Back to results
US 7,696,786 B2Granted
Precision differential level shifter
AssigneeON Semiconductor
InventorsFrancois Laulanet, Cedric Bonaldi
Life of this patent
Estimating the term…
Abstract
A differential level shifter employs a variable current mirror to maintain a reference voltage at one output while the other output follows a differential input. Resistor networks allow postproduction trimming of load resistors and the current mirror, resulting in a precise and accurate output of the differential signal. An active cascode circuit enhances current mirror balance and high frequency operation.
Claims25
A circuit for shifting the reference level of a differential signal while preserving its amplitude, the circuit comprising:
- a negative input terminal;
- a positive input terminal;
- a first load resistor having a first end and a second end, the first end connected to the negative input terminal;
- a second load resistor having a first end and a second end, the first end connected to the positive input terminal;
- a first pass transistor having a first node, a second node and a control node, the first node connected to the second end of the first load resistor to form a negative output terminal, the control node connected to a selected reference voltage signal;
- a current mirror having a first current node, a second current node and a current control node, the first current node connected to the second node of the first pass transistor, the second current node connected to the second end of the second load resistor to form a positive output terminal;
- and
- a first amplifier having a negative input, a positive input and an output, the positive input connected to the negative output terminal, the negative input connected to the selected reference voltage signal, the output connected to the current control node of the current mirror.
5 more elements
A circuit for shifting the reference level of a differential signal while preserving its amplitude, the circuit comprising:
- a negative input terminal;
- a positive input terminal;
- a first load resistor having a first end and a second end, the first end connected to the negative input terminal;
- a second load resistor having a first end and a second end, the first end connected to the positive input terminal,
- wherein at least one of the load resistors comprises a trimmable resistor;
- a trimmable current mirror having a first current node, a second current node and a current control node, the current mirror configured to mirror the current passing through the first current node and the first load resistor and the current passing through the second current node and the second resistor such that the current passing through the first and second current nodes are mirrored to each other, the first current node connected to the second end of the first load resistor to form a negative output terminal, the second current node connected to the second end of the second load resistor to form a positive output terminal,
- wherein the trimmable resistor comprises a series string of resistors, at least one of the resistors in the series string being connected in parallel with a switchable resistor network comprising a parallel connection of resistors, each connected in series with a switch, wherein the resistance values of the series string of resistors vary according to a geometric progression with a common ratio substantially equal to about ½.
4 more elements
A circuit for shifting the reference level of a differential signal while preserving its amplitude, the circuit comprising:
- a negative input terminal;
- a positive input terminal;
- a first load resistor having a first end and a second end, the first end connected to the negative input terminal;
- a second load resistor having a first end and a second end, the first end connected to the positive input terminal,
- wherein at least one of the load resistors comprises a trimmable resistor;
- a trimmable current mirror having a first current node, a second current node and a current control node, the trimmable current mirror configured to mirror the current passing through the first current node and the first load resistor and the current passing through the second current node and the second resistor such that the current passing through the first and second current nodes are mirrored to each other, the first current node connected to the second end of the first load resistor to form a negative output terminal, the second current node connected to the second end of the second load resistor to form a positive output terminal;
- and
- a first pass transistor having a first node, a second node and a control node, the first node and second node connected in series between the second end of the first load resistor and the first current node of the trimmable current mirror.
5 more elements
A circuit for shifting the reference level of a differential signal while preserving its amplitude, the circuit comprising:
- a negative input terminal;
- a positive input terminal;
- a first load resistor having a first end and a second end, the first end connected to the negative input terminal;
- a second load resistor having a first end and a second end, the first end connected to the positive input terminal,
- wherein at least one of the load resistors comprises a trimmable resistor;
- a trimmable current mirror having a first current node, a second current node and a current control node, the current mirror configured to mirror the current passing through the first current node and the first load resistor and the current passing through the second current node and the second resistor such that the current passing through the first and second current nodes are mirrored to each other, the first current node connected to the second end of the first load resistor to form a negative output terminal, the second current node connected to the second end of the second load resistor to form a positive output terminal;
- a pass transistor having a first node, a second node and a control node, the first node and second node connected in series between the second end of the second load resistor and the second current node of the trimmable current mirror;
- and
- an amplifier having a negative input, a positive input and an output, the positive input of the amplifier connected to the first current node of the trimmable current mirror, the negative input of the amplifier connected to the second current node of the trimmable current mirror, and output of the second amplifier connected to the control node of the pass transistor.
6 more elements
Dependencies are inferred from the claim text.