AnsweredAssumed Answered

XORing analog RF with digital signal using HMC745

Question asked by Hussain on Aug 16, 2016
Latest reply on Aug 16, 2016 by salemdar

Dear Sir! I am a student and want to use HMC745 for a low-delay XOR operation, i.e., just as an XOR gate. My goal is to prototype a basic XOR circuit for Cryptology (Encryption) application, in which I want to XOR the 13 MHz CW (analog) RF signal directly with digital bits (up to 100 kbps).. In my application, according to standard XOR convention:

- The input sources D0 and D1, as well as the output Q, are single-ended.

- Input D0 is a Continuous Wave RF signal at 13 MHz which comes from an NFC antenna, while input D1 is digital signal coming from a microcontroller within 10-100 kbps.

- There is no specific fan-in and fan-out... The RF input (D0) directly comes from NFC antenna. The digital input (D1) comes from a micro-controller (MCU). The output (XORed-RF signal) will be fed to another NFC antenna directly. If any change in circuit design is required, i can easily do it in the PCB, like AC/DC coupling, digital voltage (D1) or RF level (D0) conversion, pullup or down, etc


I need your kind guidance for:

1) Will HMC745 properly XOR the 13 MHz analog RF signal with 100 kbps digital signal?

2) If i give D0 and D1 signals at AP and BP pins of HMC745, then unused pins should be pulled up to Vcc with 50Ohm, or, i should leave them floating (as they are internally pulled up)? Similarly, what about unused output pin (DN)?

3) I assume that i should make my prototype circuit according to the schematic in the datasheet of HMC745LC3. Will the power supply bypass capacitors remain same at my low frequency range of 13MHz? My question pertains to C1-C5 capacitors in said document.

4) Lastly, the VR functionality will work for XORed analog RF (at DP pin), or, will it DC-bias the RF?


Thanks in advance for your valuable comments!!