A 10-bit 200-MS/s CMOS parallel pipeline A/D converter

This paper describes a 10-bit 200-MS/s CMOS parallel pipeline analog-to-digital (A/D) converter that can sample input frequencies above 200 MHz. The converter utilizes a front-end sample-and-hold (S/H) circuit and four parallel interleaved pipeline component A/D converters followed by a digital offset compensation. By optimizing for power in the architectural level, incorporating extensively parallelism and double-sampling both in the S/H circuit and the component ADCs, a power dissipation of only 280 mW from a 3.0-V supply is achieved. Implemented in a 0.5-μm CMOS process, the circuit occupies an area of 7.4 mm². The converter achieves a differential nonlinearity and integral nonlinearity of ±0.8 LSB and ±0.9 LSB, respectively, while the peak spurious-free-dynamic-range is 55 dB and the total harmonic distortion better than 46 dB at a sampling rate of 200 MS/s     

A 22-mA 3.0-dB NF direct conversion receiver for 3G WCDMA

A 2-GHz single-chip direct conversion receiver achieves a 3.0-dB double-sideband noise figure, -14-dBm IIP3 and +17-dBm IIP2 with 60-mW power consumption from a 2.7-V supply. The receiver is targeted for the third generation UTRA/FDD WCDMA system. The low power consumption has been achieved with a proper partitioning and by avoiding buffering between blocks. In the differential RF front end, current boosted quadrature mixers follow the variable-gain low-noise amplifier. At the baseband, on-chip ac-coupled highpass filters are utilized to implement amplification with variable gain having small transients related to gain steps. The outputs of the analog channel selection filters are sampled directly by the two single-amplifier 6-bit pipeline A/D converters. The spurious tones due to the feedthrough of clock harmonics to the RF input increase the noise figure less than 0.1 dB. The receiver has been fabricated with a 0.35-μm 45-GHz f_T SiGe BiCMOS process     

A Direct Digital Synthesizer with Tunable Delta Sigma Modulator

In direct digital synthesizer (DDS) applications, the drawback of the conventional delta sigma () modulator structure is that its signal band is fixed. In the new architecture presented in this paper, the signal band of the modulator is tuned according to the DDS output frequency. We use a hardware efficient phase-to-sine amplitude converter in the DDS that approximates the first quadrant of the sine function with sixteen equal length second degree polynomial segments. The DDS is capable of frequency, phase, and quadrature amplitude modulation. Two DDSs with tunable 1-bit D/A converters (real and complex) were designed and implemented on a programmable logic device (PLD); experimental results show their desired operation and performance.     

Impulse sensitivity function-based phase noise study for low-power source-coupled CMOS multivibrators

In this paper, two micropower frequency references implemented with a 0.13- and a 0.25-μm CMOS process for low-power sensor applications are presented. Both circuits are based on a power-optimized source-coupled CMOS multivibrator. The 2.0-MHz frequency reference uses a nominal 1.8–2.5-V supply voltage. The 24.6/307.2-kHz frequency reference is an evolution of the 2.0-MHz reference and operates with a lower supply of 1.0 V and provides two active operating modes. With 1-pF load capacitances, the 2.0-MHz and 24.6/307.2-kHz frequency references typically consume 6.7 μA and 230/750 nA, respectively. After presenting experimental results relating to frequency trimming and frequency stability, this paper concentrates on the phase noise study of the proposed frequency references. The procedure used to apply the impulse sensitivity function-based (ISF) phase noise method to CMOS oscillators is described in detail. The phase noise results of both the implemented references obtained with this method agree well with the measurements.     

Off-axis re-entrant cavity ring-down spectroscopy with a mid-infrared continuous-wave optical parametric oscillator

We demonstrate an off-axis cavity ring-down spectroscopy system, which uses a mid-infrared continuous-wave optical parametric oscillator as a light source. Off-axis injection with re-entrant configuration of the ring-down cavity is used to achieve high spectral resolution while maintaining high measurement speed. This makes the setup suitable for sensitive molecular spectroscopy in the mid-infrared region, particularly for studies that require high temporal resolution. Formaldehyde (H₂CO) absorption spectrum at 3.4 µm is measured using the off-axis re-entrant cavity ring-down spectrometer.     

Direct detection of acetylene in air by continuous wave cavity ring-down spectroscopy

Diode laser-based continuous wave cavity ring-down spectroscopy (cw-CRDS) in the near-infrared region has been used to measure the mixing ratio of acetylene (C₂H₂) in ambient air. Detection limits of 120 parts per trillion by volume (pptv) for 20 min and 340 pptv for 70 s acquisition time were achieved without sample pre-concentration, measuring on a C₂H₂ absorption line at 6565.620 cm^?1 (～1523 nm). Several indoor and outdoor air samples were collected at different locations in the Helsinki metropolitan area and analyzed using static-cell measurements. In addition, flow measurements of indoor and outdoor air have been performed continuously over several days with a time resolution of down to one minute. Baseline acetylene levels in the range of 0.4 to 3 parts per billion by volume (ppbv), with a maximum around midday and a minimum during the night, were measured. Sudden high mixing ratios of up to 60 ppbv were observed in outdoor air during daytime on a minute time scale. In general, the indoor mixing ratios were found to be higher than those in outdoor air. The acetylene levels correlated with the ambient CO levels and with outdoor temperature.     

Low-noise amplifiers for WCDMA base-station receivers

This paper focuses on the design and measurements of low-noise amplifiers (LNA) targeted for WCDMA base-station applications. In addition, various gain control techniques and the accuracy in noise measurements have been analyzed. Two different LNA designs are presented. Both LNAs can be operated in two gain modes, which are optimized for different base-station configurations. Both designs are implemented using the same 0.25-μm SiGe BiCMOS process, and both designs achieve the NF of 1 dB and IIP3 of ?5 dBm in high gain mode.