Mixers & Frequency Conversion

1. Conceptual Intuition (L1)

• Magic multiplication: Moving signals up (Tx) or down (Rx) the spectrum.
• The fundamental math: $\sin(A) * \sin(B) = 0.5[\cos(A-B) - \cos(A+B)]$.
• Sum and Difference frequencies.

2. Engineering Math (L2)

• Port definitions: RF, LO, IF.
• Conversion Loss (Passive) vs Conversion Gain (Active).
• Image Frequencies and why we need filters before mixers.

3. System Application (L3)

• Linearity: 1dB Compression and IP3 in mixers.
• LO Leakage and DC Offset (Zero-IF issues).
• Spurious products table ($M \times RF \pm N \times LO$).

Interactive Component: Spectral Spur Viewer

• Description: See where the spurs land.
• Controls: RF Freq, LO Freq, Mixer Type.