[Editor's Note] Motion sensors detect the movement of objects. Recently, they have evolved beyond simple reactions to recognize even subtle human facial expressions, and are used in diverse fields such as home appliances, video, and industry. These motion sensors come in various types, including ultrasonic, laser, and microwave, and can measure distances to objects or speeds. Recently, the use of 60GHz radar sensors has become widespread for intelligent motion sensing applications such as lighting control, automatic door opening and closing, and security alarms. Accordingly, this magazine has prepared a space to look into specific methods for implementing intelligent motion sensing using Infineon's ' XENSIV™' 60GHz radar sensor 'BGT60LTR11AIP' .

■ Radar Sensor , Introducing Radar Technology into Everyday Life

en/product/sensor/radar-sensors/radar-sensors-for-iot/60ghz-radar/?utm_source=e4ds&utm_medium=referral&utm_campaign=202111_ap_en_pss_pss.ap.rfs.p.radar.2122&utm_content=e4ds&utm_term=korean+">Radar sensors are adding 'smartness' to existing motion detection applications and are emerging as a key player in implementing smart life.

Looking at the main applications, it is used in smart home devices such as thermostats, smoke detectors, and smart speakers, and in the smart building field, it is used in contactless switches, occupancy and proximity sensors, etc.




In the smart home appliance sector, it is used in vacuum cleaners, kitchen appliances, smart lighting systems, security systems including IP cameras, automatic door openers, and screen-based systems.

In these areas, radar sensors can be integrated into the system to wake it from 'sleep mode', enter sleep mode when no motion is detected for a defined period of time, or enter auto-lock mode. It can also trigger different functions depending on motion or the direction of motion detection.

Additionally, the high level of integration eliminates the need for complex antenna design, RF expertise, or radar signal processing, and allows transmission and reception through non-metallic materials, allowing them to be concealed within products, bringing radar technology into everyday spaces.

■ 'XENSIV™' 60GHz radar sensor 'BGT60LTR11AIP' , capable of autonomous operation, detecting up to 7m away, and consuming less than 2mW of power The radar sensor that enables these smart functions is Infineon's XENSIV™ 60GHz radar sensor 'BGT60LTR11AIP' .

This sensor is a Doppler motion sensor operating in the 60 GHz ISM (Industrial Scientific and Medical) band and is a radar solution provided in a single package. It is capable of autonomous operation, can detect people at a distance of up to 7 m, and consumes less than 2 mW of power.

The BGT60LTR1AIP is a fully integrated microwave motion sensor with an antenna in the package (AIP) and built-in detectors for motion and motion direction, with a state machine that allows operation of the sensor without an external microcontroller.

The BGT60LTR1AIP is designed as a low-power Doppler radar sensor operating in the 60 GHz ISM-band1.

Key specifications include: △3.3 x 6.7 x 0.56 mm package size △1Tx 1Rx antenna in 80° half-output beam width package (AIP) △Built-in motion detector △Built-in direction of motion detector △Includes multiple operating modes. Fully autonomous mode △Adjustable performance parameters: detection sensitivity, operating time and frequency △FR4 material for PCB design, etc.

Additionally, the autonomous mode has a detection range of up to 7 m, power consumption of less than 2 mW, a detection range of up to 10 m (SPI mode), and advanced features through SPI configuration or signal processing.

Additionally, there are four quad-state (QS1-4) input pins, providing flexibility in performance parameters even when running in autonomous mode.

In SPI mode (selected via the QS1 pin), raw radar data can be extracted from the BGT60LTR1AIP for signal processing on a PC or external MCU, and this sampled radar data can be used to develop custom algorithms.

■ 2 antennas with a beam width of 80°, maximizing coverage





The figure above is a functional block diagram of the BGT60LTR11AIP monolithic microwave integrated circuit (MMIC). This MMIC package includes one transmit and one receive broadbeam antenna. The two antennas have horizontal and vertical half-power beamwidths of 80°, maximizing coverage.

Looking at the block diagram, a voltage-controlled oscillator (VCO) generates a 60 GHz radar signal, which is stabilized using a phase-locked loop (PLL). The transmit signal chain includes an intermediate power amplifier with adjustable output power, which can be controlled via SPI. The power detector monitors the transmit power.

The BGT60LTR11AIP MMIC includes a low-noise quadrature receiver and a low-noise amplifier, which are connected to a quadrature homodyne downconversion mixer. This ensures excellent sensitivity. An RC polyphase filter, receiving the internal VCO signal, generates a quadrature local oscillator signal for the quadrature mixer.

The analog baseband consists of a sample-and-hold circuit for low-power duty cycle operation, followed by an externally configurable high-pass filter, variable gain amplifier (VGA), and low-pass filter.

Target detectors are analog comparators that generate pulses based on target movement in front of the radar. These detectors provide two digital output signals: one indicating the target's movement, and the other indicating the target's direction of movement, such as approaching or receding.

The detector circuit is highly flexible with user-configurable hold times, hit counters, and detection thresholds, reducing the possibility of false detection. Hold time refers to the time that the detector output is maintained after detecting a target, and hit counter refers to the number of comparator output pulses required to determine a valid target detection.