Eight bit digital phase shifter utilizing plurality of switchable low pass filters

Claim 2

A digital phase shifter comprising a plurality of phase shift networks connected in series so that the total phase shift is the sum of the phase shift provided by each network, said plurality of networks including at least a first phase shifter network in the form of a low pass pi filter having shunt capacitive reactance and series inductive reactance, and digital means for selectively switching the value of the series inductive reactance between two fixed values to digitally vary the phase shift provided by said low pass pi filter.

Claim 3

A digital phase shifter comprising a plurality of phase shift networks connected in series so that the total phase shift is the sum of the phase shift provided by each network, said plurality of networks including at least a first phase shifter network in a form of a low pass pi filter having shunt capacitive reactance and series inductive reactance, means for changing the value of the series inductive reactance to vary the phase shift provided by said low pass pi filter, at least a second phase shifter network in the form of a low pass tee filter having shunt capacitive reactance and series inductive reactance, and means for selectively causing a signal traveling through said digital phase including to bypass said low pass tee filter by selectively shorting said series inductive reactance.

Claim 4

A digital phase shifter comprising a plurality of phase shift networks connected in series so that the total phase shift is the sum of the phase shift provided by each network, said plurality of networks including at least a first phase shifter network in a form of a low pass pi filter having shunt capacitive reactance and series inductive reactance, means for changing the value of the series inductive reactance to vary the phase shift provided by said low pass pi filter, at least a second phase shifter network in the form of a low pass tee filter having shunt capacitive reactance and series inductive reactance, and means for selectively causing a signal traveling through said digital phase including to bypass said low pass tee filter by selectively shorting said series inductive reactance.

Claim 5

A digital phase shifter comprising a plurality of phase shift networks connected in series so that the total phase shift is the sum of the phase shift provided by each network, said plurality of networks inclduing at least a first phase shifter network in the form of a low pass pi filter having shunt capacitive reactance and series inductive reactance, means for changing the value of the series inductive reactance to vary the phase shift provided by said low pass pi filter, wherein said means for changing the value of the series inductive reactance of the low pass pi filter comprises a first inductive reactance, a series connected second inductive reactance and a diode, said diode being capable of being placed in either of two conductive states, and means for causing said diode to assume a first state to cause said first and second inductive reactances to be connected in parallel and for causing said diode to assume a second state to cause said second inductive reactance to be effectively removed from said low pass pi filter.

Claim 6

A digital phase shifter comprising a plurality of phase shift networks connected in series so that the total phase shift is the sum of the phase shift provided by each network, said plurality of networks inclduing at least a first phase shifter network in the form of a low pass pi filter having shunt capacitive reactance and series inductive reactance, means for changing the value of the series inductive reactance to vary the phase shift provided by said low pass pi filter, wherein said means for changing the value of the series inductive reactance of the low pass pi filter comprises a first inductive reactance, a series connected second inductive reactance and a diode, said diode being capable of being placed in either of two conductive states, and means for causing said diode to assume a first state to cause said first and second inductive reactances to be connected in parallel and for causing said diode to assume a second state to cause said second inductive reactance to be effectively removed from said low pass pi filter.

Claim 7

A digital phase shifter comprising a plurality of phase shift networks connected in series so that the total phase shift is the sum of the phase shift provided by each network, said plurality of networks including at least a first phase shifter network in the form of a low pass pi filter having shunt capacitive reactance and series inductive reactance, means for varying the series inductive reactance to vary the phase shift provided by said first network, and at least a second phase shifter network in the form of a low pass tee filter having shunt capacitive reactance and series inductive reactance and means for selectively shorting said series inductive reactance of said low pass tee filter, wherein said means for shorting said low pass tee filter series inductive reactance comprises first diode means in series with said tee filter series inductive reactance and second diode means shunting said tee filter series inductive reactance, said first and second diode means being capable of assuming first and secOnd conductive states whereby when said first diode means is in a first conductive state and said second diode means is in a second conductive state, said series inductive reactance is short circuited to effectively remove the low pass tee filter from the phase shifter.

