2 The importance of integration

One of the parameters to ensure accurate and repeatable measurements in FMCW systems is the chirp ramp linearity. Having the full analog chain integrated on a monolithic microwave integrated circuit not only decreases design-to-design variations, but also helps increase overall measurement linearity, since it is possible to perform effective monitoring and calibration over age and temperature.

Looking at the block diagram of the Texas Instruments (TI) IWR6843 in Figure 2-1, you can see that the only external component for the transmitter-receiver section is a standard 40-MHz crystal. Besides this external 40-MHz crystal, the IWR6843 offers full transmitter-receiver integration, with:

• A ramp generator.
• A fractional phase-locked loop.
• A 20-GHz voltage-controlled oscillator (VCO), which when routed externally (or selected from an external source) can synchronize multiple front ends and enable coherent sampling on much larger virtual antennas.

The IWR6843 also includes the full radio-frequency (RF) chain for the transmitter and receiver, including:

• A software-programmable power amplifier that enables multiple levels of transmit power to allow maximum flexibility when adapting the link budget to the environment and RF regulations.
• Dynamically programmable phase shifters for beamsteering.
• A low-noise amplifier, which when programmed in conjunction with power amplifiers enables link budget fine-tuning.
• Mixers thatl generate an intermediate frequency (IF) from the transmit and receive chirps.
• IF analog filters.
• Analog-to-digital converters (ADCs) with up to a 25-MHz sampling frequency.

Having the full RF chain integrated on the MMIC system-on-a-chip enables a level of diagnostics capability required for functional safety.

Fully digital signal-chain processing integration on the IWR6843 offers:

• A radar hardware accelerator that supports 16-bit range, Doppler or angle-of-arrival fast Fourier transform (FFT), and a constant false alarm rate (CFAR) among classical radar signal processing.
• A 600-MHz fully programmable digital signal processor to enable fully customizable signal processing.
• A fully programmable 200-MHz Arm® Cortex®-R4F microcontroller for clustering, tracking and application-level code.

Besides the die-level integration, a variant of the IWR6843, the IWR6843AOP, comes with antennas on the package, bringing further integration and reducing the printed circuit board (PCB) area for space-constrained applications or when PCB routing of RF signals is challenging.