US Patent 10396830 Front-end systems with multiple loopbacks and a shared back switch

Apparatus and methods for front-end systems with multiple loopbacks and a shared back switch are provided. In certain configurations, a front-end system includes a first transmit path between a first transmit port and an antenna port, a second transmit path between a second transmit port and the antenna port, a first loopback path from the first transmit path to a receive port, and a second loopback path from the second transmit path to the receive port. The first and second loopback paths operate with a shared back switch to reduce area and/or complexity of the front-end system. Additionally, each loopback path includes a loopback selection switch that operates in combination with the back switch to select that particular loopback path.