| 摘要 |
A network is provided which is selectively configurable as a high pass and low pass filter. A pair of sets of field effect transistors FETS is provided, each set comprising three FETS connected in a T-configuration. A pair of the FETS in each set have a drain electrode of one FET coupled to the source electrode of the other FET to provide a series element of the T-configured set. The third FET has drain and source electrodes coupled between the common connection of the pair of FETS and ground to form a shunt element of the T-configured set. The gate electrodes of the series elements of a first one of the sets of FETS and the shunt element of the other set of the FETS are each fed a common control voltage signal. A first one of the sets of FETS is capacitively coupled between the input and output terminals of the network, and the second one of the set of FETS is inductively coupled between the input and output terminals of the network. One of a pair of complementary control signals is fed to each one of the gate electrodes of the FETS, and in response to a first state of said pair of control signals, the network is configured to provide a low pass filter having a first predetermined phase shift characteristic as a function of frequency over a predetermined operating frequency range. In response to a second, different set of said control signals, the network is reconfigured to provide a high pass filter section having a second, different predetermined phase shift characteristic as a function of frequency range. The difference in phase characteristics of the network configured as a low pass filter and a high pass filter is provided to be substantially constant over the predetermined frequency range, thereby providing a single phase shift bit.
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