Variable attenuator

Claim 2

A digitally controlled attenuator having an input terminal and a common terminal adapted for connection across an analog signal source, and an output terminal, a plurality of series connected resistors with one end connected to the input terminal and the other end connected to the output terminal, a plurality of pairs of shunt circuit paths with one end of the paths of each pair connected to opposite ends of a series resistor and the opposite ends of the paths connected to said common terminal, each shunt circuit path comprising a series connected resistor and switch, means operating said switches in response to digital signals to control the attenuation of an analog input signal from said analog signal source connected between the input and common terminals, the input resistance of said attenuator being substantially constant in all switch conditions.

Claim 3

The attenuator as defined in claim 1 wherein the means operating said switches are arranged to operate the switches in one pair of paths in a complimentary manner.

Claim 4

The attenuator as defined in claim 1 including at least two pairs of said shunt circuit paths connected to one series resistor, the switches in each pair of paths being simultaneously opened and closed, with the switches in only one pair of shunt circuit paths for said one series resistor being closed at any one time.

Claim 5

A variable attenuator having a plurality of attenuator sections, an input terminal, an output terminal, and a common terminal, said input and common terminals being adapted for connection across an analog signal sourCe, each attenuator section comprising a series resistance path and at least one pair of shunt circuit paths, the series resistance paths being connected together in series between said input and output terminals, and the pair of shunt circuit paths being connected between said series resistance paths and said common terminal with the paths of each pair of shunt circuit paths connected to opposite ends of the series resistance paths, each shunt circuit path including a series connected resistor and switch, and means operating said switches in response to digital signals to control the attenuation of an analog input signal applied between the input and common terminals, the input resistance of each attenuator section being substantially constant for all switch conditions.

Claim 6

A variable attenuator having a plurality of attenuator sections, an input terminal, an output terminal, and a common terminal, said input and common terminals being adapted for connection across an analog signal sourCe, each attenuator section comprising a series resistance path and at least one pair of shunt circuit paths, the series resistance paths being connected together in series between said input and output terminals, and the pair of shunt circuit paths being connected between said series resistance paths and said common terminal with the paths of each pair of shunt circuit paths connected to opposite ends of the series resistance paths, each shunt circuit path including a series connected resistor and switch, and means operating said switches in response to digital signals to control the attenuation of an analog input signal applied between the input and common terminals, the input resistance of each attenuator section being substantially constant for all switch conditions.

Claim 7

The attenuator as defined in claim 4 which includes at least first, second, and third series connected attenuator sections, the second section having an input resistance substantially equal to the design load resistance of the first section, and the third section having an input resistance substantially equal to the design load resistance of the second section, the input resistance of the second and third sections being unequal.

Claim 8

The attenuator as defined in claim 4 which includes at least first, second, and third series connected attenuator sections, the second section having an input resistance substantially equal to the design load resistance of the first section, and the third section having an input resistance substantially equal to the design load resistance of the second section, and input resistance of the second and third sections being equal.

Claim 9

The attenuator as defined in claim 4 wherein the input resistance of at least two attenuator sections is substantially equal.

Claim 10

The attenuator as defined in claim 4 wherein the input resistance of at least two adjacent attenuator sections are unequal to minimize the insertion loss of the attenuator.

Claim 11

A variable attenuator comprising, a plurality of pilike networks connected in series with means for connecting an analog signal source to one end and a load to the other end thereof, each network comprising a series branch and a pair of shunt branches, and means for switching the shunt branches into and out of operation in the network to change the attenuation of the analog signal without substantially changing the input resistance of the network.

Claim 12

A variable attenuator comprising, a plurality of pilike networks connected in series with means for connecting an analog signal source to one end and a load to the other end thereof, each network comprising a series branch and a pair of shunt branches, and means for switching the shunt branches into and out of operation in the network to change the attenuation of the analog signal without substantially changing the input resistance of the network.

Claim 13

The attenuator as defined in claim 9 wherein said switching means for each pair of shunt branches comprises a pair of switches in the shunt branches operated in a complementary manner.

Claim 14

The attenuator as defined in claim 9 wherein at least one of said networks comprises a plurality of pairs of shunt branches, and said switching means for said one network includes means for selectively switching only one pair of shunt branches into operation and the remaining pairs out of operation.

Claim 15

The attenuator as defined in claim 11 including a quinary counter having a plurality of output signals for control of the switching means.

Claim 16

The attenuator as defined in claim 11 wherein said one network attenuates the analog signal from the signal source a first amount with one pair of shunt branches switched into the network and attenuates the analog signal a different amount with another pair of shunt branches switched into the network.

Claim 17

An attenuator comprising a binary operated pilike network and a quinary operated pilike network, means directly connecting the networks together in series circuit, means for connecting one end of the series connected networks to an analog signal source and the other end to a load, said binary operated network comprising a first series resistance branch and a first pair of shunt circuit branches, said quinary operated network comprising a second series resistance branch and a plurality of pairs of shunt circuit branches, each of said shunt circuit branches comprising a series connected resisTor and switch, and quinary-binary operated switching means for actuating said switches to change the attenuation of the signal from the analog input signal source without changing the input resistance of the networks.

Claim 18

An attenuator comprising a binary operated pilike network and a quinary operated pilike network, means directly connecting the networks together in series circuit, means for connecting one end of the series connected networks to an analog signal source and the other end to a load, said binary operated network comprising a first series resistance branch and a first pair of shunt circuit branches, said quinary operated network comprising a second series resistance branch and a plurality of pairs of shunt circuit branches, each of said shunt circuit branches comprising a series connected resisTor and switch, and quinary-binary operated switching means for actuating said switches to change the attenuation of the signal from the analog input signal source without changing the input resistance of the networks.