US 12,422,871 B2
Low-power floating-rail reference generator
Adrian Lin, Austin, TX (US)
Assigned to Cypress Semiconductor Corporation, San Jose, CA (US)
Filed by Cypress Semiconductor Corporation, San Jose, CA (US)
Filed on Apr. 26, 2023, as Appl. No. 18/307,328.
Prior Publication US 2024/0361790 A1, Oct. 31, 2024
Int. Cl. G05F 1/56 (2006.01); G05F 1/46 (2006.01)
CPC G05F 1/562 (2013.01) [G05F 1/465 (2013.01)] 18 Claims
OG exemplary drawing
 
1. 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:

OG Complex Work Unit Math
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).