REP023: Upconverter from 350MHz to 3.5GHz with 9dB gain and 1.3dBm IIP3

Rapid engineering prototypes are actual circuits that Maxim application engineers build in the lab and conduct product testing. They are the starting point for new RF engineering designs. They are not intended to be used as assessment testing tools.

Goal: Develop a circuit using this downconverter IC as an upconverter.

The MAX2683 is used here as an upconverter and its performance was tested in the 350MHz IF input band (via the RF input pin). Using a local oscillator frequency to 2.0GHz, the observed output was 3.55GHz (from the differential IF output pin). ). The output is converted using a balun and connected to a 50Ω transmission line. The measured upconversion gain is close to 9dB and the linearity is IIP3 of +1.3dBm. A set of S parameters was referenced when designing the matching network. This application circuit was considered a complete success.

MAX2683 is a high-performance, low-power downconverter designed for the receive channel of 3.5GHz wireless data transceiver. It has 6dB conversion gain, variable IIP3 up to 11dBm, IF input range from 100MHz to 400MHz, and conversion output of 3.5GHz, using a low-end LO (approximately 2.7GHz). The MAX2683 has an LO frequency multiplier that is used when inputting ½ the local oscillator frequency and can switch between basic mode and multiplier mode. The MAX2683 operates with a minimum operating voltage of 2.7VDC and is packaged in a 16-pin TSSOP.

Schematic for upconverter application (PDF, 34kB)
PCB layout plots
Bill of materials
Measurement test setup
S11 LOG MAG of RF IN input match results with V_CC = 3.3V
S11 LOG MAG of RF LO input match results with V_CC = 3.3V
S11 LOG MAG of mixer's differential output matching results with V_CC = 3.3V
S11 LOG MAG of RF IN input match results with V_CC = 5.0V
S11 LOG MAG of RF LO input match results with V_CC = 5.0V
S11 LOG MAG of mixer's differential output matching results with V_CC = 5.0V