Transimpedance Amplifier Topology Research Articles

Exploring Transimpedance Amplifier Topologies: Design Considerations and Trade-Offs

Exploring Transimpedance Amplifier Topologies: Design Considerations and Trade-Offs

A Low-Power High-Sensitivity Photocurrent Sensory Circuit with Capacitive Feedback Transimpedance for Photoplethysmography Sensing.

This study presents an integrated analog front-end (AFE) tailored for photoplethysmography (PPG) sensing. The AFE module introduces a novel transimpedance amplifier (TIA) that incorporates capacitive feedback techniques alongside common drain feedback (CDF) TIA. The unique TIA topology achieves both high gain and high sensitivity while maintaining low power consumption. The resultant PPG sensor module demonstrates impressive specifications, including an input noise current of 4.81 pA/sqrt Hz, a transimpedance gain of 18.43 MΩ, and a power consumption of 68 µW. Furthermore, the sensory system integrates an LED driver featuring automatic light control (ALC), which dynamically adjusts the LED power based on the strength of the received signal. Employing 0.35 µm CMOS technology, the AFE implementation occupies a compact footprint of 1.98 mm × 2.475 mm.

Exploring Transimpedance Amplifier Topologies: Design Considerations and Trade-offs

Exploring Transimpedance Amplifier Topologies: Design Considerations and Trade-offs

A Comparative Analysis of Gain and Bandwidth of CMOS Transimpedance Amplifier

The paper presents the various trans-impedance amplifier (TIA) topologies has been studied and presented with an insight of their Gain and Bandwidth. The device parameters such as gain and bandwidth has been studied and compared for various TIA topologies. The performance of the presented topologies of TIA has been compared and summarized to get an overview. The comparison is done on the basis of its topology and device technology along with gain, bandwidth and power supply. In this paper recent advancement and future scope are also discussed.

A 4 × 4 Biosensor Array With a 42-μW/Channel Multiplexed Current Sensitive Front-End Featuring 137-dB DR and Zeptomolar Sensitivity

This paper presents a multiplexed current sensitive readout for label-free zeptomolar-sensitive detectors realized with large area Electrolyte Gated Organic Thin Film Transistors (EGOFETs). These highly capacitive biosensors are multiplexed using an OTFT line driver and OTFT switches, and interfaced to a 65-nm Si CMOS, low power, pA-sensitive front-end. The Si chip performs analogue-to-digital conversion and data transmission to a microcontroller too. A current domain interface is used to transmit the signals coming from multiple biosensors to the 1.2 V-supply CMOS Si-IC via the 30V-supply OTFT electronics. Exploiting an analogue module implemented in the Si-IC, the EGOFETs are precisely biased, even in presence of a large OTFT multiplexer resistance. The CMOS current sensitive front-end achieves a dynamic range (DR) of 137 dB and a power consumption of 42 lW per channel reaching a state-of-the-art DR-power-bandwidth FOM of 208 dB. The front-end has been designed with a first stage programmable-gain, active-feedback transimpedance amplifier topology that, contrary to common current-sensitive front-end solutions, is not affected by the sensor capacitance. The system has been validated with different concentrations of human IgG and IgM proteins using both a single sensor and a 4x4 array of EGOFETs. Thanks to the multiplexing strategy and the low-costs of its modules, the system here presented has the potential to enable widespread use of precision diagnostic with extreme sensitivity even in point-of-care and low-resource settings.

Ultra-low-noise TIA topology for MEMS gyroscope readout

This paper proposes a TIA topology that can be used in accelerometer and gyroscope systems. The proposed TIA topology considerably relaxes the trade-off among the transimpedance gain, bandwidth, and input referred current noise without increasing the power consumption. Furthermore, this paper presents a model for gyroscope microelectromechanical systems (MEMS) resonator that enables us, unlike prior works, to predict the resolution of the gyroscope system at the early stage of the design. In this model, the noise arising from driving loop blocks is compared with the noise of sense channel blocks. It has been illuminated that the noise of sense transimpedance amplifier (TIA) is the most influential in the resolution of the gyroscope system. To improve the resolution, the proposed TIA is employed in the sense channel of the gyroscope system. It enhances the resolution by about 57% compared with the conventional TIA employed in the sense channel. Measurement results of a discrete-element prototype also verify the performance improvement of the proposed TIA topology.

