AC level calibration method and apparatus

Claim 3

A method of AC level calibration in an analog test system for integrated circuits, as recited in claim 1, wherein said forming step is performed by utilizing the control signal to alternately open and close first and second switches, the first switch being connected to the DC reference voltage, and the second switch being connected to ground.

Claim 4

A method of AC level calibration in an analog test system for integrated circuits, as recited in claim 2, wherein said forming step comprises forming a rectangular waveform signal as the AC level calibration signal.

Claim 5

A method of AC level calibration in an analog test system for integrated circuits, as recited in claim 1, wherein said processing step is performed by performing a fast Fourier transform on the digital signal.

Claim 6

A method of AC level calibration in an analog test system for integrated circuits, as recited in claim 4, wherein said forming step is performed by utilizing the control signal to alternately open and close first and second switches, the first switch being connected to the DC reference voltage, and the second switch being connected to ground.

Claim 7

A method of AC level calibration in an analog test system for integrated circuits, as recited in claim 5, wherein said forming step comprises forming a rectangular waveform signal as the AC level calibration signal.

Claim 8

A method of AC level calibration in an analog test system for integrated circuits, as recited in claim 1, wherein said processing step is performed by performing a discrete Fourier transform on the digital signal.

Claim 9

A method of AC level calibration in an analog test system for integrated circuits, as recited in claim 7, wherein said forming step is performed by utilizing the control signal to alternately open and close first and second switches, the first switch being connected to the DC reference voltage, and the second switch being connected to ground.

Claim 10

A method of AC level calibration in an analog test system for integrated circuits, as recited in claim 8, wherein said forming step comprises forming a rectangular waveform signal as the AC level calibration signal.

Claim 11

An analog test system, including a DC power source for generating a DC reference voltage, and a digital signal generator for generating an alternating control signal which is a first level signal for a first time period, and a second level signal for a second time period, characterized in that said analog test system comprises: an analog switching device, coupled to an output of said DC power source and an output of said digital signal generator, for interrupting the flow of the reference voltage based on the alternating control signal generated by said digital signal generator and for changing the reference voltage into an AC level calibration signal waveform; a waveform digitizer, coupled to said analog switching device, for converting the AC level calibration signal into a digital data signal; digital signal processing means, coupled to said waveform digitizer, for obtaining reference values from the digital data signal; comparing means for comparing said reference values from the digital data signal with predetermined reference values and for obtaining an AC level error; and compensating means for calibrating for said AC level error.

Claim 12

An analog test system, including a DC power source for generating a DC reference voltage, and a digital signal generator for generating an alternating control signal which is a first level signal for a first time period, and a second level signal for a second time period, characterized in that said analog test system comprises: an analog switching device, coupled to an output of said DC power source and an output of said digital signal generator, for interrupting the flow of the reference voltage based on the alternating control signal generated by said digital signal generator and for changing the reference voltage into an AC level calibration signal waveform; a waveform digitizer, coupled to said analog switching device, for converting the AC level calibration signal into a digital data signal; digital signal processing means, coupled to said waveform digitizer, for obtaining reference values from the digital data signal; comparing means for comparing said reference values from the digital data signal with predetermined reference values and for obtaining an AC level error; and compensating means for calibrating for said AC level error.

Claim 13

An analog test system according to claim 10, wherein said analog switching device further comprises: a first analog switch coupled between said DC power source and said waveform digitizer; a second analog switch coupled between ground and said waveform digitizer; and a switch circuit connected to said digital signal generator for controlling said first and second switches based on the alternating control signal from said digital signal generator, wherein upon receiving the first level signal, said switch circuit closes said first analog switch, connecting said power source to said waveform digitizer and allowing the reference voltage to flow to said digitizer, and wherein upon receiving the second level signal, said switch circuit opens said first analog switch and closes said second analog switch, connecting said waveform digitizer to ground.

Claim 14

An analog test system according to claim 11, wherein said drive switch circuit further comprises a capacitor coupled between said power source and said first analog switch, for excluding spikes from said first analog switch.

Claim 15

An analog test system according to claim 10, wherein said digital signal processing means comprises means for performing a fast Fourier transform on the digital data signal.

Claim 16

An analog test system according to claim 10, wherein said digital signal processing means comprises means for performing a discrete Fourier transform on the digital data signal.

Claim 17

A circuit for AC level calibration in an analog test system including a power source, a waveform digitizer, and a digital signal generator for generating a control signal, characterized in that said circuit comprises: a first analog switch coupled to the power source and the waveform digitizer; a second analog switch coupled to the waveform digitizer and the ground; and a switch circuit connected for controlling said first and second analog switches, said switch circuit alternately opening and closing said first and second analog switches based on the control signal from the digital signal generator, so that an AC level calibration signal is sent to the waveform digitizer.

Claim 18

A circuit for AC level calibration in an analog test system including a power source, a waveform digitizer, and a digital signal generator for generating a control signal, characterized in that said circuit comprises: a first analog switch coupled to the power source and the waveform digitizer; a second analog switch coupled to the waveform digitizer and the ground; and a switch circuit connected for controlling said first and second analog switches, said switch circuit alternately opening and closing said first and second analog switches based on the control signal from the digital signal generator, so that an AC level calibration signal is sent to the waveform digitizer.

Claim 19

A circuit for AC level calibrating in an analog test system according to claim 15, wherein the AC level calibration signal is a rectangular waveform.

Claim 20

A circuit for AC level calibration in an analog test system according to claim 16, further comprising a capacitor, coupled between said first analog switch and the power source, for excluding spikes from said first analog switch.