Self calibration method for radio equipment with receive and transmit circuitry
A self-calibration circuit for testing an RF device includes the RF device to be tested having transmit and receive sections, and a built-in self test (BIST) circuit coupled to the transmit and receive sections of the RF device on the same chip. The self-calibration circuit is configured to calibrate the receive section of the RF device in a receive test mode, and calibrate the transmit section of the RF device in a subsequent transmit test mode using the calibrated receive section to measure a transmit output signal from the transmit section and to provide calibration data therefrom used in the transmit section calibration. The self-calibration circuit may include a duplex filter coupled between the transmit and receive sections and the BIST circuit, and a multiplexor coupled between the RF device, and the BIST circuit, configured to select one or more of a plurality of RF devices to be tested.
1. A self-calibration circuit for testing an RF device, comprising:
the RF device to be tested having transmit and receive sections; and
a built-in self test (BIST) circuit coupled to the transmit and receive sections of the RF device on the same chip, configured to
calibrate the receive section of the RF device in a receive test mode, and
calibrate the transmit section of the RF device in a subsequent transmit test mode using the calibrated receive section to measure a transmit output signal from the transmit section and to provide calibration data therefrom used in the calibration of the transmit section.
2. The self-calibration circuit of claim 1 , wherein the BIST circuit further comprises an RF signal generator configured to generate an RF signal to an input of the receive section by way of a high pass filter.
3. The self-calibration circuit of claim 2 , wherein the high pass filter is coupled to the RF signal, the transmit output signal of the transmit section and an input of the receive section, is configured to provide isolation between the transmit output signal of the transmit section and the RF signal generator, to suppress unwanted mixing products in the RF signal, and to generate a filtered RF signal.
4. The self-calibration circuit of claim 2 , wherein the BIST circuit further comprises a mixer coupled to the RF signal generator, and the transmit output signal of the transmit section and the input of the receive section, configured to generate a wanted signal equivalent to the nominal frequency of the receiver by mixing the transmit output signal with the RF signal from the RF signal generator tuned to a frequency equivalent to the duplex separation in the RF device for the transmit section calibration in the transmit test mode.
5. The self-calibration circuit of claim 4 , wherein the BIST circuit further comprises a first power splitter coupled between the signal generator, the mixer, and the high pass filter, configured to split the RF power from the signal generator between the mixer and the high pass filter, and to suppress undesired mixing products.
6. The self-calibration circuit of claim 5 , wherein the BIST circuit further comprises a second power splitter coupled between an input and an output of the mixer, the high pass filter and the RF device to be tested.
7. The self-calibration circuit of claim 6 , wherein the first power splitter is a three port power splitter and the second power splitter is a four port power splitter.
8. The self-calibration circuit of claim 1 , wherein the transmit output signal measured by the calibrated receive section is transmitted from the transmit section.
9. The self-calibration circuit of claim 1 , wherein the RF device to be tested further comprises a duplex filter coupled between the transmit output signal from the transmit section and the input of the receive section, and the BIST circuit.
10. The self-calibration circuit of claim 9 , wherein the BIST circuit further comprises a multiplexer coupled between the duplex filter of the RF device, and the BIST circuit, configured to select one or more of a plurality of RF devices to be tested.
11. A self-calibration circuit, comprising:
an RF device to be tested having transmit and receive sections;
a built-in self test (BIST) circuit coupled to an output of the transmit section and an input of the receive sections of the RF device on the same chip, configured to
calibrate the receive section of the RF device in a receive test mode, and
calibrate the transmit section of the RF device in a transmit test mode using the calibrated receive section to measure a transmit output signal from the transmit section and to provide calibration data therefrom, the BIST circuit comprising
an RF signal generator configured to generate an RF signal;
a high pass filter coupled to the RF signal from the RF signal generator, the transmit output signal from the output of the transmit section and the input of the receive section, configured to provide isolation between the transmit output signal from the transmit section and the RF signal from the RF signal generator, to suppress unwanted mixing products in the RF signal, and to generate a filtered RF signal; and
a mixer coupled between the RF signal generator, the output of the transmit section and the input of the receive section, configured to generate a wanted signal equivalent to the nominal frequency of the receiver by mixing the transmit output signal with the RF signal from the RF signal generator having a frequency equivalent to a duplex separation in the RF device.
12. The self-calibration circuit of claim 11 , wherein the BIST circuit further comprises a first power splitter coupled between the signal generator, the mixer, and the high pass filter, configured to split the RF power from the RF signal generator between the mixer and the high pass filter, and to suppress undesired mixing products.
13. The self-calibration circuit of claim 12 , wherein the BIST circuit further comprises a second power splitter coupled between an input and an output of the mixer, the high pass filter and the duplex filter.
14. The self-calibration circuit of claim 11 , wherein the calibration of the transmit and receive sections of the RF device is accomplished in one of an open loop mode wherein a user selects from among a plurality of BIST testing algorithms or test sequences, a closed loop mode wherein the BIST circuit selects from among a plurality of BIST testing algorithms or test sequences to be accomplished, a closed loop mode wherein the BIST circuit runs one or more predetermined tests, and a combination of the open and closed loop modes.
15. The self-calibration circuit of claim 11 , wherein the transmit output signal measured by the calibrated receive section is transmitted from the transmit section.
16. The self-calibration circuit of claim 11 , wherein the RF device to be tested further comprises a duplex filter coupled between the transmit output signal of the transmit section and the input of the receive section, and the BIST circuit.
17. The self-calibration circuit of claim 16 , wherein the BIST circuit further comprises a select switch coupled between the duplex filter of the RF device, and the BIST circuit, configured to select one or more of a plurality of RF devices to be tested.
18. The self-calibration circuit of claim 11 , wherein the RF device utilizes one of a UMTS, CDMA, WDCMA, GSM and 3GSM standard.