US 12,422,871 B2Granted

Low-power floating-rail reference generator

AssigneeCypress Semiconductor Corporation

InventorAdrian Lin

Life of this patent

Estimating the term…

Loading patent…

Abstract

A floating-rail reference generator and method of operating the same are provided. Generally, the generator includes a tracking current source coupled in series with a current scaling resistor between an input voltage (VBAT) and ground. The tracking current source is operable to receive a reference voltage and couple a tracking current through the resistor to produce a floating-rail reference voltage (VSSHV_REF) at an output between the tracking current source and scaling resistor, wherein: VSSHV_REF=((VBAT−VGS)/k)·1/R·k·R, where VGS is a desired constant potential difference between VBAT and VSSHV_REF, k is a voltage scaling ratio, and R is a resistance of the current scaling resistor. In some embodiments, the tracking current source includes a transistor coupled between VBAT and the output, and controlled by a differential amplifier.

Claims18

Dependent claims

A floating-rail reference generator comprising a tracking current source coupled in series with a current scaling resistor between an input voltage (VBAT) and ground, the tracking current source operable to receive a reference voltage and generate a tracking current (Isource) through the current scaling resistor to produce a floating-rail reference voltage (VSSHV_REF) at an output between the tracking current source current and scaling resistor,

wherein:
V
SSHV
⁢
_
⁢
REF
=
(
V
BAT
k
-
V
GS
k
)
·
1
R
·
k
·
R
where VGS is a constant potential difference between VBAT and VSSHV_REF, k is a voltage scaling ratio, and R is a resistance of the current scaling resistor;
and
wherein the tracking current source comprises a pair of MOS transistors including a first transistor coupled between the input voltage (VBAT) and the output and a second transistor, and a differential amplifier having an output coupled to gates of the first and second transistors and operable to control the first and second transistors, the differential amplifier comprising:
an inverting input coupled to the input voltage (VBAT) through a first resistor (R1) of a voltage divider and to ground through a second resistor (R2) of the voltage divider;
and
a non-inverting input coupled to a drain of the second transistor and to ground through a third resistor (R3).

27 more elements

A method of generating a floating-rail reference voltage comprising:

generating a reference voltage;
generating a tracking current (Isource) from the reference voltage;
and
coupling the tracking current (Isource) into a current scaling resistor having a resistance (R), to generate a floating-rail reference voltage (VSSHV_REF) equal to Isource·R at an output,
wherein generating the tracking current comprises controlling a pair of MOS transistors including a first transistor coupled between an input voltage (VBAT) and the output, and a second transistor, using a differential amplifier having an output coupled to gates of the first and second transistors, and wherein the differential amplifier comprises an inverting input coupled to the input voltage (VBAT) through a first resistor (R1) of a voltage divider and to ground through a second resistor (R2) of the voltage divider, and a non-inverting input coupled to the reference voltage.

2 more elements

A floating-rail reference generator comprising:

a current scaling resistor coupled between an output and ground, wherein a floating-rail reference voltage (VSSHV_REF) at the output:
V
SSHV
⁢
_
⁢
REF
=
(
V
BAT
k
-
V
GS
k
)
·
1
R
·
k
·
R
where VGS is a preselected maximum gate-source voltage for a fabrication process, R is a resistance of the current scaling resistor, and k is a voltage scaling ratio equal to a resistance of the second resistor (R2) divided by a sum of resistances of the first resistor (R1) and second resistor (R2);
a pair of MOS transistors including a first transistor having a source coupled to an input voltage (VBAT) and a drain coupled to the output, and a second transistor having a source coupled to the input voltage (VBAT);
a differential amplifier having an output coupled to gates of the first and second transistors and operable to control the first and second transistors, the differential amplifier comprising:
an inverting input coupled to the input voltage (VBAT) through a first resistor (R1) of a voltage divider and to ground through a second resistor (R2) of the voltage divider;
and
a non-inverting input coupled to a drain of the second transistor and to ground through a third resistor (R3).

27 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/307,328Filed 26 Apr 2023
Published: US 2024/0361790 A131 Oct 2024
Granted: 23 Sep 2025
Term ends: Not estimatedThe source records don’t support an estimate.

Classification3 codes

G05F 1/562
Using semiconductor devices in series with the load as final control devices: with a threshold detection shunting the control path of the final…
G05F 1/465
As a function of the requirements of the load, e.g. delay, temperature, specific voltage/current characteristic: internal voltage generators for…
G05F
Systems for regulating electric or magnetic variables