A. Marquez

A CMOS low-power 12-bit digitally programmable analog sinusoidal actuation system

This paper presents a CMOS 1.8 V–0.18 μm quadrature sinusoidal oscillator designed for its application as the actuation system in portable frequency-domain sensing devices, such as impedance spectroscopy or resonant readout systems. It is based on an analog implementation, to preserve low-voltage low-power operation with a compact topology. The oscillation frequency can be digitally set by a novel custom 12-bit current programmable architecture from 24 to 477 kHz with high accuracy, constant 1.2 Vp-p output amplitudes and total harmonic distortion below −36 dB over all the range for a power consumption lower than 2 mW.

A CMOS Self-Contained Quadrature Signal Generator for SoC Impedance Spectroscopy

This paper presents a low-power fully integrated quadrature signal generator for system-on-chip (SoC) impedance spectroscopy applications. It has been designed in a 0.18 μm-1.8 V CMOS technology as a self-contained oscillator, without the need for an external reference clock. The frequency can be digitally tuned from 10 to 345 kHz with 12-bit accuracy and a relative mean error below 1.7%, thus supporting a wide range of impedance sensing applications. The proposal is experimentally validated in two impedance spectrometry examples, achieving good magnitude and phase recovery results compared to the results obtained using a commercial LCR-meter. Besides the wide frequency tuning range, the proposed programmable oscillator features a total power consumption lower than 0.77 mW and an active area of 0.129 mm2, thus constituting a highly suitable choice as stimulation module for instrument-on-a-chip devices.

A 0.18 μm CMOS LDO Regulator for an On-Chip Sensor Array Impedance Measurement System

This paper presents a fully integrated 0.18 μm CMOS Low-Dropout (LDO) Voltage Regulator specifically designed to meet the stringent requirements of a battery-operated impedance spectrometry multichannel CMOS micro-instrument. The proposed LDO provides a regulated 1.8 V voltage from a 3.6 V to 1.94 V battery voltage over a −40 °C to 100 °C temperature range, with a compact topology (<0.10 mm2 area) and a constant quiescent current of only 7.45 μA with 99.985% current efficiency, achieving remarkable state-of-art Figures of Merit (FoMs) for the regulating–transient performance. Experimental measurements validate its suitability for the target application, paving the way towards the future achievement of a truly portable System on Chip (SoC) platform for impedance sensors.

Transient-enhanced output-capacitorless CMOS LDO regulator for battery-operated systems

This paper presents a low-power fully integrated 0.18 μm CMOS Low-Dropout (LDO) Voltage Regulator for battery-operated portable devices. A single stage high-gain telescopic cascode-compensated amplifier is used to attain good static performances, while thanks to a very simple dynamic bias circuit, transient performances are significantly enhanced with no quiescent current penalty. Results validate a 1.8 V output voltage from a 3.6 V to 1.9 V battery input voltage, delivering a load current of 50 mA over a 100 pF load. The quiescent current is only 7 μΑ, the line and load regulation are respectively 0.159 mV/V and 0.017 mV/mA, and settling times are lower than 4.6 μs at full load transient.

A power efficient LDO regulator for portable CMOS SoC measurement systems

A 0.18 μm CMOS Low-Dropout (LDO) Voltage Regulator is proposed in this paper for battery-operated measurement systems. With a quiescent current of only 7 μA, it supplies a 1.8 V output voltage from a 3.6 V to 1.9 V battery input voltage, featuring a line regulation of 0.00647 mV/V and a load regulation of 0.0024 mV/mA for a load current of 50 mA over a 100 pF load. Further, thanks to the use of a novel dynamic transient enhancement circuit, with no extra bias current and minimal additional hardware, settling times lower than 5 μs are achieved at full load. Thus, it exhibits remarkable steady state and transient performances with very low power consumption, being a very competitive topology suitable for current portable instruments power management systems.

A CMOS low-power widely programmable active RC filter based on a hybrid CS/D network

This paper presents an enhanced digital tuning approach for RC-active direct form circuits. By introducing a combined summing/dividing network for the current that flows from resistors to virtual grounds, an accurate frequency trimming is accomplished bringing out a linear dependence on the digital input code over a wide tuning range. Simulation results of a monolithic 12-bit 1.8 V–0.18 μm CMOS second order filter provide a 11.46-bit effective resolution to linearly control the frequency over three decades with distortion levels better than −70 dB for 1.5 Vp-p. The power consumption is below 0.5 mW with an active area of 0.087 mm2, which makes it suitable for battery-operated on-chip systems.

An all-MOS low-power fast-transient 1.2 V LDO regulator

This paper presents a fully integrated low-power 0.18 μm CMOS Low-Dropout (LDO) voltage regulator for battery-operated portable devices. A single stage high-gain folded cascode-compensated amplifier is used to attain good static performances, while thanks to a very simple dynamic bias circuit, transient performances are significantly enhanced. Results validate a 1.2 V output voltage from a 3.3 V to 1.3 V battery input voltage, delivering a load current of 50 mA over a 50 pF load. The quiescent current is only 5.9 μA, including an all-MOS 0.4 V reference voltage. Settling times are lower than 5.4 μs at full load transient.