Link-level performance of a monolithic InP microwave–photonic transceiver for LEO-distributed radar crosslinks

Satellite constellations in low Earth orbit (LEO) require inter-satellite communication (ISC) front-ends that meet strict size, weight, and power (SWaP) constraints. Conventional RF front-ends struggle to combine multi-GHz bandwidth, high linearity, and wideband tuning within these budgets. Microwave photonics offers a path forward by using optical components to generate, transport, and process RF signals. However, practical performance can be limited by optical-to-electrical interfaces, packaging, thermal parasitics, etc. This paper motivates a monolithic indium phosphide (InP) approach that reduces interconnect loss and minimizes assembly and coupling related performance variations. As a use-case scenario, we consider a distributed-radar system in which two satellites share waveform generation and reception over an inter-satellite link. We analyze the on-chip transceiver that enables this operation. This work studies a monolithic indium phosphide (InP) microwave–photonic transceiver that co-integrates the transmitter, receiver, and optical amplification on a single chip and quantifies its link-level performance. We perform circuit-level modeling to evaluate gain (G), noise figure (NF), and spurious-free dynamic range (SFDR) across representative C (4–8GHz), X (8–12GHz), and Ka (27–40GHz) bands using realistic device models. The modulator Vπ is swept from 2 to 8V. The results show that the preferred operating region is obtained for low Vπ, around 2 to 3V, and for photodiode input power just below saturation. In this region, the transmitter exhibits representative performance of G≈ +4.5dB, NF≈ 22.4dB, and SFDR≈ 110.8dB·Hz²/³, while the receiver exhibits G≈ −8dB, NF≈ 20dB, and SFDR≈ 111.2dB·Hz²/³. The results further indicate that the achievable tradeoff among G, NF, and SFDR is bounded by the photodiode linear operating region, and that these metrics must be considered jointly to guide design choices in the monolithic InP transceiver.