SWITCH TOPOLOGY FOR SWITCHING FILTERS MULTIPLEXERS

摘要

This disclosure relates to radio frequency (RF) front end circuitry used to route RF signals. In one embodiment, the RF front end circuitry has a filter circuit and a switch device. The switch device includes a common port, an RF port, and switchable path connected in series between the common port and the RF port. The switch device is configured to present approximately the filter capacitance of the filter circuit at the common port when the switchable path is closed. However, when the switchable path is open, the switch device is configured to present a device capacitance at the common port that is approximately equal to the filter capacitance of the filter circuit. In this manner, if the common port is connected to an antenna, the capacitance seen by the antenna from the common port remains substantially unchanged regardless of which of the switchable path is opened or closed.

主权项

1. Radio frequency (RF) front end circuitry comprising:
a first filter circuit coupled to a first RF port, wherein the first filter circuit is configured to present a first filter capacitance to the first RF port; and a switch device comprising a common port, the first RF port, a first switchable path operable to be opened and closed and connected in series between the common port and the first RF port, wherein the switch device is configured to:
present approximately the first filter capacitance of the first filter circuit at the common port when the first switchable path is closed; andpresent approximately a first device capacitance at the common port when the first switchable path is open, wherein the first device capacitance approximately equals the first filter capacitance.