Renesas GX36420-F-DNT

Overview

GX36420-F-DNT from Integrated Device Technology (IDT) is a quad-channel 64Gbps linear transimpedance amplifier (TIA) IC designed for coherent optical receiver front-ends in 400G/600G systems. It integrates four independent TIAs for XI/XQ/YI/YQ channels, supports 16QAM/64QAM modulation, delivers >40GHz 3dB bandwidth, 150–5000Ω differential gain, and >30dB dynamic range, and is optimized for CFP2/CFP4 optical modules.

For engineers reviewing the GX36420-F-DNT datasheet, GX36420-F-DNT pinout, GX36420-F-DNT application, or GX36420-F-DNT equivalent, key selection criteria include per-channel TIA bandwidth, gain adjustability, integrated SPI/analog control interface, DC offset cancellation capability, and compatibility with small-form-factor coherent module layouts.

Technical Context

The GX36420-F-DNT implements four fully independent linear TIA channels with dedicated VGA stages, DC offset loops, and peaking control per channel. Each channel features programmable gain control (AGC/MGC), peak detection, RSSI, input current monitoring, and shutdown functionality.

It integrates on-die ADC/DAC, SPI interface (CS/SCK/MOSI/MISO/RST), and analog bias controls for PD bias, output voltage, and gain configuration. The architecture supports simultaneous DC calibration across all four lanes while maintaining channel isolation and low crosstalk.

Key Specifications

Pinout & Package

Package: 120-pin flip-chip BGA (7.0 mm × 7.0 mm, 0.4 mm pitch), optimized for thermal performance and RF signal integrity in optical subassemblies.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad-channel high-speed linear TIA applications.

Compared with MAX3748AETE+T and LMH6401IRGTR, the GX36420-F-DNT uniquely delivers quad-channel 64Gbps linear amplification with on-die photodiode bias, SPI-configurable gain/offset/peaking, and coherent-specific monitoring functions-enabling direct integration into CFP2/CFP4 modules without discrete support components.

Availability

GX36420-F-DNT is available at Aetrix Electronics and suitable for 400G/600G coherent optical modules, CFP2/CFP4 pluggable transceivers, and lab-grade coherent receiver evaluation requiring stable component supply and long-term lifecycle assurance.

Supply support for GX36420-F-DNT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Integrated Device Technology (IDT), now part of Renesas Electronics, is a fabless semiconductor company specializing in timing, memory interface, RF, and high-speed signal conditioning solutions.

The GX36420-F-DNT belongs to IDT's coherent optical front-end product line, engineered specifically for next-generation 400G/600G transport systems using advanced modulation formats like 16QAM and 64QAM.

FAQ

What is the primary function of the GX36420-F-DNT in a coherent optical receiver?

The GX36420-F-DNT serves as a quad-channel linear transimpedance amplifier that converts weak photocurrents from four photodiodes (XI/XQ/YI/YQ) into clean, high-fidelity differential voltage signals. Its >40GHz bandwidth and >30dB dynamic range make it essential for preserving signal integrity in 64Gbps 16QAM/64QAM coherent detection. The GX36420-F-DNT integrates bias control, gain adjustment, and monitoring to replace multiple discrete components in CFP2/CFP4 modules.

Does the GX36420-F-DNT support automatic gain control (AGC) per channel?

Yes, the GX36420-F-DNT implements both automatic and manual gain control per channel via dedicated AGC loops and SPI-accessible registers. Each channel independently adjusts transimpedance gain in response to input signal level, RSSI feedback, or host command-critical for maintaining optimal ADC input swing across varying optical power. This functionality is built into the GX36420-F-DNT's analog core and requires no external circuitry.

What package type and thermal characteristics does the GX36420-F-DNT use?

The GX36420-F-DNT uses a 120-pin flip-chip BGA package measuring 7.0 mm × 7.0 mm with 0.4 mm pitch. Its flip-chip construction provides low thermal resistance and superior RF grounding-key for dissipating heat in compact CFP2/CFP4 modules. The device operates from –5°C to +85°C case temperature, and its thermal design supports continuous 64Gbps operation without derating when mounted on standard optical module PCBs.

Can the GX36420-F-DNT be used in non-coherent applications such as PAM4-based 400G-SR8?

No-the GX36420-F-DNT is optimized for linear operation in coherent receivers using 16QAM/64QAM modulation, with features like per-channel DC offset cancellation, peaking control, and RSSI tailored to complex-field signal recovery. It lacks the high-swing, decision-directed equalization needed for PAM4 NRZ/PAM4 direct detection. For 400G-SR8, purpose-built PAM4 TIAs like the ON Semiconductor NB7L14M are more appropriate than the GX36420-F-DNT.

How does the GX36420-F-DNT handle photodiode biasing?

The GX36420-F-DNT integrates four dedicated photodiode bias outputs (PD1–PD4), each driven by on-die DACs controlled via SPI. These outputs provide precise, programmable reverse-bias voltage for APD or PIN photodiodes-eliminating need for external bias ICs. Bias levels are calibrated per channel and can be adjusted dynamically to compensate for temperature drift or aging, a core capability of the GX36420-F-DNT's analog subsystem.