Use the IQ Modulator block to Modulate a two-tone DC signal to RF level. Observe the impairments in the modulated output signal such as images due to gain imbalance, intermodulation distortion, and output third-order intercept (OIP3).
The two tones are at 10MHz and 15 MHz.The power of each tone is -30 dBm. The carrier frequency is 0 GHz.
The IQ modulator parameters are :
Available power gain: 10 dB
Local oscillator frequency: 2 GHz
I/Q gain mismatch: 0.1 dB
LO to RF Isolation: 90 dB
Noise Floor: -160 dBm/Hz
IP3: 10 dBm
Open the model.
Run the model and observe the spectrum analyzers.
In the complex output power density spectrum analyzer, you see the noise floor of the signal at -160 dBm/Hz.
In the complex output spectrum analyzer, you see the whole modulated signal including the imaginary parts. The output power level of the two tones (10 MHz and 15 MHz)is -20 dBm.
The output third-order intercept( OIP3) is at 10 dBm. The spectrum analyzer measures this value.
The images of the two tones are at -10 MHz and -15 MHz. The output power level of the two images are -67.8 dBm. Image rejection ratio is given by the formula:
The image power level is given by the formula: