A sub-1 V, 26 μw, low-output-impedance CMOS bandgap reference with a low dropout or source follower mode

We present a low-power bandgap reference (BGR), functional from sub-1 V to 5 V supply voltage with either a low dropout (LDO) regulator or source follower (SF) output stage, denoted as the LDO or SF mode, in a 0.5-μm standard digital CMOS process with V tn≈ 0.6 V and |V tp| ≈ 0.7 V at 27 °C. Both modes operate at sub-1 V under zero load with a power consumption of around 26 μW. At 1 V (1.1 V) supply, the LDO (SF) mode provides an output current up to 1.1 mA (0.35 mA), a load regulation of ±8.5 mV/mA (±33 mV/mA) with approximately 10 μ s transient, a line regulation of ±4.2 mV/V (±50μV/V), and a temperature compensated reference voltage of 0.228 V (0.235 V) with a temperature coefficient around 34 ppm/° C from -20°C to 120 °C. At 1.5 V supply, the LDO (SF) mode can further drive up to 9.6 mA (3.2 mA) before the reference voltage falls to 90% of its nominal value. Such low-supply-voltage and high-current-driving BGR in standard digital CMOS processes is highly useful in portable and switching applications. © 2010 IEEE.published_or_final_versio

A 0.9V 2.7μW small-area 100μs+ analog CMOS tunable-delay circuit utilizing miller effect

We report a novel analog delay circuit based on Miller effect that features small die area and tunable delay in the order of 100μs, without using any external component. The delay time can be tuned by varying the biasing current, capacitor sizes, transconductance of the gain-stage transistor and the corresponding output impedances. The turn-on threshold of the delay circuit can also be raised, as required in some applications, by utilizing the body effect of the input transistors. The circuit has a very low startup voltage (≈0.9V) and consumes a very low power (≈2.7μW) in a standard 1 μm pure CMOS process with Vtn ≈ 0.65V and Vtp ≈ 0.8V at 25°C. Circuit operations are elaborated and its function is verified by simulation and silicon measurement. © 2008 IEEE.link_to_subscribed_fulltex

A 30 μ W CMOS bandgap reference featuring a 1.5-6 mA output driving current and a Miller-effect startup circuit

We present a pure CMOS bandgap voltage reference with a low quiescent current and high output current driving capability. The circuit sources a driving current of up to 1.5 mA with the reference voltage kept above 98.5% of its designated 1.2 V, and up to 6 mA before the voltage drops to 90%. The circuit achieves a very low supply current of 13 μ A, a low power of 30 μ W, a line regulation of ± 2.5 mV / V and a load regulation of ± 7 mV / mA. The reference is implemented in a 1 μ m pure CMOS process with Vtn ≈ | Vtp | ≈ 0.7 V at 25 {ring operator} C using substrate pnp. A startup circuit, which shuts down itself after a controlled delay using Miller effect, is also introduced. By utilizing the body effect of the input transistors, the turn-on threshold of the startup circuit is raised to about 1 V, making it a perfect match for the reference architecture. Silicon measurements are in good agreement with simulations. © 2009 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex

An efficient transfer-function-based approach for the fast tuning and design of DC-DC converters

This paper presents an effective approach for designing switch mode power supply (SMPS) based on simple transfer functions. Empirical system loop gains for trailing-edge modulation voltage-mode and current-mode buck, boost, and buck-boost converters are listed and verified by laboratory measurement. The method allows practitioners to design DC-DC power converters in an efficient and systematic manner using Type-I, II, or III internal compensation circuitry. The contribution and trade-off of specific components to the system dynamics of a converter is easily captured in the proposed framework. An example demonstrating the optimized design of a stable boost converter is also elaborated. © 2007 IEEE.link_to_subscribed_fulltex

A low-power high-output-driving CMOS voltage reference with ±0.5% trimming accuracy

We present a CMOS bandgap voltage reference with a low quiescent current and high output current driving capability of up to 1.5mA. The circuit achieves a very low supply current of 11μA, a low power of 27μW, a line regulation of ±2.5mV/V and a load regulation of 14mV/mA. The bandgap reference is implemented in a 1μm pure CMOS process with Vthn ≈ |V thp| ≈ 0.9V at 25°C. Experimental results show the silicon measurements are in good agreement with simulations. The proposed reference circuit constitutes a versatile solution in switching mode power supply (SMPS) and portable applications, due to its driving capability and low power consumption. © 2007 IEEE.link_to_subscribed_fulltex

A low-power high-output-driving CMOS voltage reference with ±0.5% trimming accuracy

