Each receiver chain of the AFE77xxD includes a 28-dB range digital step attenuator (DSA), followed by

a wideband passive IQ demodulator, and a baseband amplifier with integrated antialiasing low pass filters

with programmable bandwidth, driving continuous-time sigma-delta ADCs. The RX chain can receive an

instantaneous bandwidth (IBW) up to 200 MHz (AFE77x8D) / 300 MHz (AFE7769D). Each receiver channel

has two analog peak power detectors and various digital power detectors to assist an external or internal

autonomous AGC control for receiver channels, and a RF overload detector for device reliability protection. The

integrated QMC (quadrature mismatch compensation) algorithm is capable to continuously monitor and correct

for the RX chain I and Q imbalance mismatch without the need to inject any specific signals or perform offline

calibration.

Each transmitter chain includes two 14-bit, 3.3-Gsps IQ DACs, followed by a programmable reconstruction and

DAC image rejection filter, an IQ modulator driving a wideband RF amplifier with 39-dB range gain control. The

TX chain integrated QMC and LO leakage cancellation algorithms, leveraging the FB path can constantly track

and correct for the TX chain IQ mismatch and LO leakage.

Each FB path is based on RF sampling architecture, and includes an input RF DSA driving a 14-bit, 3.3-Gsps

RF ADC. The direct sampling architecture provides an inherently wideband receiver chain and simplifies the

calibration of the TX chains impairments. The FB path integrates two independent NCOs, which allow for a fast

switching between two observed RF input bands.

The synthesizer section integrates four fractional-N RF PLLs that can generate four different RF LOs, allowing

the device to support up to two different bands, each one configured as two transmitters, two receivers, and

one feedback path (with AFE7768D/AFE7769D), or one transmitter, one receiver, and one feedback path (with

AFE7728D) .

AFE7768D/AFE7769D Block Diagram

AFE7769D, AFE7728D, AFE7768D

SBASAG3A – JULY 2023 – REVISED OCTOBER 2023

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