Magnetic sensor and an integrated circuit

Patent metadata

Field	Value
Publication number	US-10469005-B2
Application number	US-201715625622-A
Country	US
Kind code	B2
Filing date	Jun 16, 2017
Priority date	Aug 8, 2014
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

The present teaching relates to a magnetic sensor comprising an input port to be connected to an external power supply, a magnetic field detecting circuit configured to generate a magnet detection signal, an output control circuit configured to control operation of the magnetic sensor in response to the magnet detection signal, and an output port. The magnetic field detecting circuit includes a magnetic sensing element configured to detect an external magnetic field and output a detection signal, a signal processing element configured to amplify the detection signal and removing interference from the detection signal to generate processed detection signal, and an analog-digital conversion element configured to convert the processed detection signal into a magnet detection signal, and the output control circuit is configured to control the magnetic sensor to operate in at least one of a first state and a second state responsive to at least the magnet detection signal.

First claim

We claim:

1. A magnetic sensor, comprising:
an input port to be connected to an external power supply;
a magnetic field detecting circuit configured to generate a magnet detection signal;
an output control circuit configured to control operation of the magnetic sensor in response to the magnet detection signal; and
an output port,
wherein the magnetic field detecting circuit includes:
a magnetic sensing element configured to detect an external magnetic field and output a detection signal,
a signal processing element configured to amplify the detection signal and removing interference from the detection signal to generate a processed detection signal, and
a conversion element configured to convert the processed detection signal into the magnet detection signal, which is used to control the magnetic sensor to operate in at least one of a first state and a second state responsive to at least the magnet detection signal, wherein:
in the first state, a load current flows in a first direction from the output port to outside of the magnetic sensor, and
in the second state, a load current flows in a second direction opposite that of the first direction from the outside of the magnetic sensor into the output port of the magnetic sensor; and

wherein the detection signal includes a magnetic field signal and a deviation signal, the signal processing element comprises:
a first chopper switch configured to separate the detection signal into the deviation signal and the magnetic field signal corresponding to a chopper frequency and a baseband frequency, respectively;
a chopper amplifier configured to amplify the deviation signal and the magnetic field signal and to switch the amplified deviation signal and the amplified magnetic field signal onto the chopper frequency and the baseband frequency, respectively;
a filter circuit configured to filter out the deviation signal at the chopper frequency; and
a sample-and-hold circuit coupled between the chopper amplifier and the filter circuit,

wherein the sample-and-hold circuit is configured to sample a first pair of differential signals during a first half and a second half of a clock cycle, respectively, and output two pairs of sampled differential signals during the clock cycle.

2. The magnetic sensor of claim 1 , wherein the chopper amplifier comprises:
a first amplifier; and
a second chopper switch, wherein
the first amplifier is configured to perform first-stage amplification on the deviation signal and the magnetic field signal from the first chopper switch to generate the amplified deviation signal and the amplified magnetic field signal, respectively, and
the second chopper switch is configured to switch the amplified deviation signal and the amplified magnetic field signal onto the chopper frequency and the baseband frequency, respectively.

3. The magnetic sensor of claim 2 , wherein the first amplifier includes a folded cascode amplifier.

4. The magnetic sensor of claim 2 , wherein the chopper amplifier further comprises a second amplifier connected in series to the second chopper switch,
wherein the second amplifier is configured to perform second-stage amplification on the amplified deviation signal switched onto the chopper frequency and the amplified magnetic field signal switched onto the baseband frequency.

5. The magnetic sensor of claim 1 , wherein the filter circuit further comprises a first filter configured to compute a second pair of differential signals based on the two pairs of sampled differential signals.

6. The magnetic sensor of claim 5 , wherein the filter circuit further comprises a second filter configured to further amplify the second pair of differential signals, remove the deviation signal, and generate a third pair of differential signals.

7. The magnetic sensor of claim 6 , wherein the conversion element comprises:
a first comparator configured to compare an output voltage determined based on the third pair of differential signals with a high-voltage threshold;
a second comparator configured to compare the output voltage with a low-voltage threshold; and
a latch logic circuit configured to output a first voltage if the output voltage is greater than the high-voltage threshold or a second voltage if the output voltage is less than the low-voltage threshold, or to maintain the output of the conversion element if the output voltage is between the low-voltage threshold and the high-voltage threshold, wherein the high-voltage threshold and the low-voltage threshold are determined based on a pair of differential voltage references, wherein
the first comparator and the second comparator takes the third pair of differential signals from the filter circuit and the pair of differential voltage references as inputs.

8. The magnetic sensor of claim 7 , wherein the latch logic circuit is configured to:
output a first voltage if a magnetic field intensity reaches a pre-set working point,
output a second voltage if the magnetic field intensity does not reach a pre-set releasing point, or
maintain the output of the conversion element if the magnetic field intensity is between the pre-set releasing point and the pre-set working point.

9. The magnetic sensor of claim 1 , further comprising:
a rectifying circuit coupled with the input port and configured to provide a voltage supply to the magnetic field detection circuit, and
an output control circuit configured to control the magnetic sensor to operate in at least one of the first state and the second state based on the magnet detection signal,
wherein the output control circuit comprises:
a first switch coupled with the output port to form a first current path allowing the load current to flow from the output port of the magnetic sensor to outside of the magnetic sensor in the first state; and
a second switch coupled with the output port to form a second current path allowing the load current to flow from outside of the magnetic sensor to the output port of the magnetic sensor in the second state, wherein
the first switch is a diode,
the second switch is a diode or a transistor, and
the first switch and the second switch operate based on the magnet detection signal to selectively turn on the first current path and the second current path.

10. An integrated circuit comprising:
a magnetic sensor, wherein the magnetic sensor comprises:
an input port to be connected to an external power supply;
a magnetic field detecting circuit configured to generate a magnet detection signal;
an output control circuit configured to control operation of the magnetic sensor in response to the magnet detection signal; and
an output port, wherein the magnetic field detecting circuit includes:
a magnetic sensing element configured to detect an external magnetic field and output a detection signal,
a signal processing element configured to amplify the detection signal and removing interference from the detection signal to generate a processed detection signal, and
a conversion element configured to convert the processed detection signal into the magnet detection signal, which is used to control the magnetic sensor to operate in at least one of a first state and a second state responsive to at least the magnet detection signal, wherein:
in the first state, a load current flows in a first direction from the output port to outside of the magnetic sensor, and
in the second state, a load current flows in a second direction opposite that of the first direction from the outside of the magnetic sensor into the output port of the magnetic sensor; and

wherein the detection signal includes a magnetic field signal and a deviation signal, the signal processing element comprises:
a

Assignees

• Johnson Electric Sa
• Johnson Electric Int Ag

Inventors

• Guo Hui Min
• Lou Shu Zuo
• Chen Xiao Ming
• Cai Guang Jie
• Wong Chun Fai
• Li Yue
• Sun Chi Ping
• Liu Bao Ting
• Wang En Hui
• Xin Fei
• Yeung Shing Hin
• Yang Xiu Wen
• Liu li sheng
• Cui yan yun
• Huang Shu Juan

Classifications

• H02P6/30

  Arrangements for controlling the direction of rotation (H02P6/22 takes precedence) · CPC title

• H02K11/215

  Magnetic effect devices, e.g. Hall-effect or magneto-resistive elements · CPC title

• H02P7/05

  by means of electronic switching · CPC title

• H02P2207/05

  Synchronous machines, e.g. with permanent magnets or DC excitation · CPC title

• H02P7/295

  of the kind having one thyristor or the like in series with the power supply and the motor · CPC title