Garyl
Full Member level 5
Hey,
Recently I've looked more into the receivers theory and schematics and found out that digital DDS are getting more popular these days.
I've seen simple PIC projects for AD9835, but I will most likely use AD9834 because it seems more accessible in the online store I buy.
From AD9834 datasheet:
AD9834 internal block diagram:
The receiver I work on schematic is here:
I'd like to replace the tuning circuit with potentiometer and varicap and use the PIC/Arduino/PC to set the frequency in a digital way. Maybe by UART, USB or simply buttons attached to MCU and LCD.
My question is, is AD9834 suitable to be used instead of VFO? What would be pros and cons of using it there? And if yes, then how exacly do I connect AD9834 output to MC3361? MC3361 has two input pins to the mixer (called "oscillator pins" in the datasheet), and AD9834 has two output pins, but what about the capacitors those pins, and ground, and VCC?
Recently I've looked more into the receivers theory and schematics and found out that digital DDS are getting more popular these days.
I've seen simple PIC projects for AD9835, but I will most likely use AD9834 because it seems more accessible in the online store I buy.
From AD9834 datasheet:
The AD9834 is a 75 MHz low power DDS device capable of
producing high performance sine and triangular outputs. It also
has an on-board comparator that allows a square wave to be
produced for clock generation. Consuming only 20 mW of power
at 3 V makes the AD9834 an ideal candidate for power-sensitive
applications.
Capability for phase modulation and frequency modulation is
provided. The frequency registers are 28 bits; with a 75 MHz clock
rate, resolution of 0.28 Hz can be achieve
AD9834 internal block diagram:
The receiver I work on schematic is here:
I'd like to replace the tuning circuit with potentiometer and varicap and use the PIC/Arduino/PC to set the frequency in a digital way. Maybe by UART, USB or simply buttons attached to MCU and LCD.
My question is, is AD9834 suitable to be used instead of VFO? What would be pros and cons of using it there? And if yes, then how exacly do I connect AD9834 output to MC3361? MC3361 has two input pins to the mixer (called "oscillator pins" in the datasheet), and AD9834 has two output pins, but what about the capacitors those pins, and ground, and VCC?
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