Dc signal translator with a variable amplitude oscillator

Claim 2

An oscillator-isolator circuit for obtaining a DC output signal from and corresponding to a DC input signal where DC isolation is maintained between the input and the output of said circuit comprising: oscillator means including a transistor for generating an oscillating signal having an amplitude varying with a DC supply voltage for said oscillator means; transformer means associated with said oscillator means, said transformer means including an input winding DC coupled to said transistor and an output winding DC isolated from said transistor; feedback means coupled to said input winding; feedback rectifying means DC coupled to said feedback means for deriving a DC feedback signal from said oscillating signal; amplifier means having an input and an output, said DC feedback signal and said DC input signal being applied to the input of said amplifier means to produce a DC supply signal at the output of said amplifier means related to the difference between said DC feedback signal and said DC input signal, said DC feedback signal controlling said DC supply voltage for said oscillator means; and an output rectifying means DC coupled to said output winding for producing said isolated DC output signal.

Claim 3

The circuit of claim 1 wherein said feedback means comprises a feedback winding AC coupled to and DC isolated from said input winding and said output winding.

Claim 4

The circuit of claim 2 wherein said feedback winding is matched with said output winding.

Claim 5

The circuit of claim 3 wherein feedback rectifying means is matched with said output rectifying means so as to apply a DC feedback signal to said amplifier means which is substantially identical to said DC output signal.

Claim 6

The circuit of claim 4 wherein said oscillator means comprises a tank circuit including said input winding and said output winding, a first capacitance connected in parallel with a portion of said input winding and a second capacitance connected in parallel with said output winding.

Claim 7

The circuit of claim 5 wherein said input winding and said first capacitance are matched with said output winding and said second capacitance.

Claim 8

The circuit of claim 6 wherein said feedback rectifying means and said output rectifying means are matched so as to apply a DC feedback signal to said amplifier means which is substantially identical to said DC output signal.

Claim 9

The circuit of claim 1 further comprising: output amplifier means connected to the output of said output rectifying means, said output amplifier means having first and second output terminals; DC power supply means; load means; and power supply isolator means connected in series relationship with said DC power supply means and said load means between said first output terminal and second output terminal of said output amplifier means.

Claim 10

The circuit of claim 8 wherein said output amplifier means comprises: operational amplifier means having a pair of input terminals, an output terminal and at least one power supply terminal; operational amplifier input means for applying one portion of the output signal from said output rectifying means to one of said operational amplifier input terminals and applying another portion of the output signal from said output rectifying means to said at least one operational amplifier power supply terminal; an operational amplifier output stage for coupling said operational amplifier output terminal to said load means; and amplifier feedback means for coupling said load means to the other one of said input terminals.

Claim 11

The circuit of claim 9 wherein said operational amplifier input means comprises a voltage divider connected across said output rectifying means.

Claim 12

The circuit of claim 9 wherein said operational amplifier output stage comprises a transistor having a base terminal connected to said operational amplifier output terminal.

Claim 13

The circuit of claim 8 further comprising: a two-wire transmission means including a first wire connecting said series connected load means and power supply means with said power supply isolator means and a second wire connecting said series connected load means and power supply means with one of said output terminals of said output amplifier.

Claim 14

The circuit of claim 8 further comprising: shunt means connected between said first output terminal and said second output terminal of said output amplifier means for establishing an initial current through said power supply isolator means.

Claim 15

The circuit of claim 1 further comprising: output amplifier means connected to the output of said output rectifying means, said output amplifier means having first and second output terminals; DC power supply means connected to said first output terminal; and load means connected to said second output terminal and in series with said DC power supply means; said output amplifier means comprising: operational amplifier means having a pair of input terminals, an output terminal and at least one power supply terminal; operational amplifier input means for applying one portion of the output signal from said output rectifying means to one of said operational amplifier input terminals and applying another portion of the output signal from said output rectifying means to said at least one operational amplifier power supply terminal; an operational amplifier output stage for coupling said operational amplifier output terminal to said load means; and amplifier feedback means for coupling said load means to the other one of said input terminals.

Claim 16

A DC signal translator having a DC isolated input and output comprising: DC signal comparison means having a DC signal input, a feedback input and an output, said signal comparison means generating a DC output signal at said output related to the difference between the signal applied to said DC signal input and said feedback input; variable amplitude oscillator means having a control input, said output of said comparison means being coupled to said control input of said oscillator means so as to vary the amplitude of the oscillations in response to said DC output signal; isolating transformer means including an input winding and an output winding associated with said oscillator means, said oscillator means producing DC isolated oscillating signals at said input winding and said output winding; feedback rectifying means coupled between said transformer means and said feedback input of said signal comparison means so as to obtain a DC feedback signal related to the amplitude of said oscillating signals and apply said DC feedbacK signal to said feedback input of said signal comparison means; and output rectifying means coupled to said output winding so as to obtain a DC output signal corresponding to said DC input signal.

Claim 17

A DC signal translator having a DC isolated input and output comprising: DC signal comparison means having a DC signal input, a feedback input and an output, said signal comparison means generating a DC output signal at said output related to the difference between the signal applied to said DC signal input and said feedback input; variable amplitude oscillator means having a control input, said output of said comparison means being coupled to said control input of said oscillator means so as to vary the amplitude of the oscillations in response to said DC output signal; isolating transformer means including an input winding and an output winding associated with said oscillator means, said oscillator means producing DC isolated oscillating signals at said input winding and said output winding; feedback rectifying means coupled between said transformer means and said feedback input of said signal comparison means so as to obtain a DC feedback signal related to the amplitude of said oscillating signals and apply said DC feedbacK signal to said feedback input of said signal comparison means; and output rectifying means coupled to said output winding so as to obtain a DC output signal corresponding to said DC input signal.

Claim 18

The DC signal translator of claim 15 including output amplifier means coupled to and supplied by said output rectifying means.

Claim 19

The DC signal translator of claim 16 wherein said output amplifier means comprises: operational amplifier means having a pair of input terminals, an output terminal and at least one power supply terminal; amplifier input means for applying one portion of said DC output signal to one of said operational amplifier input terminals and another portion of the DC output signal to said at least one power terminal; amplifier output means for coupling said output terminal to a load means; and amplifier feedback means for coupling said load means to the other of said operational amplifier input terminals.