Detection circuit and related electronic apparatus
Disclosed in the present application are a detection circuit and a related electronic apparatus. A detection circuit is used for determining the amplitude of a received signal that is generated by a receiver after same receives an input signal, and includes an operational amplifier; a capacitor unit, which is coupled between an output end and a negative end of the operational amplifier; a reset switch, which is arranged in parallel with the capacitor unit; a first switch, which is coupled between a reference voltage and an output end of the receiver; and a second switch, which is coupled between the output end of the receiver and the negative end of the operational amplifier, wherein in a general stage, the received signal includes a plurality of waves with a period T.
1 . A detection circuit, configured to determine an amplitude of a received signal generated by a receiver after the receiver receives an input signal, wherein the detection circuit comprises:
an operational amplifier, having a positive end, a negative end and an output end;
a capacitor unit, coupled between the output end and the negative end of the operational amplifier;
a reset switch, arranged in parallel with the capacitor unit;
a first switch, coupled between a reference voltage and an output end of the receiver; and
a second switch, coupled between the output end of the receiver and the negative end of the operational amplifier;
wherein:
in a reset stage, the reset switch is turned on and the second switch is turned off, the output end of the operational amplifier outputs the reference voltage; and
in a general stage, the reset switch is turned off, and the received signal comprises a plurality of waves with a period of T, and in a period T corresponding to a first specific wave of the plurality of waves, the detection circuit is set to a sampling mode for time period of T*R and set to a non-sampling mode for time period of T*(1−R), wherein R is greater than 0 and smaller than 1; and in a period T corresponding to a second specific wave of the plurality of waves, the detection circuit is set to the sampling mode for a time period of T*R and set to the non-sampling mode for a time period of T*(1−R), wherein:
in the sampling mode, the first switch is turned off and the second switch is turned on, so that the amplitude change of the received signal during the sampling mode is reflected in a specific proportion and is accumulated at the output end of the operational amplifier; and
in the non-sampling mode, the first switch is turned on and the second switch is turned off, so that the amplitude change of the received signal generated by the receiver in the non-sampling mode does not respond and does not accumulate at the output end of the operational amplifier, so that the voltage at the output end of the operational amplifier remains constant in the non-sampling mode.
2 . The detection circuit according to claim 1 , wherein the receiver equivalently includes:
a signal generator, configured to generate the received signal according to the input signal; and
a receiver capacitor, coupled to the signal generator and configured to receive the received signal, wherein the capacitance of the capacitor unit is CI, and the capacitance of the receiver capacitor is CS.
3 . The detection circuit according to claim 2 , wherein R is 1/2, and:
the detection circuit is set to the sampling mode during the time period of T/2 when the first specific wave drops from its peak to its trough;
the detection circuit is set to the non-sampling mode during the time period of T/2 when the first specific wave rises from its trough to its peak;
the detection circuit is set to the sampling mode during the time period of T/2 when the second specific wave drops from its peak to its trough; and
the detection circuit is set to the non-sampling mode during the time period of T/2 when the second specific wave rises from its trough to its peak.
4 . The detection circuit according to claim 3 , wherein the voltage difference between the peak and trough of the first specific wave is 2*VA, and the first specific wave drops from the peak to the trough, so that the voltage of the output end of the operational amplifier increases by 2*VA*CS/CI.
5 . The detection circuit according to claim 2 , wherein R is 1/2, and:
the detection circuit is set to the sampling mode during the time period of T/2 when the first specific wave rises from its trough to its peak;
the detection circuit is set to the non-sampling mode during the time period of T/2 when the first specific wave drops from its peak to its trough;
the detection circuit is set to the sampling mode during the time period of T/2 when the second specific wave rises from its trough to its peak; and
the detection circuit is set to the non-sampling mode during the time period of T/2 when the second specific wave drops from its peak to its trough.
6 . The detection circuit according to claim 5 , wherein voltage difference between the peak and trough of the first specific wave is 2*VA, and the first specific wave rises from the trough to that peak, so that the voltage of the output end of the operational amplifier decreases by 2*VA*CS/CI.
7 . The detection circuit according to claim 1 , wherein in the general stage, in a period T corresponding to a third specific wave of the plurality of waves, the detection circuit is set to the non-sampling mode for whole period T, wherein the third specific waves is between the first specific wave and the second specific wave.
8 . The detection circuit according to claim 1 , wherein the positive end of the operational amplifier is coupled to the reference voltage.
9 . The detection circuit according to claim 8 , wherein the detection circuit further includes:
a calibration capacitor, having one end coupled to the output end of the receiver;
a first calibration switch, coupled between the other end of the calibration capacitor and a first calibration voltage, wherein a conduction state of the first calibration switch is synchronized with the first switch; and
a second calibration switch, coupled between said the other end of the calibration capacitor and a second calibration voltage, wherein a conduction state of the second calibration switch is synchronized with the second switch.
10 . The detection circuit according to claim 1 , wherein the positive end of the operational amplifier is coupled to a third calibration voltage.
11 . The detection circuit according to claim 1 , wherein the received signal includes a plurality of sinusoidal waves or triangular waves having a period of T.
12 . The detection circuit according to claim 1 , further comprising:
a control circuit, configured to generate the followings according to a reference clock:
a first control signal to control the first switch;
a second control signal to control the second switch;
a reset signal to control the reset switch; and
a third control signal to control a transmitter to generate an output signal, wherein the third control signal is periodic and has a period of T, wherein the output signal passes through a channel and then becomes the input signal that enters the receiver.
13 . The detection circuit according to claim 12 , wherein the transmitter includes a first transducer, and the receiver includes a second transducer.
14 . The detection circuit according to claim 1 , further comprising:
a control circuit, configured to generate the followings according to the received signal:
a first control signal to control the first switch;
a second control signal to control the second switch; and
a reset signal to control the reset switch.
15 . An electronic apparatus, comprising:
the detection circuit according to claim 1 .