## ADCMP564B: Ultra-Fast Voltage Comparator The **ADCMP564B** is a high-speed, dual-channel voltage comparator manufactured by Analog Devices. It is designed for applications requiring extremely low propagation delay and high precision in signal processing. ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Propagation Delay** | 700 ps (Typical) | | **Overdrive Dispersion** | 75 ps | | **Input Range** | -2.0 V to +3.0 V | | **Output Logic** | Differential PECL (Positive Emitter-Coupled Logic) | | **Supply Voltage** | +5.0 V (Vcc) and -5.2 V (Vee) | | **Package** | 20-lead LFCSP (Lead Frame Chip Scale Package) | --- ### 2. Functional Description The ADCMP564B is built on a high-speed silicon-germanium (SiGe) process. It consists of two independent comparators that convert analog input signals into differential PECL logic outputs. #### A. Input Stage The input stage is designed to handle a wide common-mode range. It features a high input impedance to minimize loading on the signal source. The device is particularly resilient against "overdrive dispersion," meaning the delay remains consistent even as the input signal strength changes. #### B. Latch Function The device includes a **latch-enable** input. - When the latch is open (transparent), the output tracks the input. - When the latch is closed, the output is held at its current state regardless of input changes. This is critical for high-speed data acquisition and sampling. #### C. Output Stage (PECL) The outputs are differential PECL. This logic type is preferred in high-frequency designs because: * It provides high noise immunity. * The differential nature minimizes electromagnetic interference (EMI). * It can drive 50 $\Omega$ transmission lines directly (usually terminated to $Vcc - 2V$). --- ### 3. Pin Configuration Overview | Pin Name | Description | | :--- | :--- | | **$V_{IN}+ / V_{IN}-$** | Differential Analog Inputs | | **$Q / \bar{Q}$** | Differential PECL Outputs | | **$LE / \bar{LE}$** | Latch Enable Inputs | | **$V_{CC}$** | Positive Supply (+5.0 V) | | **$V_{EE}$** | Negative Supply (-5.2 V) | --- ### 4. Common Applications * **Automatic Test Equipment (ATE):** High-speed timing and pin electronics. * **High-Speed Instrumentation:** Oscilloscopes and logic analyzers. * **Clock and Data Restoration:** Signal squaring and pulse sharpening. * **Threshold Detection:** Identifying fast-rising edges in nuclear or optical physics.