Fully differential current sensing

Patent metadata

Field	Value
Publication number	US-10345353-B2
Application number	US-201715810245-A
Country	US
Kind code	B2
Filing date	Nov 13, 2017
Priority date	Nov 13, 2017
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

A current detection system includes an inductor and a detection circuit coupled across the inductor. The inductor is configured to receive an input signal that includes an input current and generate a voltage across the inductor. The current detection circuit includes a sensing network and a transconductance amplifier. The sensing network includes a capacitor and is configured to monitor a voltage across the inductor. The transconductance amplifier is configured to receive a differential voltage indicative of a voltage drop across the capacitor and output a differential output current proportional to the differential voltage.

First claim

What is claimed is:

1. A current detection system, comprising:
an inductor configured to receive an input signal that includes an input current and generate a voltage across the inductor; and
a current detection circuit coupled across the inductor, the current detection circuit including:
a sensing network configured to monitor the voltage across the inductor, the sensing network including a capacitor; and
a transconductance amplifier configured to receive a differential voltage indicative of a voltage drop across the capacitor and output a differential output current proportional to the differential voltage,

wherein:
the differential output current includes a first output current and a second output current; and
the transconductance amplifier is configured to increase the first output current and decrease the second output current as the differential voltage increases.

2. The current detection system of claim 1 , wherein the capacitor is in parallel with the inductor and a first terminal of the capacitor is connected to a negative input of the transconductance amplifier and a second terminal of the capacitor connected to a positive input of the transconductance amplifier.

3. The current detection system of claim 2 , wherein the transconductance amplifier includes a transconductance loop circuit.

4. The current detection system of claim 3 , wherein the transconductance amplifier includes a cascoded stage to increase gain of the differential voltage.

5. The current detection system of claim 1 , wherein the current detection circuit further includes a low side circuit configured to receive the differential output current and, in response to the input current being greater than a threshold value, generate an alert signal.

6. The current detection system of claim 5 , wherein the low side circuit includes:
an operational amplifier configured to receive the differential output current and generate a single-ended amplified voltage from the differential output current; and
a comparator configured to receive the single-ended amplified voltage, compare the single-ended amplified voltage to a reference voltage, and generate the alert signal in response to the single-ended amplified voltage being greater than the reference voltage,
wherein the reference voltage corresponds with the threshold value.

7. The current detection circuit of claim 6 , wherein the comparator is configured to receive the single-ended amplified voltage directly from the operational amplifier without the single-ended amplified voltage being filtered.

8. The current detection circuit system of claim 1 , wherein the current detection circuit further includes a low side circuit configured to receive the differential output current and generate a signal indicative of the input current based on the differential output current, the low side circuit including:
an operational amplifier configured to receive the differential output current and generate a single-ended amplified voltage from the differential output current; and
an analog-to-digital converter (ADC) configured to receive the single-ended amplified voltage and generate a digital output signal proportional to the input current.

9. A current detection circuit, comprising
a high side circuit coupled across an inductor, the high side circuit including:
a transconductance amplifier configured to receive a differential voltage indicative of a voltage drop across the inductor and output a differential output current proportional to the differential voltage, the differential voltage including a first voltage and a second voltage and the differential output current including a first output current and a second output current; and

a low side circuit configured to receive the differential output current and generate a signal indicative of an input current into the filter based on the differential output current.

10. The current detection circuit of claim 9 , wherein the transconductance amplifier includes a transconductance loop circuit.

11. The current detection circuit of claim 10 , wherein the transconductance loop circuit includes a cascoded input stage.

12. The current detection circuit of claim 9 , wherein the transconductance amplifier includes:
a first transistor comprising a first drain, a first gate, and a first source, the first gate configured to receive the first voltage;
a second transistor comprising a second drain, a second gate, and a second source, the second gate configured to receive the second voltage;
a third transistor comprising a third drain, a third gate, and a third source, the third drain connected to the first source and the third source generating the first output current; and
a fourth transistor comprising a fourth drain, a fourth gate, and a fourth source, the fourth drain connected to the second source and the fourth source generating the second output current.

13. The current detection circuit of claim 12 , wherein the transconductance amplifier further includes a sense resistor connected to the first source, the second source, the third drain, and the fourth drain.

14. The current detection circuit of claim 9 , wherein the low side circuit includes an operational amplifier configured to receive the first output current and the second output current and generate a single-ended amplified voltage.

15. The current detection circuit of claim 14 , wherein the low side circuit further includes a comparator configured to receive the single-ended amplified voltage, compare the single-ended amplified voltage to a reference voltage, and generate an alert signal that indicates that the input current is greater than a threshold value in response to the single-ended amplified voltage being greater than the reference voltage, the reference voltage corresponding with the threshold value.

16. The current detection circuit of claim 15 , wherein the comparator is configured to receive the single-ended amplified voltage directly from the operational amplifier without the single-ended amplified voltage being filtered.

17. A method of detecting an inductor current in a system input signal, comprising:
receiving, by an inductor, the input signal; and
receiving a differential voltage indicative of a voltage drop across the inductor;
outputting a differential output current proportional to the differential voltage; and
generating a signal indicative of the input current based on the differential output current,

wherein generating a signal indicative of the input current includes:
receiving the differential output current;
generating a single-ended amplified voltage corresponding to the output current;
comparing the single-ended amplified voltage to a reference voltage; and
in response to the single-ended amplified voltage being greater than the reference voltage, generating an alert signal that indicates that the input current is greater than a threshold value.

18. The method of claim 17 , wherein the single-ended amplified voltage is compared with the reference voltage without being filtered.

Assignees

• Texas Instruments Inc

Inventors

• Banerji Sudeep
• Suryanarayana Dattatreya Baragur
• Gakhar Vikram
• Tadeparthy Preetam
• Lakhanpal Vikas
• Venkateswaran Muthusubramanian
• J Vishnuvardhan Reddy

Classifications

• G01R31/013 Primary

  Testing passive components (testing relays G01R31/3278; testing electrical windings, e.g. inductors G01R31/72) · CPC title

• H02M3/156

  with automatic control of output voltage or current, e.g. switching regulators · CPC title

• G01R1/203

  Resistors used for electric measuring, e.g. decade resistors standards, resistors for comparators, series resistors, shunts (resistors in general H01C; microwave or radiowave terminations H01P1/26; coupling devices H01R) · CPC title

• H02M3/1584

  with a plurality of power processing stages connected in parallel · CPC title

• H02M2001/0009

  Electricity · mapped topic