Effective number of bits

About: Effective number of bits is a research topic. Over the lifetime, 3776 publications have been published within this topic receiving 46130 citations.

Exploiting Electrocorticographic Spectral Characteristics for Optimized Signal Chain Design: A 1.08 Analog Front End With Reduced ADC Resolution Requirements

Abstract: Electrocorticography (ECoG) is an important area of research for Brain-Computer Interface (BCI) development. ECoG, along with some other biopotentials, has spectral characteristics that can be exploited for more optimal front-end performance than is achievable with conventional techniques. This paper optimizes noise performance of such a system and discusses an equalization technique that reduces the analog-to-digital converter (ADC) dynamic range requirements and eliminates the need for a variable gain amplifier (VGA). We demonstrate a fabricated prototype in 1p9m 65 nm CMOS that takes advantage of the presented findings to achieve high-fidelity, full-spectrum ECoG recording. It requires 1.08 $\mu{\rm W}$ over a 150 Hz bandwidth for the entire analog front end and only 7 bits of ADC resolution.

Two-stage a-to-d converter

Abstract: A two-stage analog-to-digital converter wherein the first stage is a resistor-string d-to-a converter controlled by a successive-approximation register, functioning in a first phase of the conversion operation to determine a set of higher order bits of the digital output signal The second stage is a dual-slope integrating-type a-to-d converter functioning in a second phase of the conversion operation to determine the remaining lower-order bits of the digital output signal The dual-slope converter receives a reference signal derived from two adjacent junction points of the first-stage resistor-string d-to-a converter corresponding to the higher order bits determined in the first phase of operation, thereby to assure high resolution performance

General purpose system for digitizing an analog signal

Abstract: A general purpose programmable optical analyzer employs a nonlinear gain at the input stage of an analog to digital converter in order to limit the number of bits used to resolve shot noise.

Method of testing an analog-to-digital converter

Abstract: Only the value of the least-significant bit, or of some of the less-significant bits is used in order to test an analog-to-digital converter in an integrated circuit. The information concerning the differential and the integral non-linearity can be determined from the values of said less-significant bit. Furthermore, the functionality of the analog-to-digital converter is tested by counting the number of changes of the least-significant bit and by comparing this number with the value formed by the other bits.

13.10 A >1W 2.2GHz switched-capacitor digital power amplifier with wideband mixed-domain multi-tap FIR filtering of OOB noise floor

Abstract: Digital power amplifiers and transmitters have drawn significant interest in the recent past due to their reconfigurability, compatibility with CMOS technology scaling and DSP, and potential for automated design synthesis [1–5]. While significant progress has been made in achieving moderate output power levels in CMOS, wideband modulation, and high efficiency under back-off, out-of-band emissions remain an unsolved problem. The elimination of the analog reconstruction filter that follows the DAC in a conventional analog transmitter implies that broadband DAC quantization noise appears at the output of the transmitter unfiltered. Quantization noise can be suppressed by increasing resolution and/or sampling rate, but to meet the challenging −150 to −160dBc/Hz out-of-band (OOB and specifically RX-band) noise requirement of FDD with conventional duplexers, nearly 12b at 0.5GS/s is required. Such a high effective number of bits (ENOB) is extremely challenging in digital PAs given their strong output nonlinearity. Consequently, while low-power modulators are able to approach −150dBc/Hz RX-band noise floor and below [6], state-of-the-art digital transmitters achieve −130 to −135dBc/Hz RX-band noise, nearly 20dB or 100× away [2–4]. Embedding mixed-domain FIR filtering into digital transmitters to create notches in the RX band has been proposed [4,7], but, while successful in low-power modulators [7], nonlinearity significantly limits notch depth to <10dB in digital PAs [4]. Further, notch bandwidth (BW) is far less than 20MHz, the typical LTE BW, in the simple two-tap FIR structures that have been explored [4].