Voltage level shifter circuit with current ratio control of transconductive impedance of semiconductor

Claim 2

A voltage level shifter comprising a controllable transconductive impedance having an impedance control electrode, said transconductive impedance coupling a first terminal and a second terminal of said shifter, a floating reference voltage source, and a feedback network to compare the reference voltage with the voltage at the second terminal, said feedback network including a pair of amplifier devices having amplifier control electrodes, said amplifier devices having main transmission paths coupled to interconnect a constant-current source and the impedance control terminal of said transconductive impedance, the amplifier control electrodes of said pair of amplifier devices being coupled respectively to the reference voltage and the voltage at the second terminal, a second constant-current source, said reference voltage source comprising a reference impedance interconnecting the first terminal of said shifter and the second constant-current source, the conductivity of the transmission paths of said pair of amplifier devices reflecting the relative magnitude of the reference voltage and the voltage at the second terminal and adjusting the impedance of said transconductive impedance to adjust the voltage at the second terminal to equal the reference voltage.

Claim 3

A voltage level shifter as defined in claim 1 further including means to limit the current flow in the transmission path of at least one of said paired amplifier devices to a fixed limit, said means to limit including a current path to transmit current exceeding the fixed limit to the second terminal of said shifter.

Claim 4

A voltage level shifter as defined in claim 1 further including a second transconductive impedance coupling a third terminal to a fourth terminal and a second floating reference voltage source, said second reference voltage sources including a second reference impedance, said first and second reference impedances coupled respectively through first and second controlled impedances to said second constant-current source, said first and second controlled impedances being independently controllable to independently control the voltage level shift across said First and second transconductive impedances, respectively.

Claim 5

A voltage level shifter as defined in claim 1 wherein said transconductive impedance comprises a regulator transistor whose collector-emitter path couples the said terminals of the shifter and said pair of amplifier devices comprises a pair of emitter-coupled transistors whose collector-emitter paths couple at least one electrode of said regulator transistor to said constant current source.

Claim 6

A level-shifting circuit as defined in claim 2 further including means to compensate for variations in the voltage level shift due to the capacitance of the amplifier control electrodes of said pair of amplifier devices, said means to compensate including means to generate a voltage in response to current drawn by the capacitance of at least one of said control electrodes.

Claim 7

A level-shifting circuit for introducing a fixed voltage shift between an input and an output terminal comprising a first transistor having its transconductive path interconnecting said input and output terminal, a first and a second constant-current source, a first impedance to establish the magnitude of said voltage shift and connected to said first constant-current source, a second transistor interconnecting said input terminal to said second constant-current source and conducting current in response to the voltage drop across said first impedance, and a third transistor interconnecting the control electrode of said first transistor to said second constant-current source and conducting current in response to the voltage at said output terminal whereby the ratio of the respective current flow in said second and third transistors adjusts the conductivity level of the transconductive path of said first transistor to maintain a fixed voltage shift between said input and output terminals.

Claim 8

A level-shifting circuit for introducing a fixed voltage shift between an input and an output terminal comprising a first transistor having its transconductive path interconnecting said input and output terminal, a first and a second constant-current source, a first impedance to establish the magnitude of said voltage shift and connected to said first constant-current source, a second transistor interconnecting said input terminal to said second constant-current source and conducting current in response to the voltage drop across said first impedance, and a third transistor interconnecting the control electrode of said first transistor to said second constant-current source and conducting current in response to the voltage at said output terminal whereby the ratio of the respective current flow in said second and third transistors adjusts the conductivity level of the transconductive path of said first transistor to maintain a fixed voltage shift between said input and output terminals.

Claim 9

A level-shifting circuit as defined in claim 6 further including a fourth transistor whose transconductive path couples the input terminal to the output terminal and whose control electrode is connected to the transconductive path of said second transistor and a shunt impedance coupling the input terminal to said second transistor and connected in parallel with a junction of said fourth transistor whereby said shunt impedance limits the magnitude of current transmitted from the input terminal to said second transistor.

Claim 10

A level-shifting circuit for introducing a fixed voltage shift between an input and an output terminal comprising a first transistor having its transconductive path interconnecting said input and output terminal, a first and a second constant current source, a first impedance to establish the magnitude of said voltage shift and interconnecting said input terminal to said first constant-current source, a second transistor whose transconductive path interconnects said input terminal to said second constant current source and having its transconductive impedance responsive to the voltage drop across said first impedance, a third transistor whose transconductive path interconnects the control electrode of said first transistor to said second constant-current source and having its transconductive impedance responsive to the voltage at said output terminal and a current path including a second impedance to supply current from said input terminal to the transconductive path of said third transistor whereby the ratio of the respective current flows in the transconductive paths of said second and third transistor adjusts the conductivity level of the transconductive path of said first transistor to maintain the fixed voltage shift between said input and output terminals.

Claim 11

A level-shifting circuit for introducing a fixed voltage shift between an input and an output terminal comprising a first transistor having its transconductive path interconnecting said input and output terminal, a first and a second constant current source, a first impedance to establish the magnitude of said voltage shift and interconnecting said input terminal to said first constant-current source, a second transistor whose transconductive path interconnects said input terminal to said second constant current source and having its transconductive impedance responsive to the voltage drop across said first impedance, a third transistor whose transconductive path interconnects the control electrode of said first transistor to said second constant-current source and having its transconductive impedance responsive to the voltage at said output terminal and a current path including a second impedance to supply current from said input terminal to the transconductive path of said third transistor whereby the ratio of the respective current flows in the transconductive paths of said second and third transistor adjusts the conductivity level of the transconductive path of said first transistor to maintain the fixed voltage shift between said input and output terminals.