Cyclic A/D converter
A converter and conversion circuit technology, applied in the direction of analog-to-digital converter, analog-to-digital conversion, code conversion, etc., can solve problems such as increased circuit area and power consumption
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no. 1 example
[0024] Refer below figure 1 -4 to describe the cyclic A / D converter according to the first embodiment.
[0025] figure 1 Shown is a capacitive acceleration sensor having a sensor element 1 and used for on-board control and a cyclic A / D converter 2 configured to A / D convert an output signal of the capacitive acceleration sensor integrated circuits (ICs). The sensor element 1 of the capacitive acceleration sensor has capacitors CE1 and CE2. Capacitance of capacitors CE1 and CE2 is CE when no acceleration is applied. The capacitors CE1 and CE2 complementarily change their respective capacitances according to the acceleration applied thereto. For example, when the capacitance of capacitor CE1 increases by ΔC / 2, the capacitance of capacitor CE2 decreases by ΔC / 2. Capacitors CE1 and CE2 are connected to terminals FE1 and FE2, respectively. Driving voltages Vsp and Vsm are alternately applied to terminals FE1 and FE2. Capacitors CE1 and CE2 are connected to each other and to t...
no. 2 example
[0064] next reference Figure 5 To describe the cyclic A / D converter according to the second embodiment, in Figure 5 The same or similar reference numerals are used for the same or similar components as those in the first embodiment.
[0065] In the first embodiment, the cyclic A / D converter 2 performs A / D conversion after C / V converting the signal charge Sin and then amplifying the C / V converted voltage. In the case where the voltage output as a result of the C / V conversion of the signal charge Sin is already suitable for the dynamic range of the A / D conversion, the amplification operation in the first embodiment can be eliminated. According to the second embodiment, the cyclic A / D converter 2 is configured to perform A / D conversion of a voltage output by C / V conversion of the signal charge Sin.
[0066] (1) C / V conversion operation
[0067] Such as Figure 5 As shown, before the A / D conversion operation, the control circuit 8 performs a C / V conversion operation (samplin...
no. 3 example
[0073] next reference Figure 6 and 7 to describe the cyclic A / D converter according to the third embodiment, in Figure 6 The same or similar reference numerals are used for the same or similar parts in 7 and the first embodiment.
[0074] According to the third embodiment, as Figure 6 As shown, the detection current Iin is input from the exhaust gas sensor 21 to the cyclic A / D converter 2 through the signal input terminal 3 . The exhaust gas sensor 21 is configured to output, for example, a function of NO remaining in the exhaust gas of the vehicle engine x Detection current Iin of concentration change. The current represents the amount of charge flowing per unit time. The detection charge Iin thus corresponds to the external signal charge.
[0075] The cyclic A / D converter 2 I / V-converts the detection current Iin by using the switching circuit 5, the multiplying D / A converter 6, etc., and then amplifies the converted voltage. 6 etc. are initially and usually set for ...
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