Abstract: A biasing circuit is described for a radio frequency (RF) amplifier that provides a stable signal source. The described bias circuit has two or more transistors coupled in at least one feedback loop, with a buffering transistor providing the output biasing signal and buffering the feedback loops from the output of the of the biasing circuit. This arrangement provides thermal compensation, reduces fluctuations in the feedback loops that stabilize the biasing circuit, and allows for higher biasing current demand.

Abstract: An RF switching circuit that incorporates a film bulk acoustic resonator (FBAR) device and one or more capacitors that are used to vary the capacitance of the FBAR device to change the frequency range that is blocked by the FBAR device. When the RF switching circuit is in a first switching state, a first set of RF signals in a first frequency range is blocked by the RF switching circuit while RF signals of other frequencies are passed by the RF switching circuit. When the RF switching circuit is in a second switching state, a second set of RF signals in a second frequency range is blocked by the RF switching circuit while RF signals of other frequencies are passed by the RF switching circuit.

Abstract: A low noise amplifier and method for amplifying an input signal uses a high impedance electrical element having both inductance and capacitance connected between an output transistor and a bias circuit to provide noise isolation between the bias circuit and the output transistor. The noise isolation provided by the high impedance electrical element reduces the amount of bias circuit noise introduced into the output signal. In an embodiment, the high impedance electrical element includes an inductor and a capacitor connected in parallel. In another embodiment, the high impedance electrical element includes a grounded transmission line.