Boosting the voltage gain of graphene FETs through a differential amplifier scheme with positive feedback

We study a possible circuit solution to overcome the problem of low voltage gain of short-channel graphene FETs. The circuit consists of a fully differential amplifier with a load made of a cross-coupled transistor pair. Starting from the device characteristics obtained from self-consistent ballistic quantum transport simulations, we explore the circuit parameter space and evaluate the amplifier performance in terms of dc voltage gain and voltage gain bandwidth. We show that the dc gain can be effectively improved by the negative differential resistance provided by the cross-coupled pair. Contact resistance is the main obstacle to achieving gain bandwidth products in the terahertz range. Limitations of the proposed amplifier are identified with its poor linearity and relatively large Miller capacitance.Comment: 19 pages, 10 figure

Low voltage, low power, bulk-driven amplifier

The importance of low voltage and low powered electronics is increasing with advances in medical electronics. This branch of electronics specifically requires low voltage and low power to make efficient innovative medical equipment. Low power electronics are also desirable because it conserves energy and power. This paper proposes a design of a differential in - differential our amplifier that uses a bulk-driven differential pair for the input pair. In addition, it also used bulk-driven current mirrors for the tail current sink and the active loads. The bulkdriven technique helps to achieve the low voltage design. 90nm CMOS technology was considered for the design but at the end SIGE 5AM process was chosen as it has low threshold voltage values maintaining good current - voltage characteristics. The software Cadence was used to simulate the design. A layout of the amplifier is out of the scope of this paper. A gain of 14 dB was achieved using a rail-to-rail voltage of 1V (0.5V to -0.5). The power dissipation was 102uW using 5pF capacitive loads. The values of the calculations match the values of the simulations quite well. Some of the differences can be explained by the lack of accurate knowledge of the some of the process parameters for the SIGE 5AM process. Overall, the design achieved its goals and a successful low voltage and low power fully differential amplifier was created with respectable gain. This amplifier can be used as an input stage for an operational amplifier

Constant current source for converting absolute temperatures to analog voltages

Circuit configuration consisting of matched differential amplifier, temperature compensated zener diode, and low pinchoff-voltage field effect transistor provides accurate and stable current supply for temperature sensor devices

New low-level a-c amplifier provides adjustable noise cancellation and automatic temperature compensation

Circuit utilizing a transistorized differential amplifier is developed for biomedical use. This low voltage operating circuit provides adjustable cancellation at the input for unbalanced noise signals, and automatic temperature compensation is accomplished by a single active element across the input-output ends

A 0.18µm CMOS DDCCII for Portable LV-LP Filters

In this paper a current mode very low voltage (LV) (1V) and low power (LP) (21 µW) differential difference second generation current conveyor (CCII) is presented. The circuit is developed by applying the current sensing technique to a fully balanced version of a differential difference amplifier (DDA) so to design a suitable LV LP integrated version of the so-called differential difference CCII (DDCCII). Post-layout results, using a 0.18µm SMIC CMOS technology, have shown good general circuit performances making the proposed circuit suitable for fully integration in battery portable systems as, for examples, fully differential Sallen-Key bandpass filter

A novel fully differential biopotential amplifier with DC suppression

Fully differential amplifiers yield large differential gains and also high common mode rejection ratio (CMRR), provided they do not include any unmatched grounded component. In biopotential measurements, however, the admissible gain of amplification stages located before dc suppression is usually limited by electrode offset voltage, which can saturate amplifier outputs. The standard solution is to first convert the differential input voltage to a single-ended voltage and then implement any other required functions, such as dc suppression and dc level restoring. This approach, however, yields a limited CMRR and may result in a relatively large equivalent input noise. This paper describes a novel fully differential biopotential amplifier based on a fully differential dc-suppression circuit that does not rely on any matched passive components, yet provides large CMRR and fast recovery from dc level transients. The proposed solution is particularly convenient for low supply voltage systems. An example implementation, based on standard low-power op amps and a single 5-V power supply, accepts input offset voltages up to /spl plusmn/500 mV, yields a CMRR of 102dB at 50 Hz, and provides, in accordance with the AAMI EC38 standard, a reset behavior for recovering from overloads or artifactsPeer Reviewe

Low-Power D-Band CMOS Amplifier for Ultrahigh-Speed Wireless Communications

This paper presents a low-power D-Band amplifier suitable for ultrahigh-speed wireless communications. The three-stage fully differential amplifier with capacitive neutralization is fabricated in 40 nm CMOS provided by TSMC. Measurement results show that the D-band amplifier obtains a peak gain of 9.6 dB over a -3 dB bandwidth from 138 GHz to 164.5 GHz. It exhibits an output 1 dB compression point (OP1dB) of 1.5 dbm at the center frequency of 150 GHz. The amplifier consumes a low power of 27.3 mW from a 0.7 V supply voltage while its core occupies a chip area of 0.06 mm2