US-12627259-B2 - Isolated power supply chip based on symmetrical class-D oscillator with dead zone control

US12627259B2US 12627259 B2US12627259 B2US 12627259B2US-12627259-B2

Abstract

An isolated power supply chip based on a symmetrical Class-D oscillator with dead zone control is provided, including: a transmitting stage oscillator circuit connected to a power supply and a ground, the oscillator circuit is configured to invert an input DC voltage into differential high-frequency oscillation power signals and input the signals to a primary coil of a transformer; a rectifier circuit connected to a secondary coil of the transformer and configured to rectify the signals to output a DC voltage signal; and a feedback control circuit configured to feed back the DC voltage signal to the oscillator circuit; the oscillator circuit comprises: a dead zone control module, and a NMOS transistor group and a PMOS transistor group connected to the dead zone control module that are symmetrically arranged, the dead zone control module is configured to control the transistor groups to eliminate a short circuit current.

Inventors

Lin Cheng
Dongfang Pan

Assignees

UNIVERSITY OF SCIENCE AND TECHNOLOGY OF CHINA

Dates

Publication Date: 20260512
Application Date: 20220216

Claims (8)

1 . An isolated power supply chip based on a symmetrical Class-D oscillator with dead zone control, with electromagnetic interference radiation caused by common-mode current suppressed, the isolated power supply chip comprising: a transmitting stage oscillator circuit connected to a power supply and a ground, wherein the transmitting stage oscillator circuit is configured to invert an input DC voltage into differential high-frequency oscillation power signals and input the differential high-frequency oscillation power signals to a primary coil of a subsequent transformer; a rectifier circuit connected to a secondary coil of the transformer and configured to rectify the differential high-frequency oscillation power signals to output a DC voltage signal; and a feedback control circuit connected to the rectifier circuit and configured to feed back the DC voltage signal to the transmitting stage oscillator circuit, so as to modulate and stabilize the DC voltage signal; wherein the transmitting stage oscillator circuit comprises: a dead zone control module, and a NMOS transistor group and a PMOS transistor group connected to the dead zone control module that are symmetrically arranged, the dead zone control module is configured to control a turn-on and a turn-off of the NMOS transistor group and the PMOS transistor group to eliminate a short circuit current between the power supply and the ground, wherein the NMOS transistor group comprises a first NMOS transistor and a second NMOS transistor, the PMOS transistor group comprises a first PMOS transistor and a second PMOS transistor, the dead zone control module comprises a first bias voltage, a second bias voltage, a first bias resistor, a second bias resistor, a third bias resistor, a fourth bias resistor, the first bias voltage is connected to a gate electrode of the first NMOS transistor through the first bias resistor, and is connected to a gate electrode of the second NMOS transistor through the second bias resistor; the second bias voltage is connected to a gate electrode of the first PMOS transistor through the third bias resistor, and is connected to a gate electrode of the second PMOS transistor through the fourth bias resistor, the first bias voltage and the second bias voltage satisfy: V BP −V BN >V DD −|V THP |−V THN wherein V BN represents the first bias voltage, V BP represents the second bias voltage, V DD represents a voltage of the power supply, V THN represents a threshold voltage of the NMOS transistor group, V THP represents a threshold voltage of the PMOS transistor group, wherein the drain electrode of the first NMOS transistor and the drain electrode of the first PMOS transistor are connected to a first end of the primary coil, and the drain electrode of the second NMOS transistor and the drain electrode of the second PMOS transistor are connected to a second end of the primary coil, so as to input the differential high-frequency oscillation power signals to the first end and the second end of the primary coil respectively.
2 . The isolated power supply chip according to claim 1 , wherein the dead zone control module is configured to control the turn-on and the turn-off of the NMOS transistor group and the PMOS transistor group by sampling the high-frequency oscillation power signals at the first end and the second end of the primary coil of the transformer, so as to achieve a dead zone control.
3 . The isolated power supply chip according to claim 2 , wherein the dead zone control module is configured to control a turn-on and a turn-off of each power transistor of the NMOS transistor group and the PMOS transistor group by outputting a control voltage signal according to the sampled high-frequency oscillation power signals at the first end and the second end of the primary coil of the transformer, so as to achieve the dead zone control.
4 . The isolated power supply chip according to claim 1 , further comprising: a switch, wherein one end of the switch is connected to the ground or the power supply, and another end of the switch is connected to the transmitting stage oscillator circuit, the switch is configured to control whether the transmitting stage oscillator circuit oscillates or not by switching on and switching off according to the DC voltage signal fed back by the feedback control circuit.
5 . The isolated power supply chip according to claim 1 , wherein the transmitting stage oscillator circuit comprises states of: state 1: the second NMOS transistor and the first PMOS transistor are turned on, and an inductor current I L is negative; state 2: the second NMOS transistor and the first PMOS transistor are turned on, and the inductor current I L is positive; state 3: the second NMOS transistor and the first PMOS transistor are turned off, and voltages V GN2 and V OPI output by the dead zone control module reach V THN and V DD −|V THP |, respectively, while a dead time is generated, all four power transistors are turned off, and the inductor current I L freewheels; state 4: the first NMOS transistor and the second PMOS transistor are turned on, and the inductor current I L is positive; state 5: the first NMOS transistor and the second PMOS transistor are turned on, and the inductor current I L is negative; and state 6: the first NMOS transistor and the second PMOS transistor are turned off, voltages V GN1 and V GP2 output by the dead zone control module reach V THN and V DD −|V THP |, respectively, while a dead time is generated, all four power transistors are turned off, and the inductor current I L freewheels; where a high-frequency oscillation power signal corresponding to the first end of the primary coil of the transformer is V PP , a high-frequency oscillation power signal corresponding to the second end of the primary coil of the transformer is V PN , the inductor current generated by the primary coil of the transformer is I L , V GN1 is a gate voltage of the first NMOS transistor output by the dead zone control module, V GN2 is a gate voltage of the second NMOS transistor output by the dead zone control module, V GP1 is a gate voltage of the first PMOS transistor output by the dead zone control module, and V GP2 is a gate voltage of the second PMOS transistor output by the dead zone control module.
