High-Voltage Programmable Attenuator Module

A digitally controlled high-voltage variable attenuator module featuring RC compensation, 1 Hz to 100 MHz bandwidth, and ±300V handling capability via an isolated SPI-driven relay/switch matrix.

Executive Summary

This reference design defines the system architecture, critical component candidates, risk register, and validation path for High-Voltage Variable Attenuator Module. It is a system-level design deliverable; verify critical claims with manufacturer evidence and prototype testing before production release.

Design Overview

Requirements Coverage

Requirement	Architecture coverage	Status
Digitally controlled variable attenuation with RC compensation	MCU	Covered
1 Hz to 100 MHz wide bandwidth operation	Pending validation	Needs verification
100 kΩ to 100 MΩ selectable resistance range	Pending validation	Needs verification
0.1 pF to 300 pF programmable capacitance range	Pending validation	Needs verification
±300V high-voltage handling with relay/switch matrix and SPI control	Pending validation	Needs verification

Item	Details
Product Type	High-Voltage Variable Attenuator Module
Key Functions	Digitally controlled variable attenuation with RC compensation, 1 Hz to 100 MHz wide bandwidth operation, 100 kΩ to 100 MΩ selectable resistance range, 0.1 pF to 300 pF programmable capacitance range, ±300V high-voltage handling with relay/switch matrix and SPI control
Power Source	AC 110-220V
Connectivity	SPI
Size	Compact embedded module / OEM PCB assembly
Environment	indoor
Difficulty	Advanced
Est. Time	5-8 hours

System Architecture

Power Topology: USB-C 5V → MCU 3.3V LDO

Module List

Module ID	Type	Name	Function	Voltage
POWER	POWER	USB-C Power Jack	Power input	5V
MCU	MCU	ESP32-WROOM-32	Main controller	3.3V

Power Tree and Signal Interfaces

From	To	Type	Interface / rail	Voltage
POWER	MCU	power	Power	-

Design Schemes

High-Voltage Variable Attenuator Module ★

Key IC selection

main controller and SPI master

• Need: Wi-Fi/BLE connectivity, rich GPIO, and hardware SPI to control HV switch matrices and receive attenuation commands
• Class: 32-bit Microcontroller with integrated Wi-Fi/Bluetooth and multiple SPI/UART peripherals
• Shortlist: Espressif ESP32-WROOM-32, Silicon Labs EFM32 + external module
• Pick: Select based on module availability, flash size (4MB/8MB), and FCC/CE modular certification status

USB-C power input and DC-DC regulation

• Need: Accept standard 5V USB-C power and generate stable low-voltage rails (3.3V) for the digital section plus isolated supplies for HV drivers
• Class: USB Type-C port protection/controller combined with synchronous step-down regulator and isolated DC-DC converters
• Shortlist: TI TPS62840 + Analog Devices isolated DC-DC, Richtek RT7252 + Murata isolated module
• Pick: Select based on quiescent current, low EMI performance, and galvanic isolation rating for ±300V safety barriers

Risk register

ID	Area	Severity	Detail	Mitigation
r1	emi	high	High voltage switching transients (±300V at up to 100 MHz signal paths) can couple noise into the ESP32 digital lines and USB-C interface.	Implement strict physical separation, optical or digital isolators on SPI lines controlling the HV switch matrix, and solid ground planes.
r2	supply	med	Creepage and clearance distances on the PCB for ±300V nodes may fail safety standards if standard low-voltage component spacing is used.	Enforce mandatory high-voltage PCB layout design rules, slot milling under isolation barriers, and proper coating/potting if necessary.

Bring-up and Validation Plan

1. Power-off inspection and rail resistance checks
2. Current-limited first power-up; verify every rail before enabling loads
3. Validate interfaces and timing one subsystem at a time
4. Run thermal, fault-injection, EMC pre-scan, and endurance tests for the target environment

Key Components

2/2 modules matched to real parts. See the BOM tab for the full component table.

USB-C Power Jack (USB4930-00-A)

The candidate MPN 'USB4930-00-A' matches the primary MPN and the manufacturer 'GCT' is acceptable since the preferred ma

ESP32-WROOM-32 (ESP32-WROOM-32)

The candidate MPN 'ESP32-WROOM-32' is an exact match for the primary MPN and the manufacturer matches Espressif Systems.

Build Summary

• Difficulty: Advanced
• Estimated time: 5-8 hours
• Tools required: Soldering Iron, Solder Wire, Flux, Digital Multimeter, Oscilloscope, Signal Generator

See the Build tab for the full step-by-step assembly guide.

Evidence and Limitations

• Confirm part parameters, certifications, and compatibility against current manufacturer documents.
• Treat industry compliance without test or certificate evidence as a compliance gap, not an approval.
• See Reference Images for visual artifacts and Build Guide for detailed assembly and bring-up steps.