The BCM4773 is a family of single-frequency GNSS chipsets supporting GPS, GLONASS, BeiDou, and QZSS.
The BCM47734 was not officially announced, but is used in some Apple products:
The BCM4773 was announced on 10 Sep 2014 in PR Newswire and in GPSWorld.
It was used in the Samsung Galaxy S6 (Exynos), visible in teardowns on iFixit and TechInsights.