RECEIVER SYSTEM AND METHOD FOR RECEIVER TESTING
A receiver system which may be implemented in an integrated circuit device and suitable for use in automotive radar systems such as collision avoidance systems, includes self test circuitry whereby a local oscillator test signal is generated by an on-board frequency multiplier and mixed in a down-conversion mixer with an RF test signal. The RF test signal is generated on the device by up-conversion of an externally generated low-frequency test signal with the local oscillator test signal. Baseband components may also be checked using test signals of suitable frequency divided down from the local oscillator test signal by a programmable frequency divider. This self test arrangement obviates any need for applying externally generated RF test signals to the IC device.
1 . A receiver system comprising:
a down-conversion mixer;
a frequency multiplier configured to generate a local oscillator test signal;
a first coupler configured to couple the local oscillator test signal to a first input of the down-conversion mixer;
an input port configured to receive a test signal;
an up-conversion mixer configured to mix the received test signal with the local oscillator test signal to produce an RF test signal;
a second coupler configured to couple the RF test signal to a second input of the down-conversion mixer; and
an output port configured to receive a baseband signal from an output of the down-conversion mixer.
2 . The receiver system of claim 1 wherein the frequency multiplier comprises a phase-locked loop.
3 . The receiver system of claim 2 wherein the phase-locked loop is configured to be driven by a SPI (serial peripheral interface) clock signal.
4 . The receiver system of claim 1 wherein the frequency multiplier is configured to be driven by a SPI (serial peripheral interface) clock signal and arranged to multiply the SPI clock signal by harmonic multiplication.
5 . The receiver system of claim 1 further comprising:
a baseband module arranged between an output of the down-conversion mixer and the I F output port; and
a programmable frequency divider operably coupled to the output of the frequency multiplier and configured to generate baseband test signals for applying to the baseband components.
6 . The receiver system of claim 5 further comprising a switch configured to divert the received test signal to either the up-conversion mixer or to the baseband module.
7 . The receiver system of claim 1 implemented in an integrated circuit
8 . A method for testing a receiver, the method comprising:
generating in the receiver a local oscillator test signal using a frequency multiplier;
coupling the local oscillator test signal to a first input of a down-conversion mixer;
receiving a test signal at an input port of the receiver;
up-converting the received test signal with the local oscillator test signal in an up-conversion mixer to produce an RF test signal;
coupling the RF test signal to a second input of the down-conversion mixer; and
mixing the RF test and local oscillator test signals in the down-conversion mixer to produce a baseband signal at an output port of the receiver.
9 . The method of claim 8 comprising:
dividing the local oscillator test signal to produce lower frequency test signals; and
applying said lower frequency test signals to baseband components of the receiver
10 . The method of claim 9 wherein dividing the local oscillator test signal is performed in a programmable frequency divider
11 . The method according to claim 8 wherein the frequency multiplier comprises a phase-locked loop.
12 - 15 . (canceled)