We　propose　a　compact　InGaAsP/InP　electro-optic　ring　modulator　operated　with　coupling　modulation　that　can　circumvent　the　bandwidth　limitation　and　large　minimum　bend　radius　of　a　ring.　This　device　consists　of　frustrated　total　internal　reflection　(TIR)　couplers　and　TIR　mirrors　serving　as　90　degrees　waveguide　bends,　forming　the　configuration　of　an　asymmetric　rectangular　Mach-Zehnder　interferometer　coupled　to　a　square　ring　resonator　(SRR).　A　discrete-time　dynamic　model　and　finite-difference　time-domain　method　are　used　to　evaluate　the　device　performances,　and　the　theoretical　results　show　an　operating　frequency　up　to　60　GHz,　the　maximum　extinction　ratio　of　similar　to　12　dB,　the　low　electrical　energy　of　similar　to　60　fJ/bit,　and　a　compact　chip　size　of　similar　to　18　mu　m　x　29　mu　m,　respectively.　The　enabling　component　of　the　SRR　represents　＞　100-fold　footprint　reduction　on　a　chip.　This　compact　device　can　be　potentially　applied　in　large-scale　InP-based　photonic　integrated　circuits.