trashbox
Advanced Member level 4
Hi all,
The attached figure is MAXIM2743's(it is a VCO buffer amplifier) typical operating circuit from its datasheet, I am very puzzled about it:
1) There is no impedance match between vco output and MAXIM2743 input,it seems that it is in order to suppress vco's pulling effect. So my puzzle is:what is the major factor which causes pulling effect? Why can the MAXIM2743's large input resistor suppress vco pulling effect?
2) There are L_match and C_match in order to do the impedance match at the MAXIM2743's output since its datasheet provides MAXIM2743's S11,S12,S21,S22. My puzzle is:if I want to match the MAXIM2743 output into 50 ohm, How can I do according to the provided S-parameter? I can get Z1 based on S11,Z2 based on S12,Z3 based on S21 and Z4 based on S22 according to the definition. So how to select and understand the relation between Zout(that I want to match into 50 ohm) and S-parameter?
Thank you very much!
The attached figure is MAXIM2743's(it is a VCO buffer amplifier) typical operating circuit from its datasheet, I am very puzzled about it:
1) There is no impedance match between vco output and MAXIM2743 input,it seems that it is in order to suppress vco's pulling effect. So my puzzle is:what is the major factor which causes pulling effect? Why can the MAXIM2743's large input resistor suppress vco pulling effect?
2) There are L_match and C_match in order to do the impedance match at the MAXIM2743's output since its datasheet provides MAXIM2743's S11,S12,S21,S22. My puzzle is:if I want to match the MAXIM2743 output into 50 ohm, How can I do according to the provided S-parameter? I can get Z1 based on S11,Z2 based on S12,Z3 based on S21 and Z4 based on S22 according to the definition. So how to select and understand the relation between Zout(that I want to match into 50 ohm) and S-parameter?
Thank you very much!