Infineon BGT24LTR11 User Manual page 15

User's guide to BGT24LTR11
XENSIV™ 24 GHz radar MMIC
Table of contents
There are two reasons for toggling VCC and VCC_PTAT:
Turning off VCC and VCC_PTAT reduces current consumption (45 mA and 1.5mA, respectively)
•
The PTAT source generates noise at its output when running, and this noise on the tuning voltage will
•
degrade the signal-to-noise ratio (SNR) of the system. However, for some short range this SNR might still be
acceptable.
Operation:
1. TX_ON = 0 V. Disables TX output to prevent out of band emissions.
2. Vctrl = 3.3 V. This turns on the PTAT source (VCC_PTAT = 3.3 V) while VCC line for the entire RF stage
including the VCO is disconnected from the power supply.
3. Wait for C5 to be charged. At the start-up of the system when the capacitor is fully discharged, this will
require a longer time. During normal operation, the capacitor is only slightly discharged and will be very
quickly recharged.
4. Vctrl = 0 V. Turn off PTAT and turn on the rest of the chip (RF with VCO).
5. Wait for VCO to settle its frequency. Settling time of the VCO is maximum 100 ns.
6. TX_ON = 3.3 V. Enables TX output.
TX_ON should be delayed by about 200ns vs. RF section ON (Vctrl = 0 V) to keep TX signal clean.
7. Sample IF frequency.
8. Go to 1.
Further reduction of the power consumption is possible by introducing a time frame when both VCC and
VCC_PTAT are disconnected. This would mean that VCC_PTAT needs to be disconnected from Vctrl and one
more independent GPIO pin needs to be available at the microcontroller unit (MCU) in the system.
Application note 15 Revision 1.50
2023-02-14