Integrated and combined phase shifter and isolation switch

Abstract

A phase shifter unit cell or a connected set of such cells that can be well isolated from external circuitry and which do not introduce insertion loss into an RF signal path, exhibit good return loss, and further provides additional advantages when combined with bracketing attenuator circuits. More particularly, embodiments integrate a high-isolation function within a phase shifter circuit by breaking the complimentary nature of the control signals to a phase shifter cell to provide greater control of switch states internal to the phase shifter cell and thus enable a distinct high-isolation state, and by including a switchable shunt termination resistor for use in the high-isolation state. Some embodiments are serially coupled to attenuator circuits to enable synergistic interaction that reduces overall die size and/or increases isolation. One such embodiment positions a high-isolation phase shifter cell in accordance with the present invention between bracketing programmable attenuators.