A Novel RF Power Detector Based on Positive and Negative Thermistors Using Standard CMOS Technology

Abstract

In this letter, a novel RF power detector (PD) that operates at X-band range is presented using standard 0.18- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> RF Complementary Metal Oxide Semiconductor (CMOS) technology. The proposed RF PD is mainly composed of a coplanar waveguide (CPW), two matched resistive loads and a Wheatstone full-bridge structure with positive and negative thermistors. Experimental results demonstrate that the device shows excellent RF-DC linearity, high sensitivity and stable impedance matching characteristics. In the power regions of [1, 200] mW, the measured sensitivities are <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$169.6~\mu \text{V}$ </tex-math></inline-formula> /mW, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$162.8~\mu \text{V}$ </tex-math></inline-formula> /mW, and 154.3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{V}$ </tex-math></inline-formula> /mW, at 8, 10, and 12 GHz, respectively. And the measured return loss is less than -19.1 dB at 8-12GHz. The total chip area is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${0.26}\times {0.4}$ </tex-math></inline-formula> mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , including all pads. Moreover, the absence of post-CMOS micromachining required for the RF PD fabrication with respect to a standard CMOS process would have a significant economic advantage as a low-cost PD with RF ICs.