When to use ADC noise for small signals?

When to use ADC noise for small signals?

The level of ADC noise contribution for small-signal inputs is used for signals near and just above the receiver sensitivity. Refer to Figure 1 and use the following steps to approximate the ADC effective noise figure for small-signal analog input levels: Calculate the ADC’s full-scale level (in dBm).

How is the ADC noise calculated in CDMA?

The ADC noise in the 1.23MHz CDMA channel bandwidth is 15.1dB lower than the noise in the first Nyquist region due to the processing gain achieved. All noise power in Figure 4 is calculated in the channel bandwidth unless otherwise specified. An overall gain of 35dB is calculated to achieve the desired typical noise figure value of 3.7dB.

Is the code transition noise finite in ADC?

A practical ADC has a certain amount of code transition noise, and therefore a finite transition region width. Figure 1b shows a situation where the width of the code transition noise is approximately one least-significant bit (LSB) peak-to-peak.

What are the limitations of a high speed ADC?

Two fundamental limitations to maximizing SFDR in a high-speed ADC are the distortion produced by the front-end amplifier and the sample-and-hold circuit; and that produced by nonlinearity in the transfer function of the encoder portion of the ADC. The key to achieving high SFDR is to minimize both sources of nonlinearity.

How is thermal noise reduced in an ADC converter?

Although the thermal noise bandwidth is usually on the order of nV per square root of frequency, once the signal is input to an ADC and sampled across the ADC’s bandwidth, you can pass a significant noise signal into the converter, as shown in Fig. 1. This noise can be reduced by oversampling.

How is quantization noise related to the ADC?

quantization “noise” actually appears as an offset error in the ADC output. Finally, an obvious but important result of quantization noise is that the ADC cannot measure beyond its resolution, as it cannot distinguish between sub-LSB changes in the input. Unlike quantization noise, which is a byproduct of the