OL2385 datasheet(21/85 Pages) NXP

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OL2385

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Product data sheet

COMPANY PUBLIC

Rev. 1.0 — 15 June 2016

21 of 85

NXP Semiconductors

OL2385

Industrial RF transceiver

input with a wide-band input matching optimized for 200Ohms. A current reuse scheme is

employed to maintain maximum performance with minimum current consumption. Power

consumption is controllable depending on the demands of the system. The advanced

feedback structure in combination with the attenuator set-up results in very low LO

radiation.

9.5.4 Attenuators

Passive 2dB step attenuators are positioned in front of the LNA and in front of the mixer in

order to control the gain of the receiver. The RF inputs have integrated ESD protection

and integrated AC coupling for easy application. A matching network can be applied

off-chip for best performance and adaptation to different source impedances.

9.5.5 Mixer

The mixer multiplies the single-ended RF signal with a balanced quadrature (I and Q) LO

signal in order to differentiate between the wanted and image channel. A special algorithm

is used to remove the impact of analog mismatch on the image rejection. This usually

leads to intrusion (leakage) of the image channel into the wanted channel.

9.5.6 Baseband amplifier (TIA) and DC offset compensation

The baseband amplifier stage (TIA - transimpedance amplifier) amplifies the balanced

quadrature (I and Q) mixer output signals to the optimal level for the ADC and performs

the anti-aliasing filtering in front of the sigma-delta ADC. Internal DC offset correction

loops guarantee maximum image suppression and high linearity and dynamic range.

9.5.7 SD ADC

The SD ADC is a 1-bit higher order oversampled sigma-delta ADC with very low current

consumption. The sigma delta switched time core makes use of the most modern

feedback techniques to ensure stability and performance over a wide frequency band,

process and temperature variation. It features fast auto-calibration for optimum

performance. The calibration time is typically below 1 µs. The output is a single bit

data-stream which is further processed by the digital baseband.

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