TI’s mmWave radar sensors include an internal processor to stabilize the radar front end performance across temperature and process by running calibration routines. The processor also enables the sensor’s functional safety by periodically determining RF/analog performance parameters and detecting functional failures by running monitoring routines. The processor is programmed by TI and is dedicated for RF calibration and functional safety monitoring.

This document describes the various calibration mechanisms available in TI’s mmWave radar sensors and their configurability.

Figure 1-1 illustrates the radar front-end architecture in a TI mmWave radar device. The performance parameters of the RX LNA, IF amplifiers, TX PA, X4 (frequency multiplier), LO distribution buffers, and the clock sources shown all vary with process and temperature.

Figure 1-1 Radar Front-End Architecture in a TI mmWave Device

The purpose of calibrations is illustrated in Figure 1-2 using RX gain and TX power as examples. The gain of the RX LNA and the TX PA vary from device to device due to manufacturing process variations and also across temperature. The purpose of calibration is to ensure the RX gain and output power are maintained as configured by the user despite variations in process and temperature. To achieve this, the internal processor adjusts the mmWave circuit configurations at initialization (to mitigate effects of process variation) and periodically at runtime (to mitigate effects of temperature drifts). Figure 1-2 illustrates how calibration can be used to maintain the RX Gain and TX Power close to the configured settings across temperature drifts. These charts are illustrative and may not reflect actual device performance. Even with these calibrations done across temperature there would be some gain variations between devices, which must be considered in the user application.

Figure 1-2 RX Gain and TX Power With and Without Calibration

These are representative plots on TI's first generation radar devices. Some of the calibrations (for example, the gain and power calibrations) are implemented as adjustments of circuit configurations based on measurement of RF/analog parameters. Other calibrations are implemented as adjustments based on process/temperature look up tables.

To enable functional safety, such as in automotive applications, the monitoring mechanisms in the device can be configured to periodically provide the host processor with RF/analog health and diagnostic information. These mechanisms enable determination of RF/analog performance parameters and detection of failures arising from transistor and interconnect faults in the field. The diagnostic information they provide can also be helpful during development and optimization of designs integrating TI mmWave radar devices.