MAX186DCPP+ 开发手册 - Maxim Integrated（美信）

Maxim > Design Support > Technical Documents > Application Notes > A/D and D/A Conversion/Sampling Circuits > APP 1108

Keywords: single-ended, signal conditioning, pseudo differential, fully differential, common mode rejection,

CMRR, noise, ADC, a/d, analog digital, analog to digital, converters, convertors

APPLICATION NOTE 1108

Understanding Single-Ended, Pseudo-Differential

and Fully-Differential ADC Inputs

Jun 14, 2002

Abstract: Many of today's instrumentation and process control applications convert the analog output of a

sensor for processing and/or storage using an analog-to-digital converter (ADC). For voltage input ADCs,

For voltage input ADCs, three different input structure types exist: Single-Ended, Pseudo-Differential and

Fully-Differential.

The simplest solution is to select an ADC input structure that matches the sensor output. However, there

are trade-offs with each structure that should be considered. In addition, if signal-conditioning circuitry is

used between the sensor and the ADC, this circuitry can affect the ADC input structure choice. Some

ADCs are configurable, allowing selection between single-ended or pseudo-differential input structures

(MAX186, MAX147) while others allow a choice between single-ended or fully-differential (MAX1298,

MAX1286).

Fully-Differential Inputs

For maximum noise rejection, use fully-differential inputs. Figure 1 shows an example of a fully-

Csample(-) connect together in series, such that the voltage sample presented to the ADC is the

difference of AIN(+) and AIN(-). The differential architecture in conjunction with acceptable input bandwidth

in the T/H are key ingredients for good dynamic common-mode rejection.