Single Sideband Up-Conversion Mixer
Sam Johnson and Travis Watson
Purpose
The frequency synthesizer generates a data stream that modulates the Low Frequency Oscillator, producing a frequency modulated signal at the Intermediate Frequency (IF). The Mixer multiplies the IF and Local Oscillator (LO) waveforms, which up-converts the IF to the transmit frequency, as shown below.
Full Schematic
View the schematic for each block
Layout and Testing
The quadrature phase generator and mixer were produced using the Unix program MAGIC. The complete testing design, including probe pads and test points, is included below. Click on the thumbnail for a full view. The table lists all the probe pads and their use in testing, as well as a more in-depth explanation of the analog probe pads.
Magic Layout
| Test Point | Desciption |
| 1 | 2.0 Volt DC Bias of High Frequency Phase Generator Input |
| 2 | 2.4 Volt DC Bias of the Mixer Core |
| 3 | 1.2 Volt DC Bias of the Mixer Core |
| 4 | 1.5 Volt DC Bias of Low Frequency Phase Generator Input |
| 5 | Full Mixer Positive Output Bus. Contains Buffer Driver Circuitry. |
| 6 | Full Mixer Negative Output Bus. Contains Buffer Driver Circuitry. |
If you're really interested, the MAGIC layout files can be found here.
Once the layout was complete, Layout Versus Schematic (LVS) was done to verify that is was indeed laid out correctly. MAGIC can only extract transistors and capacitors; the resistors and sources were added manually. This was run on the entire design, including the mixer core and phase generators. The outcome is promising, with voltages and upper sideband suppression resembling the original design and HPADS simulations. Please visit the mixer core section to view the final LVS.