ADL5350: Improve conversion loss

Question I want to use ADL5350. According to my test, the conversion loss is more than 10dB, much larger than the spec in datasheet. Would you please help review it and give some suggestions on how to improve the performance? Thanks to you help in advance. Answer I advise to follow the IMPLEMENTATION PROCEDURE on ADL5350 data sheet (page 17-18), and tune the RF/IF/LO networks accordingly. In general, the RF and LO input ports should be designed to pass the RF or LO signals, while the IF output port should be designed to block RF and LO frequencies. It looks like the customer misunderstood how this mixer works, and is simply using coupling caps of 4.7nF on all three ports, which is not going to meet the design requirements. With that being said, for each different frequency plans, customers would need to set up the tuning networks for frequency specific. The same principle applies to both receive (RX) and transmit (TX) applications, which also means the networks tuned for receiving will NOT work for transmitting within the same frequency plan. For instance, 125MHz IN with 50MHz in RX should have different external networks from ones serving 50MHz IN with 125MHz OUT in TX. You may want to find out what application is this, and if this is for TX, RX or both. If it is for RX, then you can easily pick Figure 59 as a start point, and tune the networks (lower L or/and C values a bit in 36nH and 27pF combo) on both sides, so that the tuning is optimized for 125MHz input frequency. If it is for TX, then you need to start over by following our procedure for 50MHz input frequency. If you’re interested to test this frequency band, they should use the schematic provided in Figure 65 (Board A) on ADL5350 data sheet. Last, the mixer is not sensitive to RF/IF INPUT power levels, so it is not meaningful to sweep the input power levels when debugging. Sweeping LO power levels for seeking improved conversion loss might be a good idea (see Figure 23) only after the external networks are properly tuned for desired frequency bands, otherwise I would suggest to leave LO at 4 dBm as default.

ADL5350's S-parameter

Question Do you have the s parameter of ADL5350? Answer We do not attempt to measure s-parameters on passive mixers. We try to include enough examples in the datasheet so that you can tweak examples to agree with their frequency plan. Even if we had valid s-parameters on the part I don't believe it would make the job any easier. The passive mixer core should be thought of as a switch. With a single-ended passive mixer the presented impedance on the RF and IF ports at the device are changing from a low RDS value to several kOhms as the LO signal switches the core. If we tried to measure the RFIF impedance on a network analyzer we would end up measuring the on resistance, off resistance, or some transition value. Any of the three would not help you match to the RFIF nodes. The real game here is designing the off-chip LC networks so that the RF network provides minimum reflection at the RF frequency, and the IF port provides minimum reflection at the IF frequency. Simultaneously we are trying to maximize port isolation and optimize conversion loss, NF and IP3. In general we are always trying to find a reasonable compromise between all these parameters.

ADL5350's Frequency Range

Question I have a question about ADL5350. As below figure shown, ADL5350 can be operated from LF to 4GHz. Would you please tell me what's the "LF"'s Value? Is it several MHz or several kHz? Answer In theory this mixer should be able to support down to kHz range, but we don’t have any data due to very little demand.