Being a core component of an analog-to-digital converter (ADC), the operational amplifier is expected to provide sufficient DC gain and bandwidth to make the output amplitude less than 1⁄2 Least Significant Bit (LSB) in a half clock cycle. However, due to the limitation of the operational amplifiers in DC gain and bandwidth, most ADC is limited to 10-Bit, 100 Million Samples per Second (MSPS) [...

For low-voltage, low-power circuit design, the linear model for operational amplifiers is insufficient to accurately predict the static and dynamic behavior of the circuit. This paper introduces a nonlinear model for operational amplifiers based on amplifiers’ DC transfer characteristic. By using this nonlinear model, the behavior of an operational amplifier with feedback network can be describ...

In this paper we present a three-stage fully differential operational amplifier in 120nm digital CMOS. To reach high gain gain-boosted cascodes in the first stage are used. The gain-boost amplifiers are realized as two-stage amplifiers with self cascodes. A DC gain of 108dB and an unity-gain frequency of 1.06GHz are achieved at 1.2V supply. The operational amplifier is appropriate for supply vo...

This application report presents a simple power tracking technique for efficiency enhancement in CDMA RF power amplifiers. This technique involves the use of a linear-in-dB RF power detector and a DC-DC converter switch. This enhancement scheme switches the DC supply voltage, VCC, of an RF power amplifier into two different levels through a DC-DC converter. Texas Instruments RF power detector L...

Low-voltage and low-power multistage operational transconductance amplifiers with new and efficient gain boosting and frequency compensation schemes are proposed in this paper. The presented amplifiers are designed to drive large capacitive loads with small power consumption at low-voltage supplies. The compensation schemes exploit a single Miller capacitor and an active feedback to form the ma...

This application note defines the ac specifications of voltage feedback operational amplifiers (Op Amps). Directly following these definitions, related amplifier circuits are given where the ramifications of the particular specifications causes less than optimum circuit performance. This is then followed with appropriate circuit solutions.The companion application note for DC specifications alo...

39 Cortical spreading depolarizations (spreading depressions and peri-infarct 40 depolarizations) are a pathology intrinsic to acute brain injury, generating large negative 41 extracellular slow potential changes (SPCs) which, lasting on the order of minutes, are 42 studied with DC-coupled recordings in animals. The spreading SPCs of depolarization 43 waves are observed in human cortex with AC-...

Cortical spreading depolarizations (spreading depressions and peri-infarct depolarizations) are a pathology intrinsic to acute brain injury, generating large negative extracellular slow potential changes (SPCs) that, lasting on the order of minutes, are studied with DC-coupled recordings in animals. The spreading SPCs of depolarization waves are observed in human cortex with AC-coupled electroc...

A CMOS multistage RF amplifier with DC coupling is presented. A complete optimisation of the various stages is done to maximize the RF gain for a given power budget. To decrease the effects of offsets and tolerances in high gain multistage amplifiers usually (lossy) AC coupling is used. The presented circuit employs DC coupling and DC control circuitry to avoid coupling-induced losses. Compared...