LT5560 component :0.01MHz to 4GHz Low Power Active Mixer......

.Please tell me the impedance of LO input at 10MHz and also the value of the components(C3,C4,C5,L5) required for the  reactive matching at this frequency

  • Hello,

    When you start getting down to such low frequencies, the LO input impedance is mostly characterized by the internal resistors shown in Figure 7 on page 17 of the datasheet. For this part, the LO input impedance at 10MHz is going to be in the neighborhood of 160Ω.

    It can be difficult to get a reactive match at 10MHz, so we would typically just use a resistive match with a DC block as is shown in Figures 21 and 22 on pages 24 and 25 of the datasheet. Using 160Ω for the resistor will give you roughly 10dB return loss at 10MHz. You can decrease the resistor's value to improve the match, if necessary. Note that you may need to increase the LO drive slightly to maintain the performance since some signal power will be lost in the resistor. You can play with your LO drive level to see what gives you the performance you require.

    Best regards,

    Weston Sapia

  • Thanks for replying....I really appreciate you answered my query...just one more doubt

    How can i simulate this mixer with all this external components (resistors,capacitors and inductors)? I'm not able to find a spice model for LT5560 mixer. 

  • Typically, RF components are simulated using s-parameters and signal chain characteristics (gain, IP3, NF, etc.), not their time-domain characteristics.

    To do this, you would use an RF simulator such as ADS or QUCS for the s-parameters, and any number of programs to do a signal chain analysis. One that I like to use is AppCad.

  • Thanks for the information.

    For my application the signal output port(Pin 5&6) frequency range is from 1KHz to 20KHz, so according to Table7 & Figure 3 its working for 10MHz with L3=L4=0 i.e. no external component is required, only transformer is required for impedance matching.

    So, "will this configuration work for 1KHz-20KHz (much lower frequency) output"

    No information is available for such lower frequency IF output in the datasheet.