Noise detecting circuit and associated system and method
View Patent ↗A noise detecting circuit including an amplifier circuit, a filtering circuit and a comparing circuit. The amplifier circuit is arranged to amplify an input signal and output an amplified signal, wherein the input signal is received from a circuit to be detected and indicates a noise level of the circuit to be detected. The filtering circuit is coupled to the amplifier circuit and arranged to filter the amplified signal and output a filtered signal. The comparing circuit is coupled to the filtering circuit and arranged to compare the filtered signal to a reference voltage and output an output signal indicating the noise level of the circuit to be detected.
1. A noise detecting circuit, comprising:
an amplifier circuit, arranged to amplify an input signal indicating a noise level of a circuit to be detected and output an amplified signal;
a filtering circuit, arranged to receive and filter the amplified signal and output a filtered signal; and
a comparing circuit, arranged to receive and compare the filtered signal to a reference voltage and output an output signal;
wherein the amplifier circuit comprises:
an output terminal;
an operational transconductance amplifier (OTA), connected to the output terminal;
a first resistor, coupled between the output terminal and an input terminal of the OTA; and
a second resistor, coupled to the input terminal of the OTA;
a capacitor, coupled between the second resistor and a reference voltage source.
2. The noise detecting circuit of claim 1 , wherein the filtering circuit comprises:
an output terminal; and
a first filter, selectively coupled to the output terminal, comprising:
a sub-output terminal;
a switch, arranged to selectively couple the sub-output terminal to the output terminal;
a resistor, wherein a terminal of the resistor is coupled to the amplifier circuit and another terminal of the resistor is coupled to the sub-output terminal; and
a capacitor, wherein a terminal of the capacitor is coupled to the sub-output terminal and another terminal of the capacitor is coupled to a reference voltage source.
3. The noise detecting circuit of claim 2 , wherein the filtering circuit further comprises:
a second filter, selectively coupled to the output terminal, wherein a corner frequency of the first filter and a corner frequency of the second filter are different.
4. The noise detecting circuit of claim 2 , further comprising:
a switching circuit, arranged to selectively couple the output terminal to the comparator.
5. The noise detecting circuit of claim 4 , further comprising:
a buffer, wherein the switching circuit is further arranged to selectively coupled the output terminal to the buffer.
6. The noise detecting circuit of claim 1 , wherein the comparing circuit comprises:
a comparator, arranged to compare the filtered signal to the reference voltage to output the output signal.
7. The noise detecting circuit of claim 6 , wherein the comparing circuit comprises:
a voltage-to-current converter, coupled to the comparator and arranged to convert the output signal from a voltage form into a current form.
8. A noise detecting system, comprising:
an amplifier circuit, arranged to amplify an input signal indicating a noise level of a circuit to be detected and output an amplified signal;
a filtering circuit, arranged to receive and filter the amplified signal and output a filtered signal;
a comparing circuit, arranged to receive and compare the filtered signal to a reference voltage and output an output signal; and
an analyze device, coupled to the comparing circuit via a first output pad and arranged to generate a CDF in response to the output signal and the reference voltage;
a switching circuit, comprising a plurality of switches;
wherein the amplifier circuit comprises:
an output terminal;
an operational transconductance amplifier (OTA), connected to the output terminal;
a first resistor, coupled between the output terminal and an input terminal of the OTA; and
a second resistor, coupled to the input terminal of the OTA;
wherein each switch is coupled between the circuit to be detected and the second resistor.
9. The noise detecting system of claim 8 , wherein the filtering circuit comprises:
a plurality of filters, wherein each filter has different corner frequency and a corresponding switch for selectively coupling the filter to the comparing circuit.
10. The noise detecting system of claim 8 , wherein the comparing circuit comprises a comparator.
11. The noise detecting system of claim 8 , wherein the analyze device is further arranged to display a voltage level, which corresponds to the noise level, in response to the corner frequency based on the CDF.
12. The noise detecting system of claim 8 , further comprising:
a clock generator, coupled to the comparing circuit via a second output pad and arranged to provide a clock signal to the comparing circuit.
13. A noise detecting method, comprising:
receiving an input signal from a circuit to be detected;
outputting an amplified signal by amplifying the input signal;
outputting a filtered signal by filtering the amplified signal by a filter having a bandwidth; and
outputting an output signal indicating a noise level of the circuit to be detected by comparing the filtered signal to a reference voltage;
generating a CDF in response to the output signal and the reference voltage; and
deriving a voltage level, which corresponds to the noise level, in response to the bandwidth based on the CDF;
wherein outputting the amplified signal by amplifying the input signal comprises:
utilizing an amplifier to amplify the input signal, wherein the amplifier comprises:
an output terminal;
an operational transconductance amplifier (OTA), connected to the output terminal;
a first resistor, wherein a terminal of the first resistor is coupled to the output terminal, and another terminal of the first resistor is coupled to an input terminal of the OTA; and
a second resistor, wherein a terminal of the second resistor is coupled to the input terminal of the OTA.
14. The method of claim 13 , wherein the filter comprises:
an output terminal;
a first filter, selectively coupled to the output terminal, comprising:
a sub-output terminal;
a switch, arranged to selectively couple the sub-output terminal to the output terminal;
a resistor, wherein a terminal of the resistor is coupled to the amplifier circuit and another terminal of the resistor is coupled to the sub-output terminal; and
a capacitor, wherein a terminal of the capacitor is coupled to the sub-output terminal and another terminal of the capacitor is coupled to a reference voltage source.
15. The method of claim 14 , wherein outputting the output signal indicating the noise level of the circuit to be detected by comparing the filtered signal to the reference voltage comprises:
utilizing a comparing circuit to compare the filtered signal to the reference voltage,
wherein the comparing circuit comprises:
a comparator, arranged to compare the filtered signal to the reference voltage to output the output signal.
16. The noise detecting system of claim 8 , wherein the amplifier circuit further comprises:
a capacitor, coupled between the second resistor and a reference voltage source.
17. The noise detecting system of claim 8 , wherein the amplifier circuit further comprises:
a low dropout regulator (LDO), coupled between the second resistor and a reference voltage source.
18. The noise detecting system of claim 8 , wherein one terminal of the second resistor is coupled to the circuit to be detected.
19. The noise detecting circuit of claim 1 , wherein the input signal is received from the circuit to be detected.
20. The noise detecting circuit of claim 1 , wherein the filtering circuit is coupled to the amplifier circuit, and the comparing circuit is coupled to the filtering circuit.