We present a CMOS bandgap voltage reference with a low quiescent current and high output current driving capability of up to 1.5mA. The circuit achieves a very low supply current of 11μA, a low power of 27μW, a line regulation of ±2.5mV/V and a load regulation of 14mV/mA. The bandgap reference is implemented in a 1μm pure CMOS process with Vthn ≈ |V thp| ≈ 0.9V at 25°C. Experimental results show the silicon measurements are in good agreement with simulations. The proposed reference circuit constitutes a versatile solution in switching mode power supply (SMPS) and portable applications, due to its driving capability and low power consumption. © 2007 IEEE.link_to_subscribed_fulltex

Randomized evaluation of the audiologic outcome of ventilation tube insertion for middle ear effusion in patients with nasopharyngeal carcinoma

Objective: Complications after ventilation tube insertion for middle ear effusion in patients with nasopharyngeal carcinoma are frequent. This may compromise the overall benefit obtained from the procedure. This study evaluates the hearing improvement after tube insertion compared with observation alone to see if the benefits of the procedure outweigh its potential complications. Design: Prospective randomized controlled trial. Setting: Full clinical and emergency otolaryngologic services hospital in an academic institution. Methods: Patients with nasopharyngeal carcinoma and middle ear effusion were randomized for preradiotherapy ventilation tube insertion or observation. Audiologic assessment with a pure-tone audiogram was performed before the procedure, after ventilation tube insertion, and at fixed intervals after irradiation. Audiologic outcome was compared between the two groups. Main Outcome Measure: Air-conduction threshold and air-bone gap on a pure-tone audiogram at different intervals after radiotherapy. Results: There was no significant difference in hearing threshold changes between the two groups for up to 4 years. Both groups had air-bone gap improvement following radiotherapy and the improvement was not significantly different between the two groups. The proportion of patients with closure of the air-bone gap on follow-up was not different between the two groups. Conclusions: Ventilation tube insertion before radiotherapy did not offer additional hearing benefit when compared with observation alone. The procedure had no deleterious effect on hearing for up to 4 years.link_to_subscribed_fulltex

Long-term sensorineural hearing deficit following radiotherapy in patients suffering from nasopharyngeal carcinoma: A prospective study

Background. This was a prospective study to evaluate the effect of radical external irradiation on inner ear function after treatment of nasopharyngeal carcinoma. Methods. Pure tone audiograms were performed at regular intervals before, after, and up to 4.5 years following completion of radiotherapy. Results. Two hundred ninety-four patients (526 ears) were included. Within 3 months after radiotherapy, deterioration of bone conduction threshold at 4 kHz and pure tone average (average of 0.5 kHz, 1 kHz, and 2 kHz) were noted in 164 ears (31%) and 75 ears (14%), respectively. Patients older than 50 years and ears with threshold below 60 dB at 4 kHz before radiotherapy were significant factors (p < 0.01 and p < 0.001) associated with a 4 kHz loss. In 40% of these ears, recovery was evident at 2 years. With follow-up for 4.5 years, the probability of significant threshold deterioration increased with time. Conclusion. Sensorineural hearing loss started soon after radiotherapy. Early changes could be reversible while the probability of persistent hearing loss continued to increase.link_to_subscribed_fulltex

Sensorineural hearing loss in patients treated for nasopharyngeal carcinoma: A prospective study of the effect of radiation and cisplatin treatment

Purpose: The pattern of sensorineural hearing loss (SNHL) after primary treatment for nasopharyngeal carcinoma (NPC) was studied, and the effect of cisplatin, radiotherapy dose, and fractionation were evaluated. Methods and Materials: One hundred thirty-two patients, 227 ears, and 1100 audiogram reports were analyzed. Radiotherapy dose ranged from 59.5 to 76.5 Gy. Fifty- two patients received preirradiation cisplatin, total dose 100-185 mg/m 2. Serial postirradiation bone conduction thresholds at 0.5 kHz, 1 kHz, 2 kHz, and 4 kHz were compared with pretreatment thresholds at respective frequencies. Increase of at least 15 dB was considered as significant and was further grouped as transient or persistent SNHL. Univariate and multivariate analyses were performed to identify predicting factors for persistent SNHL. Results: At median follow-up of 30 months, 24.2% of ears developed persistent SNHL. High frequency was more affected than low frequencies, 22 vs. 5.3%. Males were more affected than females, 29.4 vs. 15.5%, p = 0.0132. Incidence of persistent SNHL increased with age, with 0, 17.2, and 37.4% of patients aged under 30, between 30-50 and over 50 affected, respectively, p = 0.0001. High incidence was found in patient with postirradiation serous otitis media (SOM), 46.9%. Chemotherapy with cisplatin and radiation dose or fractionation had no significant effect. Multivariate analysis confirmed age, sex, and postirradiation SOM as significant prognostic factors for persistent SNHL. Conclusions: Transient and persistent SNHL occurred after radiotherapy, more commonly affecting high frequency. A low dose of preirradiation cisplatin did not increase the risk. A dose fractionation effect of radiotherapy was not confirmed in this study.link_to_subscribed_fulltex