Robert H. M. van Veldhoven

A 14b 200MS/s DAC with SFDR>78dBc, IM3<−83dBc and NSD<−163dBm/Hz across the whole Nyquist band enabled by dynamic-mismatch mapping

A 14-bit 200MS/s current-steering DAC with a novel digital calibration technique called dynamic-mismatch mapping (DMM) is presented. Compared to traditional static-mismatch mapping and dynamic element matching, DMM reduces the nonlinearities caused by both amplitude and timing errors, without noise penalty. This 0.14µm CMOS DAC achieves a state-of-the-art performance of SFDR>78dBc, IM3<−83dBc and NSD<−163dBm/Hz across the whole Nyquist band.

A Ratiometric Readout Circuit for Thermal-Conductivity-Based Resistive CO 2 Sensors

This paper reports a readout circuit for a resistive CO2 sensor, which operates by measuring the CO2-dependent thermal conductivity of air. A suspended hot-wire transducer, which acts both as a resistive heater and temperature sensor, exhibits a CO2-dependent heat loss to the surrounding air, allowing CO2 concentration to be derived from its temperature rise and power dissipation. The circuit employs a dual-mode incremental delta-sigma ADC to digitize these parameters relative to those of an identical, but isolated, reference transducer. This ratiometric approach results in a measurement that does not require precision voltage or power references. The readout circuit uses dynamically-swapped transducer pairs to cancel their baseline-resistance, so as to relax the required dynamic range of the ADC. In addition, dynamic element matching (DEM) is used to bias the transducer pairs at an accurate current ratio, making the measurement insensitive to the precise value of the bias current. The readout circuit has been implemented in a standard 0.16 μm CMOS technology. With commercial resistive micro-heaters, a CO2 sensing resolution of about 200 ppm (1σ) was achieved in a measurement time of 30 s. Similar results were obtained with CMOS-compatible tungsten-wire transducers, paving the way for fully-integrated CO2 sensors for air-quality monitoring.

15.7 A 1.65mW 0.16mm2 dynamic zoom-ADC with 107.5dB DR in 20kHz BW

Audio codecs for automotive applications and smartphones require up to five stereo channels to achieve effective acoustic noise and echo cancellation, thus demanding ADCs with low power and minimal die area. Zoom-ADCs should be well suited for such applications, since they combine compact and energy-efficient SAR ADCs with low-distortion ΔΣ ADCs to simultaneously achieve high energy efficiency, small die area, and high linearity [1,2]. However, previous implementations were limited to the conversion of quasi-static signals, since the two ADCs were operated sequentially, with a coarse SAR conversion followed by, a much slower, fine ΔΣ conversion. This work describes a zoom-ADC with a 20kHz bandwidth, which achieves 107.5dB DR and 104.4dB SNR while dissipating 1.65mW and occupying 0.16mm2. A comparison with recent state-of-the-art ADCs with similar resolution and bandwidth [3-7] shows that the ADC achieves significantly improved energy and area efficiency. These advances are enabled by the use of concurrent fine and coarse conversions, dynamic error-correction techniques, and an inverter-based OTA.

17.5 A 0.07mm 2 2-channel instrumentation amplifier with 0.1% gain matching in 0.16μm CMOS

Extremely small-area sensor front-ends are required for cost-constrained automotive applications. Instrumentation amplifiers (IA) for such front-ends must process multi-channel sensor outputs and provide gain matching over the channels for proper sensor operation. Angular sensors are a typical example, in which the sine and cosine outputs of a resistive magnetic sensor must be processed with adequate gain matching to avoid unacceptable angular errors. This paper presents a 2-channel instrumentation amplifier in 0.16μm CMOS with 0.1% gain matching and occupying 0.035mm2 per channel. This represents a 13.3× area improvement with respect to state-of-the-art designs with similar gain accuracy [1]-[4], while maintaining low noise (18.7nV/√Hz), low offset (17μV) and high power efficiency (NEF=12.9). The accurate gain matching in a limited area is enabled by the adoption of a dynamic element matching (DEM) scheme and by the use of a high chopping frequency.

