LTC5562 ACTIVE MIXER UP AND DOWN CONVERTER SCHEMATIC REVIEW

Hello,

We would need to know if the intended application needs either Single Ended Input or Differential Input and Single Ended Output or Differential Output. Assuming you are using Single Ended Input and Single Ended Output as shown in the datasheet, the use of a capacitor between the the differential input pins looks correct to improve return loss at higher frequencies for differential inputs(In Downcoverting case). The combinations of the Transformers used in the schematic above would yield different results than specified in the datasheet as the Impedance Ratio of the transformers for both Upconverter Application and Downconverter application looks to be different. For the above specified applications below are the recommended transformers that were used for characterizing the performance of the mixer LTC5562 as specified in the datasheet.

Upconverting Mixer:

IF Transformer: TC1-1-13M+

RF Transformer: NCS4-63+ 

The IF transformer yields good input return loss for the specified application and the RF Transformer helps yields good better results for single ended output.

Downcoverting Mixer:

RF Transformer: TCM1-83X+

IF Transformer: TCM4-19

Again the RF Transformer gives good return loss for the Input signals and the IF transformer giver lower amplitude imbalance and better overall result at the intended Single Ended output.

Please Refer to pages 12 and 13 in the datasheet for Upconverting and downconverting application designs.

Thanks.

Hello,

We would need to know if the intended application needs either Single Ended Input or Differential Input and Single Ended Output or Differential Output. Assuming you are using Single Ended Input and Single Ended Output as shown in the datasheet, the use of a capacitor between the the differential input pins looks correct to improve return loss at higher frequencies for differential inputs(In Downcoverting case). The combinations of the Transformers used in the schematic above would yield different results than specified in the datasheet as the Impedance Ratio of the transformers for both Upconverter Application and Downconverter application looks to be different. For the above specified applications below are the recommended transformers that were used for characterizing the performance of the mixer LTC5562 as specified in the datasheet.

Upconverting Mixer:

IF Transformer: TC1-1-13M+

RF Transformer: NCS4-63+ 

The IF transformer yields good input return loss for the specified application and the RF Transformer helps yields good better results for single ended output.

Downcoverting Mixer:

RF Transformer: TCM1-83X+

IF Transformer: TCM4-19

Again the RF Transformer gives good return loss for the Input signals and the IF transformer giver lower amplitude imbalance and better overall result at the intended Single Ended output.

Please Refer to pages 12 and 13 in the datasheet for Upconverting and downconverting application designs.

Thanks.