Programmable Current Mirrors Research Articles

Assessment of Two-Dimensional Materials-Based Technology for Analog Neural Networks

Embedding advanced cognitive capabilities in battery-constrained edge devices requires specialized hardware with new circuit architecture and – in the medium/long term - new device technology. We evaluate the potential of recently investigated devices based on 2D materials for the realization of analog deep neural networks, by comparing the performance of neural networks based on the same circuit architecture using three different device technologies for transistors and analog memories. As a reference result, it is included in the comparison also an implementation on a standard 0.18 μm CMOS technology. Our architecture of choice makes use of current-mode analog vector-matrix multipliers based on programmable current mirrors consisting of transistors and floating-gate non-volatile memories. We consider experimentally demonstrated transistors and memories based on a monolayer Molibdenum Disulfide channel and ideal devices based on heterostructures of multilayer-monolayer PtSe2. Following a consistent methodology for device-circuit co-design and optimization, we estimate layout area, energy efficiency and throughput as a function of the equivalent number of bits (ENOB), which is strictly correlated to classification accuracy. System-level tradeoffs are apparent: for a small ENOB experimental MoS2 floating-gate devices are already very promising; in our comparison a larger ENOB (7 bits) is only achieved with CMOS, signaling the necessity to improve linearity and electrostatics of devices with 2D materials.

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El presente trabajo propone una técnica para diseñar, a partir de elementos altamente resistivos, circuitos integrados CMOS analógicos tales como amplificadores compensados en offset, filtros sintonizables de baja frecuencia, espejos de corriente programables y generadores de funciones de membresía. La técnica propuesta incorpora transistores operando en la región de inversión débil para reducir los requerimientos de área y las contribuciones de offset, así como para reducir las componentes de ruido y distorsión, mejorando el compromiso exactitud-velocidad-potencia. Éstas características permiten facilitar el acondicionamiento de señales de baja frecuencia y habilitar el diseño de dispositivos con sintonización multidécada de ganancia y frecuencia. Por otro lado, los circuitos propuestos son atractivos para la implementación analógica de arquitecturas reservadas al ámbito digital, tales como filtros adaptables y sistemas difusos, por mencionar algunos, así como dispositivos de procesamiento y acondicionamiento de señal de alta eficiencia. Se reportan caracterizaciones a partir de simulaciones, mediciones y análisis estadísticos de prototipos diseñados con una tecnología CMOS de 0.5m de largo de canal, dos capas de polisilicio y tres capas de metal. Los resultados obtenidos concuerdan con aquellos anticipados en el diseño de los circuitos.

Circuit implementation of a fully programmable and continuously slope tunable triangular/trapezoidal membership function generator

In this article, a fully programmable membership function generator (MFG) is proposed. This MFG is capable of generating triangular, trapezoidal as well as both S-shaped and Z-shaped membership functions simultaneously. Utilizing a differential pair as an analog switch leads to relax the design of fuzzy systems control part. This MFG has the ability of adapting itself with various fuzzy controllers which produce different control voltage ranges. Unlike the available reported literatures, this MFG uses a new analog programmable current mirror (APCM) instead of digitally programmable current mirrors to adjust the slopes of membership functions. Extensive time domain simulations have been carried out using Hspice by level 49 parameters (BSIM3v3) in standard CMOS technology to validate the effective performance of the proposed MFG.

Programmable feedforward linearized CMOS OTA for fully differential continuous‐time filter design

AbstractIn this paper, a feedforward linearization method for programmable CMOS operational transconductance amplifier (OTA) is described. The proposed circuit technique is developed using simple source‐coupled differential pair transconductors, a feedback‐loop amplifier for self‐adjusting transcoductance (gm) and a linear reference resistor (R). As a result, an efficient linearization of a transfer characteristic of the OTA is obtained. SPICE simulations show that for 0.35µm AMS CMOS process with a single +3V power supply, total harmonic distortion at 1 Vpp and temperature range from −30 to +90°C is less than −49.3 dB in comparison with −35.8 dB without linearization. Moreover, the input voltage range of linear operation is increased. Power consumption of the linearized OTA circuit is 0.86 mW. Finally, the OTA is used to design a third‐order elliptic low‐pass filter in high‐frequency range. The cut‐off frequency of the operational transconductance amplifier‐capacitor (OTA‐C) filter is tunable in the range of 322.6 kHz–10 MHz using the feedforward linearized OTAs with the digitally programmable current mirrors. Copyright © 2009 John Wiley & Sons, Ltd.

Highly linear programmable balanced current scaling technique in moderate inversion

A technique to achieve highly linear current scaling in CMOS technologies is proposed. It is based on two balanced electronically programmable current mirrors operating in moderate inversion. The scaling factor can be continuously adjusted in a wide range. This technique can be employed to achieve or to extend gain adjustment in amplifiers. As an application example, a variable-gain differential current amplifier and a tunable transconductor are presented. Measurement results of the transconductor implemented in a 0.5-/spl mu/m CMOS technology validate in silicon the proposed approach.

Highly linear wide input range CMOS OTA architectures operating in subthreshold and strong inversion

A very low distortion low-voltage CMOS OTA with very wide g m adjustment and input range is presented. It is based on a fixed gain novel highly linear voltage-to-current conversion input stage and uses electronically programmable current mirrors to achieve very wide transconductance gain adjustment range. The OTA input range remains approximately constant with g m adjustment. Bandwidth and input signal range can be adjusted independent of g m. Simulations results in 0.5 μm CMOS technology with ±1 V supplies and 1 V input range are presented which confirm the characteristics of the proposed structure.

Gain programmable current mirrors based on current steering

A new and compact scheme for a programmable current mirror is introduced. It features linear gain continuously adjustable in a wide range. In such a scheme differential pairs are used as current steering elements in order to provide gain programmability. All mirror transistors operate in strong inversion. Implementation of a linear OTA/multiplier is discussed. Experimental verification of the proposed scheme is provided.

A CMOS transconductor with multidecade tuning using balanced current scaling in moderate inversion

A versatile CMOS transconductor is proposed. Voltage-to-current conversion employs a polysilicon resistor and features high linearity over a wide input range and high current efficiency. Programmable balanced current mirrors able to operate in weak or moderate inversion regions provide wide transconductance gain tuning range without degrading other performance parameters like input range and linearity. The transconductor has two degrees of freedom for gain tuning. A 0.5-/spl mu/m implementation achieves a SFDR of 68 dB and a THD of -66.5dB using a dual supply of /spl plusmn/1.3 V with differential input swings equal to 77% of the total supply voltage, transconductance tuning over two decades, and 1.7 mW of static power consumption. Measurements demonstrate that operation in moderate inversion can lead to much less distortion levels than in strong inversion.

Low-voltage wide gm adjustable range highly linear BiCMOS OTA

A low distortion low-voltage BiCMOS OTA with wide gm adjustment range and constant input range is presented. It is based on a highly linear voltage-to-current converter input stage merged with translinear loops that implement linear electronically programmable current mirrors. Experimental results are provided that confirm the characteristics of the proposed OTA with a single 1.7V supply, 1.2V input range, two decades gain adjustment range, and 0.3% THD.

Wide range gain programmable class AB linear current mirrors for low supply operation

Class AB wide range programmable linear current mirrors in bipolar and CMOS technology are presented. Bipolar mirrors can operate with /spl plusmn/0.75 V supplies, CMOS mirrors with /spl plusmn/1.5 V supplies. They are characterized by having an approximately constant bandwidth that is independent of the gain adjustment. Experimental and simulation results are shown that verify the proposed structures.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>