CMOS Transimpedance Amplifiers for Biomedical Applications: A Comparative Study

Recently, different medical devices have emerged and utilized in a numerous health care fields such as pulse oximetry, cuffless blood pressure using Photoplethysmogram (PPG), noninvasive blood glucose measuring, and Near Infrared Spectroscopy (NIRS). Those devices are very similar in their analog front end circuit which is a transimpedance amplifier (TIA). Many different TIA topologies have appeared in different optoelectronic fields which make the choice of the best TIA topology for a certain application a challenging task. In this regard, this paper presents a comparison between state of the art, previously published TIA topologies. All topologies are simulated at four different simulation cases to account for various design scenarios. The topologies are simulated with 10 pF photodiode (PD) input capacitance and 5 KHz bandwidth (BW) while optimizing for two different targets; one time for minimum input noise and the other for minimum power consumption. Moreover, the same procedures are performed with 2 pF PD and 100 MHz BW to account for higher BW demanding applications. The studied topologies are compared according to their transimpedance gain, power consumption, total input referred noise current, and dynamic range (DR) to expose their relative merits. A noise and a transimpedance gain mathematical models are also presented for each topology to assist the comparison. Recommendations to designers on which TIA to select in a certain application are concluded according to the obtained results.

A Sub-µg Bias-Instability MEMS Oscillating Accelerometer With an Ultra-Low-Noise Read-Out Circuit in CMOS

This paper describes a SOI MEMS oscillating accelerometer with a fully differential CMOS continuous-time read-out circuit. A new ultra-low-noise continuous-time bandpass transimpedance amplifier (TIA) is proposed and serves as the front-end of the read-out circuit. The new TIA topology greatly relaxes the tradeoffs among gain, bandwidth and noise, and achieves a state-of-the-art input referred current noise density of 6.6 fA/ $\sqrt {\hbox{Hz}} $ , which helps improve the bias-instability and noise floor of the MEMS oscillating accelerometer. The TIA provides a transimpedance gain of 45 MΩ in the bandwidth from 0.5 Hz to 350 kHz and consumes only 583 µW. To reduce the amplitude-stiffness effect induced frequency variation, the accelerometer employs a displacement control strategy that stabilizes the oscillation amplitude of the MEMS oscillator and a chopper stabilization technique to minimize the flicker noise in the amplitude control block. The accelerometer yields bias-instability of 0.6 µg (Allan Variance) or bias stability of 6.3 µg (1σ in one hour) and 2 µg/ $\sqrt{\hbox{Hz}}$ noise floor with 140 Hz/g scale factor and ±20 g full scale. The overall power consumption of the accelerometer is 3.5 mW under a 1.5 V supply.

The Transimpedance Limit

The transimpedance limit describes the maximum transimpedance that a transimpedance amplifier (TIA) can attain for a given bandwidth and technology. We analyze and compare this limit for a wide variety of TIA topologies thus exposing their relative merits. The topologies considered are the shunt-feedback TIA with single and multistage amplifier, the shunt-feedback TIA with feedback capacitor, the shunt-feedback TIA followed by a post amplifier, the shunt-feedback TIA with a current amplifier, the common-base/gate feedforward TIA, the shunt-feedback TIA with a common-base/gate input stage, and the shunt-feedback TIA with a regulated-cascode input stage. The analysis includes a discussion of the conditions under which the limit is realizable.

A 10-GHz bandwidth pseudomorphic GaAs/InGaAs/AlGaAs MODFET-based OEIC receiver

Summary form only given. High-performance quarter-micrometer pseudomorphic modulation-doped field-effect transistors (MODFETs) and a metal-semiconductor-metal (MSM) photodetector have been used in the design of a 0.85- mu m wavelength sensitive high-speed OEIC (optoelectronic integrated circuit) lightwave receiver. The receiver circuit utilizes a transimpedance amplifier topology with all active components including a variable active feedback resistor consisting of a common-gate FET. Discrete MODFETs with -0.7-V thresholds exhibit transconductances of over 500 mS/mm and f/sub T/s of approximately 70 GHz. Receiver transimpedance gains (Z/sub T/) from 200 to 1500 Omega are obtained by varying the active feedback resistor. An amplifier 3-dB analog bandwidth of 10 GHz is measured with a maximally flat Z/sub T/ response of 300 Omega , resulting in a transimpedance-bandwidth product of 3 THz- Omega . The receiver frequency response, deduced from optical pulse measurements, confirms a 10-GHz bandwidth and indicates that the receiver is suitable for unequalized 18-Gb/s NRZ communications. >