Claim 8

A digital phase shifter comprising a plurality of phase shift networks connected in series so that the total phase shift is the sum of the phase shift provided by each network, said plurality of networks including at least a first phase shifter network in the form of a low pass pi filter having shunt capacitive reactance and series inductive reactance, means for varying the series inductive reactance to vary the phase shift provided by said first network, and at least a second phase shifter network in the form of a low pass tee filter having shunt capacitive reactance and series inductive reactance and means for selectively shorting said series inductive reactance of said low pass tee filter, wherein said means for shorting said low pass tee filter series inductive reactance comprises first diode means in series with said tee filter series inductive reactance and second diode means shunting said tee filter series inductive reactance, said first and second diode means being capable of assuming first and secOnd conductive states whereby when said first diode means is in a first conductive state and said second diode means is in a second conductive state, said series inductive reactance is short circuited to effectively remove the low pass tee filter from the phase shifter.

Claim 9

The digital phase shifter of claim 4 wherein said means for varying the series inductive reactance of each of the low pass pi filters comprises a first inductive reactance and a series connected second inductive reactance and a diode, said diode being capable of being placed in either of two conductive states whereby in a first state said first and second inductive reactances are in parallel while in the second conductive state said second inductive reactance is effectively removed from said low pass pi network.

Claim 10

The digital phase shift network of claim 5 wherein said diodes in said low pass pi filters and said first and second diode means in said low pass tee filters comprise PIN diodes, each of said low pass tee filters comprising first and second series connected inductive reactances, said shunt capacitive reactance being coupled between said tee filter first and second series connected inductive reactances to ground, said first diode means comprising first and second PIN diodes, said second diode means comprising a third PIN diode in parallel with the series circuit comprising the first and second tee filter inductive reactances and said first and second PIN diodes.

Claim 11

A digital phase shifter comprising a plurality of phase shift networks connected in series so that the total phase shift is the sum of the phase shift provided by each network, said plurality of networks including at least a first phase shifter network in the form of a low pass pi filter having shunt capacitive reactance and series inductive reactance, means for varying the series inductive reactance to vary the phase shift provided by said first network, and at least a second phase shifter network in the form of a low pass tee filter having shunt capacitive reactance and series inductive reactance and means for selectively shorting said series inductive reactance of said low pass tee filter, wherein said phase shifter is an eight bit phase shifter each of the three smallest phase shift bits being comprised of said low pass pi filters, each of the next two smallest bits being comprised of said low pass tee filters, the three largest bits being formed from hybrid networks.

Claim 12

A digital phase shifter comprising a plurality of phase shift networks connected in series so that the total phase shift is the sum of the phase shift provided by each network, said plurality of networks including at least a first phase shifter network in the form of a low pass pi filter having shunt capacitive reactance and series inductive reactance, means for varying the series inductive reactance to vary the phase shift provided by said first network, and at least a second phase shifter network in the form of a low pass tee filter having shunt capacitive reactance and series inductive reactance and means for selectively shorting said series inductive reactance of said low pass tee filter, wherein said phase shifter is an eight bit phase shifter each of the three smallest phase shift bits being comprised of said low pass pi filters, each of the next two smallest bits being comprised of said low pass tee filters, the three largest bits being formed from hybrid networks.

Claim 13

The digital phase shifter of claim 7 wherein said means for shorting each of said low pass tee filter series inductive reactance comprises, first diode means in series with the tee filter series inductive reactance and second diode means shunting the tee filter series inductive reactance, said first and second diode means being capable of assuming first and second conductive states whereby when said first diode means is in a first conductive state and said second diode means is in a second conductive state, said series inductive reactance is short circuited to effectively remove the low pass tee filter from the phase shifter.

Claim 14

The digital phase shifter network as claimed in claim 8 further including bias means coupled to each low pass filter, said bias means coupled to said low pass pi filters being adapted to selectively forward or reverse bias said low pass pi filter PIN diodes to thereby selectively vary their series inductive reactance, said bias means coupled to said low pass tee filters being adapted to selectively forward bias said third PIN diodes while back biasing said first and second PIN diodes to thereby effectively remove the low pass tee filters from the phase shifter.