US Patent 7466265 GPS receiver with extended hot start capability

A global positioning system (GPS) receiver with extended 1-second hot start capability has an RF chip, a baseband chip, a battery and a LDO regulator. When the GPS receiver is turned on, a main supply voltage charges the battery to store backup power. Once the main supply voltage is turned off, the baseband starts a countdown period. During the countdown period, critical portion of the RF chip, the baseband chip and the regulator use the backup power to continue keeping time. If the GPS receiver is restarted during the countdown period, the GPS receiver has retained information to allow 1-second hot start and the GPS receiver generates position fix instantaneously.