6 . The isolated power supply chip according to claim 1 , wherein the dead zone control module further comprises a first coupling capacitor, a second coupling capacitor, a third coupling capacitor, and a fourth coupling capacitor.
7 . The isolated power supply chip according to claim 6 , wherein the gate electrode of the first NMOS transistor is connected to a drain electrode of the second NMOS transistor through the first coupling capacitor, the gate electrode of the second NMOS transistor is connected to a drain electrode of the first NMOS transistor through the second coupling capacitor, the gate electrode of the first PMOS transistor is connected to a drain electrode of the second PMOS transistor through the third coupling capacitor, and the gate electrode of the second PMOS transistor is connected to a drain electrode of the first PMOS transistor through the fourth coupling capacitor.
8 . The isolated power supply chip according to claim 1 , wherein the first bias voltage or the second bias voltage is used to adjust a common-mode voltage of the NMOS transistor group or the PMOS transistor group, so as to achieve the dead zone control.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S) This application is a Section 371 National Stage Application of International Application No. PCT/CN2022/076474, filed on Feb. 16, 2022, entitled “ISOLATED POWER CHIP BASED ON DEADBAND CONTROL SYMMETRICAL CLASS-D OSCILLATOR”, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD The present disclosure relates to a field of isolated power supply technology, and in particular, to an isolated power supply chip based on a symmetrical Class-D oscillator with dead zone control. BACKGROUND Isolated power supply chips are widely used in automotive electronics, biomedical, defense electronic systems, communication systems and other fields. Especially when noise-sensitive equipment operates under some extreme conditions, the isolated power supply chips play a vital role in ensuring the safety and reliability of the equipment. As a size of the isolated power supply becomes smaller and smaller, the frequency and power density of a power oscillation signal inside the chip are getting higher and higher. The isolated power supply chip often becomes a radiation source and interferes with other electronic equipment, that is, there may be a problem of electromagnetic interference (EMI). The radiation source includes unilateral radiation and dipole radiation. The unilateral radiation may generally be solved by bypass capacitors on two sides of the isolated power supply. The main problem of the isolated power supply chip is that the dipole radiation from input to output is difficult to eliminate, and EMI testing is an important certification project before electronic devices become products. However, the traditional methods of reducing EMI for isolated power supply chip are through the application level, that is, using at least four layers of staggered capacitors and ferrite bead devices on the PCB board, which greatly increases the design cost and may not fundamentally solve the EMI radiation problem. Furthermore, there are also technical problems such as low conversion efficiency. SUMMARY The present disclosure provides an isolated power supply chip based on a symmetrical Class-D oscillator with dead zone control, including: a transmitting stage oscillator circuit connected to a power supply and a ground, wherein the transmitting stage oscillator circuit is configured to invert an input DC voltage into differential high-frequency oscillation power signals and input the differential high-frequency oscillation power signals to a primary coil of a subsequent transformer; a rectifier circuit connected to a secondary coil of the transformer and configured to rectify the differential high-frequency oscillation power signals to output a DC voltage signal; and a feedback control circuit connected to the rectifier circuit and configured to feed back the DC voltage signal to the transmitting stage oscillator circuit, thereby modulating and stabilizing the DC voltage signal; wherein the transmitting stage oscillator circuit comprises: a dead zone control module, and a NMOS transistor group and a PMOS transistor group connected to the dead zone control module that are symmetrically arranged, the dead zone control module is configured to control a turn-on and a turn-off of the NMOS transistor group and the PMOS transistor group to eliminate a short circuit current between the power supply and the ground. Optionally, the dead zone control module is configured to control the turn-on and the turn-off of the NMOS transistor group and the PMOS transistor group by sampling the high-frequency oscillation power signals at two ends of the primary coil of the transformer, so as to achieve a dead zone control. Optionally, the dead zone control module is configured to control a turn-on and a turn-off of each power transistor of the NMOS transistor group and PMOS transistor group by outputting a control voltage signal according to the sampled high-frequency oscillation power signals at two ends of the primary coil of the transformer, so as to achieve the dead zone control. Optionally, the NMOS transistor group comprises a first NMOS transistor and a second NMOS transistor; the PMOS transistor group comprises a first PMOS transistor and a second PMOS transistor. Optionally, the isolated power supply chip further includes: a switch, wherein one end of the switch is connected to the ground or the power supply, and another end of the switch is connected to the transmitting stage oscillator circuit, the switch is configured to control whether the transmitting stage oscillator circuit oscillates or not by switching on and switching off according to the DC voltage signal fed back by the feedback control circuit. Optionally, the transmitting stage oscillator circuit includes states of: state 1: a second NMOS transistor and a first PMOS transistor are turned on, and an inductor current IL is negative;state 2: the second NMOS transistor and the first PMOS transistor are turned on, an