Linear Technology LT5515 Board Level Design Issues and Considerations Handbook

About this manual

The document addresses critical performance degradation factors in direct conversion receiver designs, specifically focusing on Local Oscillator (LO) leakage to Baseband outputs and RF/LO ports. It provides suggested actions such as using high frequency terminations, routing signal lines on the bottom side of the PCB, and utilizing solid ground planes with extensive vias.

What's inside

• Board level issues
• LO leakage to Baseband
• RF leakage to BB outputs
• LO leakage to RF input
• RF leakage to LO port
• Parts placement issues
• Bypass capacitors
• Transformer coupling minimization
• PCB layout considerations

Specifications

Frequently asked questions

What causes degradation of phase balance in baseband I/Q signals?

LO leakage to the BB outputs, as well as the second harmonic of LO at the BB outputs.

How should bypass capacitors be placed on the PCB?

They should be placed as closely as possible to the designated Vcc pins of the IC.

What is the recommended distance between the RF input transformer and the LT5515 package?

The RF input transformer should be placed about 4.0mm away from the side of the LT5515 package where the RF input pins are located.