Precision Strain Gauge Amplifier PCB Design

Hi, I need help designing a precision strain gauge amplifier PCB for a pedal force sensor (PFS) project. Please read the requirements carefully. Project Overview Application: Pedal force measurement system Sensor: 350Ω full-bridge strain gauge Force range: 0 to 150 kg System requires both analog output and digital display (kg) Core Requirements 1. Analog Signal Conditioning Circuit Use INA333 (or equivalent modern low-noise instrumentation amplifier) Stable 5V bridge excitation using precision reference (e.g., REF5050 + buffer) Output range: Preferably 0–3.3V (acceptable: 0–5V) Gain designed for full-scale (150 kg) Include: Gain adjustment (trim or precision resistor) Offset/zero adjustment (via REF pin or equivalent) Proper low-pass filtering (~20–30 Hz) Output buffer (rail-to-rail op-amp like OPA333 or similar) 2. Parallel Digital Measurement (HX711) Same strain gauge signal must also feed: HX711 module (no pre-amplification before HX711) HX711 will be used with: TM1637 7-segment display module (to show weight in kg) Ensure: No signal interference between analog and HX711 paths Proper high-impedance connection and grounding strategy 3. PCB Design Requirements 2-layer PCB with solid ground plane Proper analog and digital ground separation (star grounding) Differential routing for strain gauge signals Noise minimization (very important — low-level mV signals) Compact and practical layout Suitable connectors for: Strain gauge (4-wire) Analog output HX711 interface 4. Deliverables Required Complete schematic (PDF + source file) PCB layout (Gerber + design files) BOM (components easily available in India preferred) Brief design notes: Gain calculation Calibration method (kg vs voltage) Important Notes This is a precision analog design, not a generic amplifier module Avoid using outdated ICs like AD620 unless justified Focus on: Low noise Stability Repeatability Goal To build a reliable, low-noise

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