Impedance line matching device using feedback

Claim 2

A two terminal impedance circuit which has two terminals at which an analogue voltage appears, comprising: analogue to digital converter means for converting an analogue voltage at the two terminals into digital signals; digital processing means, which receives as input the output digital signals from said analogue to digital converter means, for processing the digital signals using a first filtering transfer function to produce output signals; digital to analogue converter means for converting the output digital signals from said digital processing means into analogue signals, the output from said digital to analogue converter means being connected to said two terminals to form a first feedback loop; analogue processing means, which receives as input an analog voltage appearing at said two terminals, for processing the analog signals using a second filtering transfer function to produce output signals; and means for superposing the output from said analog processing means with the output from said digital to analogue converter means, such superposed outputs being coupled to said two terminals to form a second loop, so that a low frequency component of the signals appearing at said two terminals is coupled to said first feed back loop and a high frequency component thereof is coupled to said second feed back loop.

Claim 3

The two terminal impedance circuit as claimed in claim 1 wherein the first transfer function is set in a manner programmable and controllable from outside.

Claim 4

The two terminal impedance circuit as claimed in claim 1 wherein the second transfer function is set in a manner programmable and controllable from outside.

Claim 5

The two terminal impedance circuit as claimed in either one of the claims 1 wherein the analogue processing means is set to become equal to the real number component of the desired impedance appearing at said two terminals in an extremely high frequency band.

Claim 6

The two terminal impedance circuit as claimed in claim 1 wherein the digital processing means includes a digital processing circuit having two coefficients which are externally controllable.

Claim 7

The two terminal impedance circuit as claimed in claim 1 further comprising an adder amplifier, disposed at a coupling point of the first feed back loop and the second feed back loop, the adder amplifier having a gain which is externally controllable, and wherein the digital processing means includes a digital circuit of one coefficient which is externally controllable.

Claim 8

The two terminal impedance circuit as claimed in either one of the claims 4 wherein the analogue processing means includes externally controlled circuits.

Claim 9

The two terminal impedance circuit as claimed in claim 1 wherein at least the analogue to digital converter means, the digital processing means, the digital to analogue converter means and the analogue processing means are included in an integrated circuit.

Claim 10

The two terminal impedance circuit as claimed in either one of the claims 1 wherein the digital processing means is programmable and controllable micro processor.

Claim 11

The two terminal impedance circuit as claimed in either one of the claims 1 wherein the digital processing means is comprised of a combination of multipliers and adders.

Claim 12

A two-to-four wire converter of the type having two-wire terminals at which an analog voltage appears, and four wire input terminals and output terminals, said converter comprising: analog to digital converter means for converting analog voltage appearing at said two-wire terminals into digital signals; digital processing means, which receives as input the output digital signals from said analog to digital converter means, for processing the digital signals using a first transfer function; digital to analog converter means for converting the output digital signals from the digital processing means into analog signals and producing an output which is fed to said two-wire terminals to form a first feed-back loop; a digital filter, having an output which is connected with the input of said digital processing means and an input which is connected with the output of said digital processing means; the signals of said four-wire input terminal being connected to the input of said digital filter; the signals of said four-wire output terminal, being connected to the output of said digital filter; analog processing means, which receives as input an analog voltage appearing at said two-wire terminals for processing such analog signals using a second transfer function; and means for superposing the output from said analog processing means with the output of said digital to analog converter means, such superposed outputs being coupled to said two-wire terminals to form a second feed-back loop, so that a low frequency component of the signals at said two-wire terminals is coupled to said first feed-back loop and a high frequency component thereof is coupled to said second feed-back loop.

Claim 13

A two-to-four wire converter of the type having two-wire terminals at which an analog voltage appears, and four wire input terminals and output terminals, said converter comprising: analog to digital converter means for converting analog voltage appearing at said two-wire terminals into digital signals; digital processing means, which receives as input the output digital signals from said analog to digital converter means, for processing the digital signals using a first transfer function; digital to analog converter means for converting the output digital signals from the digital processing means into analog signals and producing an output which is fed to said two-wire terminals to form a first feed-back loop; a digital filter, having an output which is connected with the input of said digital processing means and an input which is connected with the output of said digital processing means; the signals of said four-wire input terminal being connected to the input of said digital filter; the signals of said four-wire output terminal, being connected to the output of said digital filter; analog processing means, which receives as input an analog voltage appearing at said two-wire terminals for processing such analog signals using a second transfer function; and means for superposing the output from said analog processing means with the output of said digital to analog converter means, such superposed outputs being coupled to said two-wire terminals to form a second feed-back loop, so that a low frequency component of the signals at said two-wire terminals is coupled to said first feed-back loop and a high frequency component thereof is coupled to said second feed-back loop.

Claim 14

A two-to-four wire converter as claimed in claim 11 further comprising a decimation filter and an interpolation filter, the output signals from the analog to digital converter means being coupled through the decimation filter and the input signals to the digital analog converter means being coupled through the interpolation filter.

Claim 15

A circuit as in claim 1 wherein said filtering transfer function are of a complex type, and are functions of frequency.

Claim 16

A circuit as in claim 11 wherein said filtering transfer function are of a complex type, and are functions of frequency.