Achieving wide frequency tuning range without sacrificing phase noise and power consumption with CMOS voltage controlled ring oscillators (VCRO) at scaled supply voltages is a big challenge. In this paper, we explore a double gate hetero-junction TFET (HTFET) based VCRO for the first time exploiting the steep subthreshold characteristics of TFETs at scaled supply voltages down to 150mV. It has been demonstrated that TFET based VCRO design achieves wide frequency tuning range for very low power consumption with satisfactory phase noise characteristics, making them suitable for wide frequency range on-chip clock generators/PLLs used in ultra-low power wireless sensor nodes for IoT.