This　paper　presents　a　compact　Micro-Electro-Mechanical　System　(MEMS)　microphone　digital　readout　system.　The　system　is　characterized　by　a　low-dropout　regulator　(LDO)　and　a　pre-amplifier　and　programmable-gain　amplifier　(PPA)-less　voltage　controlled　oscillator　(VCO)-based　Delta　sigma　modulation　technique,　which　improve　compactness　and　design　scalability.　Specifically,　to　improve　signal　accuracy　and　maintain　loop　stability　without　a　gain-tuning　range　trade-off,　an　active　low　pass　filter　(ALPF)　and　a　current　mode　feed-forward　path　(CMFFP)　are　incorporated　in　a　VCO-based　delta-sigma　modulation　loop.　By　means　of　VCOs　and　SCG　phase　variation　robustness　and　current　source　array　feedback　(CSAFB),　the　system　achieves　a　high　power　supply　rejection　ratio　(PSRR)　and　gain　tuning　without　the　need　to　design　an　extra　regulator　and　PPA.　The　design　was　fabricated　using　a　180　nm　Bipolar-CMOS-DMOS　(BCD)　process　and　measured　at　a　1.2　V　supply　voltage.　According　to　the　measurement　results,　the　signal-to-noise　and　distortion　ratio　(SNDR)　achieves　62　dB@1　kHz　with　40　dB　gain　and　a　10　kHz　bandwidth.　Furthermore,　PSRR@1　kHz　is　below　-55　dB,　and　power　dissipation　is　within　57　mu　W.