Demonstration circuit 2524A is optimized for evaluation of the LTC5555 programmable gain downconverting mixer. The IC incorporates an active mixer and a digital IF VGA with 15.5dB gain control range. The IF gain is programmed in 0.5dB steps through the SPI or parallel interface. The LTC5555 has single-ended 50Ω RF input, single-ended or differential-drive LO input, and differential IF output. It features an enable pin for fast turn-on and shutdown. A reduce power mode is also available through SPI or a CMOS logic pin reducing the total current consumption by approximately 25%.
Demonstration circuit 2524A’s RF input port is 50Ω matched from 2.6GHz to 6.4GHz and can be easily tuned down to 1.5GHz or up to 7GHz. The LO port is 50Ω matched from 500MHz to 7GHz. The demo circuit’s differential IF outputs has 100Ω differential impedance and are match for 115MHz to 495MHz IF frequencies. The IF outputs can be modified for other IF frequencies or impedances. Transformer footprint pads are included on the PCB allowing the use of IF transformer to provide 50Ω single-ended IF output. See data sheet for more details on input and output impedance matching.
CAUTION: This part is sensitive to electrostatic discharge (ESD). Observe proper ESD precautions when handling the LTC5555.