Technical characteristics and internals of NanoVNA.

NanoVNA Technical Specifications and Hardware Architecture

The hardware of the NanoVNA represents a masterpiece of cost optimization. The developers managed to achieve excellent radio frequency (RF) parameters based on accessible and inexpensive general-purpose radio components.

Technical Specifications of the Classic NanoVNA

Device Parameter	Technical Specifications of NanoVNA V1
Frequency Range	50 kHz – 300 MHz (base), up to 900 MHz (harmonic mode), up to 1500 MHz (extended)
Number of Scan Points	101 points (fixed hardware limitation in internal memory)
RF Output (Port CH0)	-13 dBm nominal (maximum up to -9 dBm) into a 50 Ohm load
S21 Dynamic Range	70 dB (50 kHz – 300 MHz), 50 dB (300 – 600 MHz), 40 dB (600 – 900 MHz)
Measurement Port SWR	< 1.1 across the entire working frequency range
Frequency Error	< 2.5 ppm (reference oscillator frequency stability < 0.5 ppm)
Device Display	2.8 inches, TFT, resistive touchscreen, 320 x 240 pixel resolution
Communication & Power Interface	USB Type-C, USB CDC class (virtual COM port)
Built-in Battery	Lithium-polymer, 3.7 V, capacity ranging from 400 mAh to 450 mAh

Hardware Architecture and Circuit Solutions

At the core of the classic NanoVNA lies a superheterodyne architecture featuring a single switched receiver. The main functional units of the device are implemented using the following components:

1. Signal Synthesizer (Si5351A): The integrated dual-channel Si5351A clock generator chip produces the high-frequency signals for the reference Local Oscillator (LO) and the test stimulus. The signal from the Si5351 is a square wave, which inherently contains a large number of odd harmonics. At frequencies above 300 MHz, the NanoVNA utilizes the 3rd and 5th harmonics of the synthesizer to scan the RF range. This ingenious approach allowed expanding the measurement limit up to 900–1500 MHz without increasing the circuit cost.
2. Directional Coupler and Mixers: An RF bridge (Wheatstone bridge) extracts the reflected signal. The coupled signal is fed into AD8342 or classic SA602 mixers, which downconvert it to a low Intermediate Frequency (IF) of around 5–12 kHz.
3. Measurement Path and ADC (TLV320AIC3204): A high-quality, low-power stereo audio codec (TLV320AIC3204) serves as the Analog-to-Digital Converter (ADC) for the IF signals. It digitizes the low-frequency IF signals at a 48 kHz sampling rate, transmitting the data via the I2S bus directly to the controlling microcontroller.
4. Microcontroller (STM32F072C8T6 or GD32): This chip acts as the brain of the device. It performs overall device control, processes the digitized quadrature I/Q vectors, calculates the complex S-parameters, and renders the graphs onto the ILI9431 LCD screen. Since the signal processing is executed entirely in the digital domain, it ensures high parameter stability.

Lineup of device modifications: NanoVNA-H, NanoVNA-H4, and NanoVNA V2 SAA-2

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