A 0.1-mm 2 3-channel area-optimized ΣΔ ADC in 0.16-µm CMOS with 20-kHz BW and 86-dB DR

Front-ends for automotive sensors must digitize multiple channels with high resolution while minimizing their silicon area to save costs. Both channel latency and inter-channel gain mismatch must be minimized to be able to serve multiple sensor applications, ranging from ABS to power steering, with the same front-end. The proposed ΣΔ ADC simultaneously digitizes 3 channels, each with a DR of 86 dB over a 20-kHz BW using a 75-MHz clock. Channel latency is <;40 ns and inter-channel gain mismatch is <;0.2%. The ADC occupies only 0.1 mm2 in a 0.16-μm CMOS process. The small area is enabled by channel multiplexing, allowing component sharing among the channels, and by the large oversampling ratio (OSR), allowing for smaller capacitors.

ΣΔ Modulator Efficiency

A way of determining the quality of an A/D converter design is to evaluate its performance parameter-cost ratios. A Figure-of-Merit (FOM) relates ΣΔ modulator performance and cost parameters. With a FOM it can be determined whether a design efficiently uses its secondary inputs compared to other designs presented in literature. A benchmark over existing ΣΔ modulator implementations yields the state-of-art FOM with their individual performance and cost parameters as inputs.

Continuous-time Sigma-Delta Modulators for Highly Digitised Receivers

This paper presents an overview of recent developments in continuous-time sigma-delta modulator design. Traditionally, sigma-delta modulators have been used for audio applications with low bandwidth and high-resolution requirements. Nowadays, the area of sigma-delta modulation has extended and sigma-delta modulators are widely used in multi-mode communication receivers with different bandwidth and resolution specifications. Thanks to new architectures and the integration of extra functionality, the excellent power efficiency, as well as good scalability, continuous-time sigma-delta modulators are key in enabling highly digitized receivers.

A Hybrid ADC for High Resolution: The Zoom ADC

This paper presents a dynamic zoom ADC for audio applications. It achieves 109-dB DR, 106-dB SNR, and 103-dB SNDR in a 20-kHz bandwidth, while dissipating 1.12 mW and occupying only 0.16 mm2 in 0.16-μm CMOS. This translates to state-of-the-art energy and area efficiency. In this paper, the system- and circuit-level design of the ADC will be presented.

A ratiometric readout circuit for thermal-conductivity-based resistive gas sensors

This paper presents a readout circuit for thermal-conductivity-based resistive gas sensors. It digitizes the sensors heat loss to its environment, which is a function of gas concentration, relative to that of a reference transducer, which is made of the same material and acts as a thermal-conductivity reference. Thus, dedicated voltage, power or temperature references are not needed. The ratiometric interface is based on a reconfigurable delta-sigma modulator that digitizes both the temperature and power ratio of the sensor and reference transducers, from which their thermal-conductivity ratio is calculated. It uses a dynamic baseline-resistance cancellation technique to relax the required dynamic range. In addition, dynamic element matching and 6-bit bias-current trimming are used to suppress errors due to transducer mismatch. The interface has been implemented in a standard 0.16 μm CMOS technology. Experimental results obtained in combination with CMOS-compatible tungsten-wire transducers show a CO2 resolution of 228 ppm (1σ), which is the highest resolution reported for thermal-conductivity-based CO2 sensors.

Sensors for automotive applications: Challenges and solutions

One of the main drivers of todays IC industry is the electrification of the car, which is a trend that has been already ongoing for several decades. This trend has led to an increasing need for more measurement and control in automotive systems, tasks for which high performance angular, speed and torque sensors are essential components. To enhance the cars comfort, safety and efficiency, these sensors are applied in power steering, ABS and motor management systems respectively. Accordingly, driving experience is increased.