. All patients underwent a complete neurological examination both preoperatively as well as postoperatively. RESULTS: The early hospital mortality was 4% (2/50), one in each group. The median follow-up was 14 months. The mean internal venous pressure on clamping the superior vena cava was 37.07 ± 7.12 mmHg in Group I and 24 ± 4.4 mmHg in Group II. The mean clamp time was 9.85 ± 3.52 min in Group I and 21.3 ± 4.4 min in Group II. The transcranial pressure gradient was 62.37 ± 15.01 mmHg in Group I, while 65.08 ± 13.89 in Group II. The mean intensive care unit stay was 2.57 ± 75 days in Group I, 3.3 ± 1.09 in Group II. There were no major neurological complications apart from treatable convulsions in one case in Group I (4%), 2 cases in Group II (8%), and delayed recovery in one case (4%) in Group I.

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Cavopulmonary anastomosis without cardiopulmonary bypass.

The nonlinear behavior of common-emitter (CE) and single-balanced BJT mixer (SBM) circuits is described by a simple closed-form interpretable analytical expression. The third-order intermodulation distortion (IM3) calculated by this approach is in good agreement with harmonic-balance results of an APLAC circuit simulator for different input signal level, biasing current, emitter degeneration and operating frequency range. In addition, the model can successfully identify the bias currents that lead to a minimum or maximum amount of distortion. Therefore, it provides an easy guideline for the designer to directly optimize the linearity performance among other conflicting performance parameters; gain, noise and power dissipation.

A simplified analytical model for nonlinear distortion in RF bipolar circuits

A simple analytical approach for nonlinear distortion in RF bipolar circuits is utilized in the evaluation of spurious free dynamic range (SFDR) in BJT circuits. Simple closed-form expressions can predict the critical bias conditions corresponding to minimum or maximum SFDR. This method is applied to low noise amplifier (LNA) and single balanced mixer (SBM) circuits to study and optimize the dynamic range. The proposed method can predict the dynamic range with less than 10% error in most cases. The validity of this technique is examined by comparing the results of SPICE simulations to the calculations of the proposed method under different operating conditions.

A. Helmy

Papers

A single LC tank self-compensated CMOS oscillator with frequency stability of ±100ppm from −40°C to 85°C

A highly stable CMOS Self-Compensated Oscillator (SCO) based on an LC tank temperature Null concept

Cavopulmonary anastomosis without cardiopulmonary bypass.

A simplified analytical model for nonlinear distortion in RF bipolar circuits

On the SFDR performance of BJT RF circuits, an analytical approach