## Overview of the PE35404 The **PE35404** is a high-performance, UltraCMOS® based **integer-N frequency synthesizer** designed by pSemi (formerly Peregrine Semiconductor). It is specifically engineered to operate in harsh environments, making it a staple in aerospace, defense, and high-reliability industrial applications. --- ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Frequency Range** | 100 MHz to 4.5 GHz | | **Technology** | UltraCMOS® on Sapphire | | **Phase Noise** | -216 dBc/Hz (Normalized Figure of Merit) | | **Supply Voltage** | 2.85V to 3.15V | | **Package** | 20-lead CQFP (Ceramic Quad Flatpack) | | **Rad-Hard Capability** | TID (Total Ionizing Dose) up to 100 krad (Si) | --- ### 2. Core Components and Architecture The internal circuitry of the PE35404 consists of several functional blocks that work together to provide stable frequency synthesis: 1. **Dual-Modulus Prescaler:** It utilizes a 5/6 or 10/11 prescaler to divide high-frequency input signals down to manageable levels for the counters. 2. **Phase-Frequency Detector (PFD):** Compares the reference frequency with the divided VCO frequency to generate an error signal. 3. **Programmable Counters:** Includes a 10-bit R-counter (reference) and a 16-bit M-counter (main feedback), allowing for high-resolution frequency selection. 4. **Serial Interface:** Uses a standard 3-wire CMOS interface for programming the internal registers and frequency settings. --- ### 3. Distinctive Advantages * **Radiation Tolerance:** Unlike standard CMOS parts, the UltraCMOS technology on a sapphire substrate makes the PE35404 immune to **Single-Event Latch-up (SEL)**, which is critical for satellite and space station hardware. * **Low Power Consumption:** Optimized for systems where thermal management and battery life are constraints. * **High Isolation:** The sapphire substrate provides excellent electrical isolation between internal components, resulting in superior signal integrity. --- ### 4. Typical Application Circuit When integrating the PE35404, the typical signal chain involves: 1. **TCXO/Ref Clock:** Feeds the reference input. 2. **External VCO:** The PE35404 controls an external Voltage Controlled Oscillator. 3. **Loop Filter:** A passive RC network that sits between the PE35404 charge pump output and the VCO tuning input. ```c // Example Pseudocode for Register Programming (SPI-like) void programPE35404(uint32_t r_count, uint32_t m_count) { send_to_synth(R_REGISTER, r_count); // Set reference divider send_to_synth(M_REGISTER, m_count); // Set main feedback divider apply_le_pulse(); // Latch Enable to update frequency } ```